Towards synthesis of a minimal cell
- Thread starter ThaG
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That is why you never assume to quick. You didn't even check it out.
So the Words "I believe" have nothing to do with science? Wow, if this statement doesn't relieve you of all your credentials in here, I don't know what to say anymore. *SMH* like I did in class yesterday, when an atheist said, the Bible was the Rosetta Stone.
So the Words "I believe" have nothing to do with science? Wow, if this statement doesn't relieve you of all your credentials in here, I don't know what to say anymore. *SMH* like I did in class yesterday, when an atheist said, the Bible was the Rosetta Stone.
You don't like the jargon - I can't help you
Imagine you've spent all your life studying something and you've achieved some good level of understanding of the matter and somebody who doesn't know shit about it comes and starts telling you're wrong and your knowledge doesn't mean anything....
How will you react?
Imagine you've spent all your life studying something and you've achieved some good level of understanding of the matter and somebody who doesn't know shit about it comes and starts telling you're wrong and your knowledge doesn't mean anything....
How will you react?
The evidence is consciousness, which is apparently superior to the bodily senses. For example, by consciousness you are aware of the hearing, seeing, touching, smelling and tasting capacities, but these bodily senses cannot experience consciousness. This is scientific and can be observed by anyone. And since consciousness is superior to the bodily senses, to presume that it has a material origin is, well, preposterous. The common mistake people make is that we are ever in direct contact with another's consciousness. Based on this presumption, it is perceived that when bodily death occurs, that means the conscious entity is extinguished from existence. But we only know our own consciousness. What we perceive in others is simply the symptoms of consciousness in a body. So when we no longer see these symptoms in a body, it does not logically mean that the conscious soul or self is no longer existing. And given the seemingly constant nature of the self in contrast to an ever-changing body, it tends to make more sense that the self persists even in the circumstance of bodily death.
I haven't seen it demonstrated as a fact. Evolution theory is one of those things that dwells in the realm of potential tangible evidence. It doesn't deal with the subtle sciences of self, for example. Evolution may fit some observations, but other ones it does not. These 'other ones' tend to get less emphasis put on them or they get practically swept under the rug because this evolution theory is more prominent and popular nowadays. I've mentioned this book before, but you dismissed it - that is, Forbidden Archeology. I recommend you read it, because I don't think you have. Whether or not you agree with the replacing theory the author puts forward in a completely separate book, I think Forbidden Archeology shows numerous examples of how biases happen even in the name of science. And it really isn't some secret illuminati plot, but rather just a flaw in human nature. In my opinion (which may not be worth much) Forbidden Archeology gives the most reasonable and unbiased look at the totality of archeological and anthropological evidence. It doesn't disprove evolution theory altogether, though it does show evidence that contradicts the current evolutionary timeline, specifically concerning man's origins. One could easily postulate that man must have evolved even earlier than currently thought.
I am referring to how the human species is closer to divinity than, say, an ostrich in how the former has higher brain functions than the latter. I am not rejecting the ostrich from being factually a transcendental soul as the human is, but I am observing that the intelligence capacity of a human body is greater than that of an ostrich body. The common theme you will find in my logic is that we are dealing with two entities: the self and the body. A 60 watt light bulb is a 60 watt light bulb. You put it in a small closet and it fills that capacity. You install it in a dining room and it fills that somewhat larger capacity. In both cases it is just a 60 watt light bulb. Similarly, a soul is a soul; living entity is a living entity. Different bodies, different capacities. A bird does not have a "flying" soul, and a dog does not have a "barking" one. These are qualities that pertain only to the body. It is therefore important to discern between the self and the body.
Whatever you call it, I just see a theory made from an interpretation of some evidence. I don't see hard facts. You may feel that it is a reasonable theory to accept, but I don't feel that way. I like to get right to the root assumptions that drive any theory or field of knowledge, and if I notice that those root assumptions are not ones that I am willing to subscribe to, I am very cautious toward that particular theory. In this case, as in most cases, the root assumption is that self is produced at some mature stage of material/chemical process. Based on this conception, all life boils down to a physical process with survival as the end all, be all of existence. This gives way to mutation through natural selection and whatnot. Since I don't accept the premise, I am naturally reluctant to accept the conclusion.
In my understanding, evolution occurs in the sense that the soul has the potential (or lack thereof) of transmigrating from one body to another. This changing of bodies is going on even without considering the death of one. Because within a so-called single lifespan, the body changes vastly. One has a baby body, then a child body, then a youth body, then an adult body, then an old body. So based on this observation as well as the one that suggests the self as being comparatively transcendental in nature; just as one changes body from youth to old age, one makes a similar change at the time of death. The idea that one species eventually transforms or splits off into another species is a theory that lacks knowledge of the self. It doesn't take that into account at all. I can rent a small apartment, and then if I meet the qualifications, I can rent a larger house. It is not that my apartment evolves into a house. There is the apartment and there is the house, existing simultaneously. Similarly, there are all these types of bodies existing simultaneously for vacancy. I completely understand the tendency to look for a singular origin, but I am a firm believer that such a singularity needn't necessarily undermine the variegatedness of living organisms. What these naturalist/materialists are proposing is a singular origin concerning the material bodies, but if they had knowledge of the transcendental self, another, greater singularity would be understood and there would be no need to postulate one in terms of the aggregate of physical species.
Perhaps you can explicate on this comparative genomics, but be aware that I don't subscribe to the same basic premise about life and existence as you do. So if your intention is to convert me into your understanding, then it may be a waste of your time. On the other hand, if you just want to share ideas, then I think that could have good potential.
No. I didn't. I referred to some people who don't see a contradiction in the theory of evolution and the idea that a supreme being is overall responsible. My rejection of a species-to-species evolution is based on a more in depth understanding of the self, and my understanding of a supreme being follows in the same line of reaoning, which, including my personal faith in religious texts, gives the overall package an overwhelmingly contradictory picture than the one painted by the naturalists (one who follows the philosophy of naturalism) and non-theists.
Why do you think that? You only spoke about synthesizing a minimal cell and then later synthesizing a human zygote. Where does the evolution part take place? It may be in there somewhere, but you're going to need to perhaps go into more details.
I haven't seen it demonstrated as a fact. Evolution theory is one of those things that dwells in the realm of potential tangible evidence. It doesn't deal with the subtle sciences of self, for example. Evolution may fit some observations, but other ones it does not. These 'other ones' tend to get less emphasis put on them or they get practically swept under the rug because this evolution theory is more prominent and popular nowadays. I've mentioned this book before, but you dismissed it - that is, Forbidden Archeology. I recommend you read it, because I don't think you have. Whether or not you agree with the replacing theory the author puts forward in a completely separate book, I think Forbidden Archeology shows numerous examples of how biases happen even in the name of science. And it really isn't some secret illuminati plot, but rather just a flaw in human nature. In my opinion (which may not be worth much) Forbidden Archeology gives the most reasonable and unbiased look at the totality of archeological and anthropological evidence. It doesn't disprove evolution theory altogether, though it does show evidence that contradicts the current evolutionary timeline, specifically concerning man's origins. One could easily postulate that man must have evolved even earlier than currently thought.
I am referring to how the human species is closer to divinity than, say, an ostrich in how the former has higher brain functions than the latter. I am not rejecting the ostrich from being factually a transcendental soul as the human is, but I am observing that the intelligence capacity of a human body is greater than that of an ostrich body. The common theme you will find in my logic is that we are dealing with two entities: the self and the body. A 60 watt light bulb is a 60 watt light bulb. You put it in a small closet and it fills that capacity. You install it in a dining room and it fills that somewhat larger capacity. In both cases it is just a 60 watt light bulb. Similarly, a soul is a soul; living entity is a living entity. Different bodies, different capacities. A bird does not have a "flying" soul, and a dog does not have a "barking" one. These are qualities that pertain only to the body. It is therefore important to discern between the self and the body.
Whatever you call it, I just see a theory made from an interpretation of some evidence. I don't see hard facts. You may feel that it is a reasonable theory to accept, but I don't feel that way. I like to get right to the root assumptions that drive any theory or field of knowledge, and if I notice that those root assumptions are not ones that I am willing to subscribe to, I am very cautious toward that particular theory. In this case, as in most cases, the root assumption is that self is produced at some mature stage of material/chemical process. Based on this conception, all life boils down to a physical process with survival as the end all, be all of existence. This gives way to mutation through natural selection and whatnot. Since I don't accept the premise, I am naturally reluctant to accept the conclusion.
In my understanding, evolution occurs in the sense that the soul has the potential (or lack thereof) of transmigrating from one body to another. This changing of bodies is going on even without considering the death of one. Because within a so-called single lifespan, the body changes vastly. One has a baby body, then a child body, then a youth body, then an adult body, then an old body. So based on this observation as well as the one that suggests the self as being comparatively transcendental in nature; just as one changes body from youth to old age, one makes a similar change at the time of death. The idea that one species eventually transforms or splits off into another species is a theory that lacks knowledge of the self. It doesn't take that into account at all. I can rent a small apartment, and then if I meet the qualifications, I can rent a larger house. It is not that my apartment evolves into a house. There is the apartment and there is the house, existing simultaneously. Similarly, there are all these types of bodies existing simultaneously for vacancy. I completely understand the tendency to look for a singular origin, but I am a firm believer that such a singularity needn't necessarily undermine the variegatedness of living organisms. What these naturalist/materialists are proposing is a singular origin concerning the material bodies, but if they had knowledge of the transcendental self, another, greater singularity would be understood and there would be no need to postulate one in terms of the aggregate of physical species.
Perhaps you can explicate on this comparative genomics, but be aware that I don't subscribe to the same basic premise about life and existence as you do. So if your intention is to convert me into your understanding, then it may be a waste of your time. On the other hand, if you just want to share ideas, then I think that could have good potential.
No. I didn't. I referred to some people who don't see a contradiction in the theory of evolution and the idea that a supreme being is overall responsible. My rejection of a species-to-species evolution is based on a more in depth understanding of the self, and my understanding of a supreme being follows in the same line of reaoning, which, including my personal faith in religious texts, gives the overall package an overwhelmingly contradictory picture than the one painted by the naturalists (one who follows the philosophy of naturalism) and non-theists.
Why do you think that? You only spoke about synthesizing a minimal cell and then later synthesizing a human zygote. Where does the evolution part take place? It may be in there somewhere, but you're going to need to perhaps go into more details.
So you think consciousness can't be material based and must be something transcedental? How do you explain the fact that mutations cause severe mental retardation? How do you explain the fact that certain drugs can drastically alter human behaviour, in fact, how do you explain the action of opiats in general? I can explain these things in terms of molecules and pathways that they attack.
It seems that you're not aware that we're begining to understand in great molecular detail the mechanisms of memory, neural and synapitc plasticity and behaviour and there is nothing but molecules there. If you want a detailed description of what's known,I can provide it.
There is absolutely no reason to seek explanation of human beyond molecules, pathways and cells other than certain santimental reasons concerning the place of Homo sapiens among the other species
If you haven't seen it demonstrated as a fact, you have serious hole in your education which I suggest that you fill ASAP.
Anybody can write a book like Forbidden Archaeology and claim it's real science. The key word is publications in peer-reviwed journals.
BTW don't forget that the biggest dream of any scientist is to prove an established theory wrong - this the stuff that makes you great and guarantees that your name will be in the textbooks. So if evolution theory was wrong, it would have been shown to be wrong long ago, especially given the fact that it's so emotionally charged. But it's not, not only that, but it hasn't even been argued against in the last 100 years. Don't forget that those who created and established the theory had the same kind of problem you have with it - it changed their whole worldview in a very uncomfortable way, yet they insisted on the scientific truth instead on their religous beliefs.
I don't know what to tell you, your whole thinking is so unscientific and filled with false concepts, which you seem to blindly believe in, that it will be very hard to argue with it.
First, you say that humans are closer to God and then base your arguments on things like soul, well, you have no proof of the existence of any of these things. I can tell you that everyone of us is just a robot ruled by his personal little tea cup flying somewhere between Pluto and Neptun and you can't disprove it at all so it might be true (I let you estimate the possiblity), but it's actually the same type of argument as the ones you present
LMAO
So if you don't like the theory, it's wrong?????
Are you crazy? You don't have enough evidence? What evidence do you have supporting your "hypothese" which is plain ridiculous BTW?
I will tell you why you don't like the theory: because somebody (you) was too lazy to get his ass off and read some books about evolution, check the facts, think about them critically and see whether they match the observations or not and only then talk bullshit and make a fool of himself
"If I don't like the theory, I won't believe in it", wow
Science doesn't care about what you think, it cares about what's true
Have you ever heard about Okham's razor and the least parsimonious explanation?
See, the religious texts and your personal beliefs don't mean shit
What's important is the world around us, you must be a fool to ignore it. Your rejection of species-to-species evolution is based on religious dogmatism, pure ignorance and low intellect.
BTW species-to-species evolution has been observed in modern times, there are numerous examples.
It seems that you're not aware that we're begining to understand in great molecular detail the mechanisms of memory, neural and synapitc plasticity and behaviour and there is nothing but molecules there. If you want a detailed description of what's known,I can provide it.
There is absolutely no reason to seek explanation of human beyond molecules, pathways and cells other than certain santimental reasons concerning the place of Homo sapiens among the other species
If you haven't seen it demonstrated as a fact, you have serious hole in your education which I suggest that you fill ASAP.
Anybody can write a book like Forbidden Archaeology and claim it's real science. The key word is publications in peer-reviwed journals.
BTW don't forget that the biggest dream of any scientist is to prove an established theory wrong - this the stuff that makes you great and guarantees that your name will be in the textbooks. So if evolution theory was wrong, it would have been shown to be wrong long ago, especially given the fact that it's so emotionally charged. But it's not, not only that, but it hasn't even been argued against in the last 100 years. Don't forget that those who created and established the theory had the same kind of problem you have with it - it changed their whole worldview in a very uncomfortable way, yet they insisted on the scientific truth instead on their religous beliefs.
I don't know what to tell you, your whole thinking is so unscientific and filled with false concepts, which you seem to blindly believe in, that it will be very hard to argue with it.
First, you say that humans are closer to God and then base your arguments on things like soul, well, you have no proof of the existence of any of these things. I can tell you that everyone of us is just a robot ruled by his personal little tea cup flying somewhere between Pluto and Neptun and you can't disprove it at all so it might be true (I let you estimate the possiblity), but it's actually the same type of argument as the ones you present
LMAO
So if you don't like the theory, it's wrong?????
Are you crazy? You don't have enough evidence? What evidence do you have supporting your "hypothese" which is plain ridiculous BTW?
I will tell you why you don't like the theory: because somebody (you) was too lazy to get his ass off and read some books about evolution, check the facts, think about them critically and see whether they match the observations or not and only then talk bullshit and make a fool of himself
"If I don't like the theory, I won't believe in it", wow
Science doesn't care about what you think, it cares about what's true
Have you ever heard about Okham's razor and the least parsimonious explanation?
See, the religious texts and your personal beliefs don't mean shit
What's important is the world around us, you must be a fool to ignore it. Your rejection of species-to-species evolution is based on religious dogmatism, pure ignorance and low intellect.
BTW species-to-species evolution has been observed in modern times, there are numerous examples.
Refer back to my light bulb analogy. The light fills the capacity of the room it fills. Similarly, consciousness - the symptom of the soul - fills the capacity of the body. If damage is done to the brain or some type of mutation, that will affect consciousness within a body.
You are not actually seeing cause, but only effect.
Your sentiment is that lifeless matter moves and interacts with itself until life just happens to be produced. My sentiment is that matter only moves and interacts with itself because a living entity exists.
Baseless conjecture.
All the book is doing is reviewing scientific evidence. It is not manufacturing it's own evidence. The author didn't go out digging for evidence. So stop making excuses.
Yet the current timeline of evolution has been shown incorrect if we look at all the compiled evidence. Once again, I can only refer you to that book. It is what it is. The scientific truth is not what you assert.
No. It is simply not a science that you identify with because you base your understanding on a different premise, namely that life is produced from matter.
Bad analogy. The concept of the self/soul as a transcendental entity is based on observation. We know that one's self exists. That is a given. So the next step is to analyze the nature of the self. Consider it's capacity to persist and to be master of the senses, and then consider the fleeting nature of material objects the senses come in contact with. This is the science. The flying tea cup is not based on any observations, nor can it even be approached through inductive reasoning. It is simply a poor attempt at mock religion like the invisible pink unicorn or flying spaghetti monster.
*hands ass back to you*
That's not what I said. I said if I do not subscribe to the basic premise. The premise is something that is accepted by default. If I don't accept it by default, then the house of cards comes tumbling down.
I have presented that evidence already: consciousness. Such evidence takes precedence over data gathered and analyzed subject to bodily senses that are themselves inferior to consciousness.
You haven't been listening.
Wow is right. You just made up a quote and responded to it.
Science isn't a person. Science doesn't care about anything.
Yes.
Your devout acceptance of species-to-species evolution is based on religious dogmatism. There are actually reasons why evolution remains a theory.
Name one.
You are not actually seeing cause, but only effect.
Your sentiment is that lifeless matter moves and interacts with itself until life just happens to be produced. My sentiment is that matter only moves and interacts with itself because a living entity exists.
Baseless conjecture.
All the book is doing is reviewing scientific evidence. It is not manufacturing it's own evidence. The author didn't go out digging for evidence. So stop making excuses.
Yet the current timeline of evolution has been shown incorrect if we look at all the compiled evidence. Once again, I can only refer you to that book. It is what it is. The scientific truth is not what you assert.
No. It is simply not a science that you identify with because you base your understanding on a different premise, namely that life is produced from matter.
Bad analogy. The concept of the self/soul as a transcendental entity is based on observation. We know that one's self exists. That is a given. So the next step is to analyze the nature of the self. Consider it's capacity to persist and to be master of the senses, and then consider the fleeting nature of material objects the senses come in contact with. This is the science. The flying tea cup is not based on any observations, nor can it even be approached through inductive reasoning. It is simply a poor attempt at mock religion like the invisible pink unicorn or flying spaghetti monster.
*hands ass back to you*
That's not what I said. I said if I do not subscribe to the basic premise. The premise is something that is accepted by default. If I don't accept it by default, then the house of cards comes tumbling down.
I have presented that evidence already: consciousness. Such evidence takes precedence over data gathered and analyzed subject to bodily senses that are themselves inferior to consciousness.
You haven't been listening.
Wow is right. You just made up a quote and responded to it.
Science isn't a person. Science doesn't care about anything.
Yes.
Your devout acceptance of species-to-species evolution is based on religious dogmatism. There are actually reasons why evolution remains a theory.
Name one.
5.0 Observed Instances of Speciation
The following are several examples of observations of speciation.
5.1 Speciations Involving Polyploidy, Hybridization or Hybridization Followed by Polyploidization.
5.1.1 Plants
(See also the discussion in de Wet 1971).
5.1.1.1 Evening Primrose (Oenothera gigas)
While studying the genetics of the evening primrose, Oenothera lamarckiana, de Vries (1905) found an unusual variant among his plants. O. lamarckiana has a chromosome number of 2N = 14. The variant had a chromosome number of 2N = 28. He found that he was unable to breed this variant with O. lamarckiana. He named this new species O. gigas.
5.1.1.2 Kew Primrose (Primula kewensis)
Digby (1912) crossed the primrose species Primula verticillata and P. floribunda to produce a sterile hybrid. Polyploidization occurred in a few of these plants to produce fertile offspring. The new species was named P. kewensis. Newton and Pellew (1929) note that spontaneous hybrids of P. verticillata and P. floribunda set tetraploid seed on at least three occasions. These happened in 1905, 1923 and 1926.
5.1.1.3 Tragopogon
Owenby (1950) demonstrated that two species in this genus were produced by polyploidization from hybrids. He showed that Tragopogon miscellus found in a colony in Moscow, Idaho was produced by hybridization of T. dubius and T. pratensis. He also showed that T. mirus found in a colony near Pullman, Washington was produced by hybridization of T. dubius and T. porrifolius. Evidence from chloroplast DNA suggests that T. mirus has originated independently by hybridization in eastern Washington and western Idaho at least three times (Soltis and Soltis 1989). The same study also shows multiple origins for T. micellus.
5.1.1.4 Raphanobrassica
The Russian cytologist Karpchenko (1927, 1928) crossed the radish, Raphanus sativus, with the cabbage, Brassica oleracea. Despite the fact that the plants were in different genera, he got a sterile hybrid. Some unreduced gametes were formed in the hybrids. This allowed for the production of seed. Plants grown from the seeds were interfertile with each other. They were not interfertile with either parental species. Unfortunately the new plant (genus Raphanobrassica) had the foliage of a radish and the root of a cabbage.
5.1.1.5 Hemp Nettle (Galeopsis tetrahit)
A species of hemp nettle, Galeopsis tetrahit, was hypothesized to be the result of a natural hybridization of two other species, G. pubescens and G. speciosa (Muntzing 1932). The two species were crossed. The hybrids matched G. tetrahit in both visible features and chromosome morphology.
5.1.1.6 Madia citrigracilis
Along similar lines, Clausen et al. (1945) hypothesized that Madia citrigracilis was a hexaploid hybrid of M. gracilis and M. citriodora As evidence they noted that the species have gametic chromosome numbers of n = 24, 16 and 8 respectively. Crossing M. gracilis and M. citriodora resulted in a highly sterile triploid with n = 24. The chromosomes formed almost no bivalents during meiosis. Artificially doubling the chromosome number using colchecine produced a hexaploid hybrid which closely resembled M. citrigracilis and was fertile.
5.1.1.7 Brassica
Frandsen (1943, 1947) was able to do this same sort of recreation of species in the genus Brassica (cabbage, etc.). His experiments showed that B. carinata (n = 17) may be recreated by hybridizing B. nigra (n = 8) and B. oleracea, B. juncea (n = 18) may be recreated by hybridizing B. nigra and B. campestris (n = 10), and B. napus (n = 19) may be recreated by hybridizing B. oleracea and B. campestris.
5.1.1.8 Maidenhair Fern (Adiantum pedatum)
Rabe and Haufler (1992) found a naturally occurring diploid sporophyte of maidenhair fern which produced unreduced (2N) spores. These spores resulted from a failure of the paired chromosomes to dissociate during the first division of meiosis. The spores germinated normally and grew into diploid gametophytes. These did not appear to produce antheridia. Nonetheless, a subsequent generation of tetraploid sporophytes was produced. When grown in the lab, the tetraploid sporophytes appear to be less vigorous than the normal diploid sporophytes. The 4N individuals were found near Baldwin City, Kansas.
5.1.1.9 Woodsia Fern (Woodsia abbeae)
Woodsia abbeae was described as a hybrid of W. cathcariana and W. ilvensis (Butters 1941). Plants of this hybrid normally produce abortive sporangia containing inviable spores. In 1944 Butters found a W. abbeae plant near Grand Portage, Minn. that had one fertile frond (Butters and Tryon 1948). The apical portion of this frond had fertile sporangia. Spores from this frond germinated and grew into prothallia. About six months after germination sporophytes were produced. They survived for about one year. Based on cytological evidence, Butters and Tryon concluded that the frond that produced the viable spores had gone tetraploid. They made no statement as to whether the sporophytes grown produced viable spores.
5.1.2 Animals
Speciation through hybridization and/or polyploidy has long been considered much less important in animals than in plants [[[refs.]]]. A number of reviews suggest that this view may be mistaken. (Lokki and Saura 1980; Bullini and Nascetti 1990; Vrijenhoek 1994). Bullini and Nasceti (1990) review chromosomal and genetic evidence that suggest that speciation through hybridization may occur in a number of insect species, including walking sticks, grasshoppers, blackflies and cucurlionid beetles. Lokki and Saura (1980) discuss the role of polyploidy in insect evolution. Vrijenhoek (1994) reviews the literature on parthenogenesis and hybridogenesis in fish. I will tackle this topic in greater depth in the next version of this document.
5.2 Speciations in Plant Species not Involving Hybridization or Polyploidy
5.2.1 Stephanomeira malheurensis
Gottlieb (1973) documented the speciation of Stephanomeira malheurensis. He found a single small population (< 250 plants) among a much larger population (> 25,000 plants) of S. exigua in Harney Co., Oregon. Both species are diploid and have the same number of chromosomes (N = 8). S. exigua is an obligate outcrosser exhibiting sporophytic self-incompatibility. S. malheurensis exhibits no self-incompatibility and self-pollinates. Though the two species look very similar, Gottlieb was able to document morphological differences in five characters plus chromosomal differences. F1 hybrids between the species produces only 50% of the seeds and 24% of the pollen that conspecific crosses produced. F2 hybrids showed various developmental abnormalities.
5.2.2 Maize (Zea mays)
Pasterniani (1969) produced almost complete reproductive isolation between two varieties of maize. The varieties were distinguishable by seed color, white versus yellow. Other genetic markers allowed him to identify hybrids. The two varieties were planted in a common field. Any plant's nearest neighbors were always plants of the other strain. Selection was applied against hybridization by using only those ears of corn that showed a low degree of hybridization as the source of the next years seed. Only parental type kernels from these ears were planted. The strength of selection was increased each year. In the first year, only ears with less than 30% intercrossed seed were used. In the fifth year, only ears with less than 1% intercrossed seed were used. After five years the average percentage of intercrossed matings dropped from 35.8% to 4.9% in the white strain and from 46.7% to 3.4% in the yellow strain.
5.2.3 Speciation as a Result of Selection for Tolerance to a Toxin: Yellow Monkey Flower (Mimulus guttatus)
At reasonably low concentrations, copper is toxic to many plant species. Several plants have been seen to develop a tolerance to this metal (Macnair 1981). Macnair and Christie (1983) used this to examine the genetic basis of a postmating isolating mechanism in yellow monkey flower. When they crossed plants from the copper tolerant "Copperopolis" population with plants from the nontolerant "Cerig" population, they found that many of the hybrids were inviable. During early growth, just after the four leaf stage, the leaves of many of the hybrids turned yellow and became necrotic. Death followed this. This was seen only in hybrids between the two populations. Through mapping studies, the authors were able to show that the copper tolerance gene and the gene responsible for hybrid inviability were either the same gene or were very tightly linked. These results suggest that reproductive isolation may require changes in only a small number of genes.
5.3 The Fruit Fly Literature
5.3.1 Drosophila paulistorum
Dobzhansky and Pavlovsky (1971) reported a speciation event that occurred in a laboratory culture of Drosophila paulistorum sometime between 1958 and 1963. The culture was descended from a single inseminated female that was captured in the Llanos of Colombia. In 1958 this strain produced fertile hybrids when crossed with conspecifics of different strains from Orinocan. From 1963 onward crosses with Orinocan strains produced only sterile males. Initially no assortative mating or behavioral isolation was seen between the Llanos strain and the Orinocan strains. Later on Dobzhansky produced assortative mating (Dobzhansky 1972).
5.3.2 Disruptive Selection on Drosophila melanogaster
Thoday and Gibson (1962) established a population of Drosophila melanogaster from four gravid females. They applied selection on this population for flies with the highest and lowest numbers of sternoplural chaetae (hairs). In each generation, eight flies with high numbers of chaetae were allowed to interbreed and eight flies with low numbers of chaetae were allowed to interbreed. Periodically they performed mate choice experiments on the two lines. They found that they had produced a high degree of positive assortative mating between the two groups. In the decade or so following this, eighteen labs attempted unsuccessfully to reproduce these results. References are given in Thoday and Gibson 1970.
5.3.3 Selection on Courtship Behavior in Drosophila melanogaster
Crossley (1974) was able to produce changes in mating behavior in two mutant strains of D. melanogaster. Four treatments were used. In each treatment, 55 virgin males and 55 virgin females of both ebony body mutant flies and vestigial wing mutant flies (220 flies total) were put into a jar and allowed to mate for 20 hours. The females were collected and each was put into a separate vial. The phenotypes of the offspring were recorded. Wild type offspring were hybrids between the mutants. In two of the four treatments, mating was carried out in the light. In one of these treatments all hybrid offspring were destroyed. This was repeated for 40 generations. Mating was carried out in the dark in the other two treatments. Again, in one of these all hybrids were destroyed. This was repeated for 49 generations. Crossley ran mate choice tests and observed mating behavior. Positive assortative mating was found in the treatment which had mated in the light and had been subject to strong selection against hybridization. The basis of this was changes in the courtship behaviors of both sexes. Similar experiments, without observation of mating behavior, were performed by Knight, et al. (1956).
5.3.4 Sexual Isolation as a Byproduct of Adaptation to Environmental Conditions in Drosophila melanogaster
Kilias, et al. (1980) exposed D. melanogaster populations to different temperature and humidity regimes for several years. They performed mating tests to check for reproductive isolation. They found some sterility in crosses among populations raised under different conditions. They also showed some positive assortative mating. These things were not observed in populations which were separated but raised under the same conditions. They concluded that sexual isolation was produced as a byproduct of selection.
5.3.5 Sympatric Speciation in Drosophila melanogaster
In a series of papers (Rice 1985, Rice and Salt 1988 and Rice and Salt 1990) Rice and Salt presented experimental evidence for the possibility of sympatric speciation. They started from the premise that whenever organisms sort themselves into the environment first and then mate locally, individuals with the same habitat preferences will necessarily mate assortatively. They established a stock population of D. melanogaster with flies collected in an orchard near Davis, California. Pupae from the culture were placed into a habitat maze. Newly emerged flies had to negotiate the maze to find food. The maze simulated several environmental gradients simultaneously. The flies had to make three choices of which way to go. The first was between light and dark (phototaxis). The second was between up and down (geotaxis). The last was between the scent of acetaldehyde and the scent of ethanol (chemotaxis). This divided the flies among eight habitats. The flies were further divided by the time of day of emergence. In total the flies were divided among 24 spatio-temporal habitats.
They next cultured two strains of flies that had chosen opposite habitats. One strain emerged early, flew upward and was attracted to dark and acetaldehyde. The other emerged late, flew downward and was attracted to light and ethanol. Pupae from these two strains were placed together in the maze. They were allowed to mate at the food site and were collected. Eye color differences between the strains allowed Rice and Salt to distinguish between the two strains. A selective penalty was imposed on flies that switched habitats. Females that switched habitats were destroyed. None of their gametes passed into the next generation. Males that switched habitats received no penalty. After 25 generations of this mating tests showed reproductive isolation between the two strains. Habitat specialization was also produced.
They next repeated the experiment without the penalty against habitat switching. The result was the same -- reproductive isolation was produced. They argued that a switching penalty is not necessary to produce reproductive isolation. Their results, they stated, show the possibility of sympatric speciation.
5.3.6 Isolation Produced as an Incidental Effect of Selection on several Drosophila species
In a series of experiments, del Solar (1966) derived positively and negatively geotactic and phototactic strains of D. pseudoobscura from the same population by running the flies through mazes. Flies from different strains were then introduced into mating chambers (10 males and 10 females from each strain). Matings were recorded. Statistically significant positive assortative mating was found.
In a separate series of experiments Dodd (1989) raised eight populations derived from a single population of D. Pseudoobscura on stressful media. Four populations were raised on a starch based medium, the other four were raised on a maltose based medium. The fly populations in both treatments took several months to get established, implying that they were under strong selection. Dodd found some evidence of genetic divergence between flies in the two treatments. He performed mate choice tests among experimental populations. He found statistically significant assortative mating between populations raised on different media, but no assortative mating among populations raised within the same medium regime. He argued that since there was no direct selection for reproductive isolation, the behavioral isolation results from a pleiotropic by-product to adaptation to the two media. Schluter and Nagel (1995) have argued that these results provide experimental support for the hypothesis of parallel speciation.
Less dramatic results were obtained by growing D. willistoni on media of different pH levels (de Oliveira and Cordeiro 1980). Mate choice tests after 26, 32, 52 and 69 generations of growth showed statistically significant assortative mating between some populations grown in different pH treatments. This ethological isolation did not always persist over time. They also found that some crosses made after 106 and 122 generations showed significant hybrid inferiority, but only when grown in acid medium.
5.3.7 Selection for Reinforcement in Drosophila melanogaster
Some proposed models of speciation rely on a process called reinforcement to complete the speciation process. Reinforcement occurs when to partially isolated allopatric populations come into contact. Lower relative fitness of hybrids between the two populations results in increased selection for isolating mechanisms. I should note that a recent review (Rice and Hostert 1993) argues that there is little experimental evidence to support reinforcement models. Two experiments in which the authors argue that their results provide support are discussed below.
Ehrman (1971) established strains of wild-type and mutant (black body) D. melanogaster. These flies were derived from compound autosome strains such that heterotypic matings would produce no progeny. The two strains were reared together in common fly cages. After two years, the isolation index generated from mate choice experiments had increased from 0.04 to 0.43, indicating the appearance of considerable assortative mating. After four years this index had risen to 0.64 (Ehrman 1973).
Along the same lines, Koopman (1950) was able to increase the degree of reproductive isolation between two partially isolated species, D. pseudoobscura and D. persimilis.
5.3.8 Tests of the Founder-flush Speciation Hypothesis Using Drosophila
The founder-flush (a.k.a. flush-crash) hypothesis posits that genetic drift and founder effects play a major role in speciation (Powell 1978). During a founder-flush cycle a new habitat is colonized by a small number of individuals (e.g. one inseminated female). The population rapidly expands (the flush phase). This is followed by the population crashing. During this crash period the population experiences strong genetic drift. The population undergoes another rapid expansion followed by another crash. This cycle repeats several times. Reproductive isolation is produced as a byproduct of genetic drift.
Dodd and Powell (1985) tested this hypothesis using D. pseudoobscura. A large, heterogeneous population was allowed to grow rapidly in a very large population cage. Twelve experimental populations were derived from this population from single pair matings. These populations were allowed to flush. Fourteen months later, mating tests were performed among the twelve populations. No postmating isolation was seen. One cross showed strong behavioral isolation. The populations underwent three more flush-crash cycles. Forty-four months after the start of the experiment (and fifteen months after the last flush) the populations were again tested. Once again, no postmating isolation was seen. Three populations showed behavioral isolation in the form of positive assortative mating. Later tests between 1980 and 1984 showed that the isolation persisted, though it was weaker in some cases.
Galina, et al. (1993) performed similar experiments with D. pseudoobscura. Mating tests between populations that underwent flush-crash cycles and their ancestral populations showed 8 cases of positive assortative mating out of 118 crosses. They also showed 5 cases of negative assortative mating (i.e. the flies preferred to mate with flies of the other strain). Tests among the founder-flush populations showed 36 cases of positive assortative mating out of 370 crosses. These tests also found 4 cases of negative assortative mating. Most of these mating preferences did not persist over time. Galina, et al. concluded that the founder-flush protocol yields reproductive isolation only as a rare and erratic event.
Ahearn (1980) applied the founder-flush protocol to D. silvestris. Flies from a line of this species underwent several flush-crash cycles. They were tested in mate choice experiments against flies from a continuously large population. Female flies from both strains preferred to mate with males from the large population. Females from the large population would not mate with males from the founder flush population. An asymmetric reproductive isolation was produced.
In a three year experiment, Ringo, et al. (1985) compared the effects of a founder-flush protocol to the effects of selection on various traits. A large population of D. simulans was created from flies from 69 wild caught stocks from several locations. Founder-flush lines and selection lines were derived from this population. The founder-flush lines went through six flush-crash cycles. The selection lines experienced equal intensities of selection for various traits. Mating test were performed between strains within a treatment and between treatment strains and the source population. Crosses were also checked for postmating isolation. In the selection lines, 10 out of 216 crosses showed positive assortative mating (2 crosses showed negative assortative mating). They also found that 25 out of 216 crosses showed postmating isolation. Of these, 9 cases involved crosses with the source population. In the founder-flush lines 12 out of 216 crosses showed positive assortative mating (3 crosses showed negative assortative mating). Postmating isolation was found in 15 out of 216 crosses, 11 involving the source population. They concluded that only weak isolation was found and that there was little difference between the effects of natural selection and the effects of genetic drift.
A final test of the founder-flush hypothesis will be described with the housefly cases below.
5.4 Housefly Speciation Experiments
5.4.1 A Test of the Founder-flush Hypothesis Using Houseflies
Meffert and Bryant (1991) used houseflies to test whether bottlenecks in populations can cause permanent alterations in courtship behavior that lead to premating isolation. They collected over 100 flies of each sex from a landfill near Alvin, Texas. These were used to initiate an ancestral population. From this ancestral population they established six lines. Two of these lines were started with one pair of flies, two lines were started with four pairs of flies and two lines were started with sixteen pairs of flies. These populations were flushed to about 2,000 flies each. They then went through five bottlenecks followed by flushes. This took 35 generations. Mate choice tests were performed. One case of positive assortative mating was found. One case of negative assortative mating was also found.
5.4.2 Selection for Geotaxis with and without Gene Flow
Soans, et al. (1974) used houseflies to test Pimentel's model of speciation. This model posits that speciation requires two steps. The first is the formation of races in subpopulations. This is followed by the establishment of reproductive isolation. Houseflies were subjected to intense divergent selection on the basis of positive and negative geotaxis. In some treatments no gene flow was allowed, while in others there was 30% gene flow. Selection was imposed by placing 1000 flies into the center of a 108 cm vertical tube. The first 50 flies that reached the top and the first 50 flies that reached the bottom were used to found positively and negatively geotactic populations. Four populations were established:
Population A + geotaxis, no gene flow
Population B - geotaxis, no gene flow
Population C + geotaxis, 30% gene flow
Population D - geotaxis, 30% gene flow
Selection was repeated within these populations each generations. After 38 generations the time to collect 50 flies had dropped from 6 hours to 2 hours in Pop A, from 4 hours to 4 minutes in Pop B, from 6 hours to 2 hours in Pop C and from 4 hours to 45 minutes in Pop D. Mate choice tests were performed. Positive assortative mating was found in all crosses. They concluded that reproductive isolation occurred under both allopatric and sympatric conditions when very strong selection was present.
Hurd and Eisenberg (1975) performed a similar experiment on houseflies using 50% gene flow and got the same results.
5.5 Speciation Through Host Race Differentiation
Recently there has been a lot of interest in whether the differentiation of an herbivorous or parasitic species into races living on different hosts can lead to sympatric speciation. It has been argued that in animals that mate on (or in) their preferred hosts, positive assortative mating is an inevitable byproduct of habitat selection (Rice 1985; Barton, et al. 1988). This would suggest that differentiated host races may represent incipient species.
5.5.1 Apple Maggot Fly (Rhagoletis pomonella)
Rhagoletis pomonella is a fly that is native to North America. Its normal host is the hawthorn tree. Sometime during the nineteenth century it began to infest apple trees. Since then it has begun to infest cherries, roses, pears and possibly other members of the rosaceae. Quite a bit of work has been done on the differences between flies infesting hawthorn and flies infesting apple. There appear to be differences in host preferences among populations. Offspring of females collected from on of these two hosts are more likely to select that host for oviposition (Prokopy et al. 1988). Genetic differences between flies on these two hosts have been found at 6 out of 13 allozyme loci (Feder et al. 1988, see also McPheron et al. 1988). Laboratory studies have shown an asynchrony in emergence time of adults between these two host races (Smith 1988). Flies from apple trees take about 40 days to mature, whereas flies from hawthorn trees take 54-60 days to mature. This makes sense when we consider that hawthorn fruit tends to mature later in the season that apples. Hybridization studies show that host preferences are inherited, but give no evidence of barriers to mating. This is a very exciting case. It may represent the early stages of a sympatric speciation event (considering the dispersal of R. pomonella to other plants it may even represent the beginning of an adaptive radiation). It is important to note that some of the leading researchers on this question are urging caution in interpreting it. Feder and Bush (1989) stated:
"Hawthorn and apple "host races" of R. pomonella may therefore represent incipient species. However, it remains to be seen whether host-associated traits can evolve into effective enough barriers to gene flow to result eventually in the complete reproductive isolation of R. pomonella populations."
5.5.2 Gall Former Fly (Eurosta solidaginis)
Eurosta solidaginis is a gall forming fly that is associated with goldenrod plants. It has two hosts: over most of its range it lays its eggs in Solidago altissima, but in some areas it uses S. gigantea as its host. Recent electrophoretic work has shown that the genetic distances among flies from different sympatric hosts species are greater than the distances among flies on the same host in different geographic areas (Waring et al. 1990). This same study also found reduced variability in flies on S. gigantea. This suggests that some E. solidaginis have recently shifted hosts to this species. A recent study has compared reproductive behavior of the flies associated with the two hosts (Craig et al. 1993). They found that flies associated with S. gigantea emerge earlier in the season than flies associated with S. altissima. In host choice experiments, each fly strain ovipunctured its own host much more frequently than the other host. Craig et al. (1993) also performed several mating experiments. When no host was present and females mated with males from either strain, if males from only one strain were present. When males of both strains were present, statistically significant positive assortative mating was seen. In the presence of a host, assortative mating was also seen. When both hosts and flies from both populations were present, females waited on the buds of the host that they are normally associated with. The males fly to the host to mate. Like the Rhagoletis case above, this may represent the beginning of a sympatric speciation.
5.6 Flour Beetles (Tribolium castaneum)
Halliburton and Gall (1981) established a population of flour beetles collected in Davis, California. In each generation they selected the 8 lightest and the 8 heaviest pupae of each sex. When these 32 beetles had emerged, they were placed together and allowed to mate for 24 hours. Eggs were collected for 48 hours. The pupae that developed from these eggs were weighed at 19 days. This was repeated for 15 generations. The results of mate choice tests between heavy and light beetles was compared to tests among control lines derived from randomly chosen pupae. Positive assortative mating on the basis of size was found in 2 out of 4 experimental lines.
5.7 Speciation in a Lab Rat Worm, Nereis acuminata
In 1964 five or six individuals of the polychaete worm, Nereis acuminata, were collected in Long Beach Harbor, California. These were allowed to grow into a population of thousands of individuals. Four pairs from this population were transferred to the Woods Hole Oceanographic Institute. For over 20 years these worms were used as test organisms in environmental toxicology. From 1986 to 1991 the Long Beach area was searched for populations of the worm. Two populations, P1 and P2, were found. Weinberg, et al. (1992) performed tests on these two populations and the Woods Hole population (WH) for both postmating and premating isolation. To test for postmating isolation, they looked at whether broods from crosses were successfully reared. The results below give the percentage of successful rearings for each group of crosses.
WH × WH - 75%
P1 × P1 - 95%
P2 × P2 - 80%
P1 × P2 - 77%
WH × P1 - 0%
WH × P2 - 0%
They also found statistically significant premating isolation between the WH population and the field populations. Finally, the Woods Hole population showed slightly different karyotypes from the field populations.
5.8 Speciation Through Cytoplasmic Incompatability Resulting from the Presence of a Parasite or Symbiont
In some species the presence of intracellular bacterial parasites (or symbionts) is associated with postmating isolation. This results from a cytoplasmic incompatability between gametes from strains that have the parasite (or symbiont) and stains that don't. An example of this is seen in the mosquito Culex pipiens (Yen and Barr 1971). Compared to within strain matings, matings between strains from different geographic regions may may have any of three results: These matings may produce a normal number of offspring, they may produce a reduced number of offspring or they may produce no offspring. Reciprocal crosses may give the same or different results. In an incompatible cross, the egg and sperm nuclei fail to unite during fertilization. The egg dies during embryogenesis. In some of these strains, Yen and Barr (1971) found substantial numbers of Rickettsia-like microbes in adults, eggs and embryos. Compatibility of mosquito strains seems to be correlated with the strain of the microbe present. Mosquitoes that carry different strains of the microbe exhibit cytoplasmic incompatibility; those that carry the same strain of microbe are interfertile.
Similar phenomena have been seen in a number of other insects. Microoganisms are seen in the eggs of both Nasonia vitripennis and N. giraulti. These two species do not normally hybridize. Following treatment with antibiotics, hybrids occur between them (Breeuwer and Werren 1990). In this case, the symbiont is associated with improper condensation of host chromosomes.
For more examples and a critical review of this topic, see Thompson 1987.
5.9 A Couple of Ambiguous Cases
So far the BSC has applied to all of the experiments discussed. The following are a couple of major morphological changes produced in asexual species. Do these represent speciation events? The answer depends on how species is defined.
5.9.1 Coloniality in Chlorella vulgaris
Boraas (1983) reported the induction of multicellularity in a strain of Chlorella pyrenoidosa (since reclassified as C. vulgaris) by predation. He was growing the unicellular green alga in the first stage of a two stage continuous culture system as for food for a flagellate predator, Ochromonas sp., that was growing in the second stage. Due to the failure of a pump, flagellates washed back into the first stage. Within five days a colonial form of the Chlorella appeared. It rapidly came to dominate the culture. The colony size ranged from 4 cells to 32 cells. Eventually it stabilized at 8 cells. This colonial form has persisted in culture for about a decade. The new form has been keyed out using a number of algal taxonomic keys. They key out now as being in the genus Coelosphaerium, which is in a different family from Chlorella.
5.9.2 Morphological Changes in Bacteria
Shikano, et al. (1990) reported that an unidentified bacterium underwent a major morphological change when grown in the presence of a ciliate predator. This bacterium's normal morphology is a short (1.5 um) rod. After 8 - 10 weeks of growing with the predator it assumed the form of long (20 um) cells. These cells have no cross walls. Filaments of this type have also been produced under circumstances similar to Boraas' induction of multicellularity in Chlorella. Microscopic examination of these filaments is described in Gillott et al. (1993). Multicellularity has also been produced in unicellular bacterial by predation (Nakajima and Kurihara 1994). In this study, growth in the presence of protozoal grazers resulted in the production of chains of bacterial cells.
The following are several examples of observations of speciation.
5.1 Speciations Involving Polyploidy, Hybridization or Hybridization Followed by Polyploidization.
5.1.1 Plants
(See also the discussion in de Wet 1971).
5.1.1.1 Evening Primrose (Oenothera gigas)
While studying the genetics of the evening primrose, Oenothera lamarckiana, de Vries (1905) found an unusual variant among his plants. O. lamarckiana has a chromosome number of 2N = 14. The variant had a chromosome number of 2N = 28. He found that he was unable to breed this variant with O. lamarckiana. He named this new species O. gigas.
5.1.1.2 Kew Primrose (Primula kewensis)
Digby (1912) crossed the primrose species Primula verticillata and P. floribunda to produce a sterile hybrid. Polyploidization occurred in a few of these plants to produce fertile offspring. The new species was named P. kewensis. Newton and Pellew (1929) note that spontaneous hybrids of P. verticillata and P. floribunda set tetraploid seed on at least three occasions. These happened in 1905, 1923 and 1926.
5.1.1.3 Tragopogon
Owenby (1950) demonstrated that two species in this genus were produced by polyploidization from hybrids. He showed that Tragopogon miscellus found in a colony in Moscow, Idaho was produced by hybridization of T. dubius and T. pratensis. He also showed that T. mirus found in a colony near Pullman, Washington was produced by hybridization of T. dubius and T. porrifolius. Evidence from chloroplast DNA suggests that T. mirus has originated independently by hybridization in eastern Washington and western Idaho at least three times (Soltis and Soltis 1989). The same study also shows multiple origins for T. micellus.
5.1.1.4 Raphanobrassica
The Russian cytologist Karpchenko (1927, 1928) crossed the radish, Raphanus sativus, with the cabbage, Brassica oleracea. Despite the fact that the plants were in different genera, he got a sterile hybrid. Some unreduced gametes were formed in the hybrids. This allowed for the production of seed. Plants grown from the seeds were interfertile with each other. They were not interfertile with either parental species. Unfortunately the new plant (genus Raphanobrassica) had the foliage of a radish and the root of a cabbage.
5.1.1.5 Hemp Nettle (Galeopsis tetrahit)
A species of hemp nettle, Galeopsis tetrahit, was hypothesized to be the result of a natural hybridization of two other species, G. pubescens and G. speciosa (Muntzing 1932). The two species were crossed. The hybrids matched G. tetrahit in both visible features and chromosome morphology.
5.1.1.6 Madia citrigracilis
Along similar lines, Clausen et al. (1945) hypothesized that Madia citrigracilis was a hexaploid hybrid of M. gracilis and M. citriodora As evidence they noted that the species have gametic chromosome numbers of n = 24, 16 and 8 respectively. Crossing M. gracilis and M. citriodora resulted in a highly sterile triploid with n = 24. The chromosomes formed almost no bivalents during meiosis. Artificially doubling the chromosome number using colchecine produced a hexaploid hybrid which closely resembled M. citrigracilis and was fertile.
5.1.1.7 Brassica
Frandsen (1943, 1947) was able to do this same sort of recreation of species in the genus Brassica (cabbage, etc.). His experiments showed that B. carinata (n = 17) may be recreated by hybridizing B. nigra (n = 8) and B. oleracea, B. juncea (n = 18) may be recreated by hybridizing B. nigra and B. campestris (n = 10), and B. napus (n = 19) may be recreated by hybridizing B. oleracea and B. campestris.
5.1.1.8 Maidenhair Fern (Adiantum pedatum)
Rabe and Haufler (1992) found a naturally occurring diploid sporophyte of maidenhair fern which produced unreduced (2N) spores. These spores resulted from a failure of the paired chromosomes to dissociate during the first division of meiosis. The spores germinated normally and grew into diploid gametophytes. These did not appear to produce antheridia. Nonetheless, a subsequent generation of tetraploid sporophytes was produced. When grown in the lab, the tetraploid sporophytes appear to be less vigorous than the normal diploid sporophytes. The 4N individuals were found near Baldwin City, Kansas.
5.1.1.9 Woodsia Fern (Woodsia abbeae)
Woodsia abbeae was described as a hybrid of W. cathcariana and W. ilvensis (Butters 1941). Plants of this hybrid normally produce abortive sporangia containing inviable spores. In 1944 Butters found a W. abbeae plant near Grand Portage, Minn. that had one fertile frond (Butters and Tryon 1948). The apical portion of this frond had fertile sporangia. Spores from this frond germinated and grew into prothallia. About six months after germination sporophytes were produced. They survived for about one year. Based on cytological evidence, Butters and Tryon concluded that the frond that produced the viable spores had gone tetraploid. They made no statement as to whether the sporophytes grown produced viable spores.
5.1.2 Animals
Speciation through hybridization and/or polyploidy has long been considered much less important in animals than in plants [[[refs.]]]. A number of reviews suggest that this view may be mistaken. (Lokki and Saura 1980; Bullini and Nascetti 1990; Vrijenhoek 1994). Bullini and Nasceti (1990) review chromosomal and genetic evidence that suggest that speciation through hybridization may occur in a number of insect species, including walking sticks, grasshoppers, blackflies and cucurlionid beetles. Lokki and Saura (1980) discuss the role of polyploidy in insect evolution. Vrijenhoek (1994) reviews the literature on parthenogenesis and hybridogenesis in fish. I will tackle this topic in greater depth in the next version of this document.
5.2 Speciations in Plant Species not Involving Hybridization or Polyploidy
5.2.1 Stephanomeira malheurensis
Gottlieb (1973) documented the speciation of Stephanomeira malheurensis. He found a single small population (< 250 plants) among a much larger population (> 25,000 plants) of S. exigua in Harney Co., Oregon. Both species are diploid and have the same number of chromosomes (N = 8). S. exigua is an obligate outcrosser exhibiting sporophytic self-incompatibility. S. malheurensis exhibits no self-incompatibility and self-pollinates. Though the two species look very similar, Gottlieb was able to document morphological differences in five characters plus chromosomal differences. F1 hybrids between the species produces only 50% of the seeds and 24% of the pollen that conspecific crosses produced. F2 hybrids showed various developmental abnormalities.
5.2.2 Maize (Zea mays)
Pasterniani (1969) produced almost complete reproductive isolation between two varieties of maize. The varieties were distinguishable by seed color, white versus yellow. Other genetic markers allowed him to identify hybrids. The two varieties were planted in a common field. Any plant's nearest neighbors were always plants of the other strain. Selection was applied against hybridization by using only those ears of corn that showed a low degree of hybridization as the source of the next years seed. Only parental type kernels from these ears were planted. The strength of selection was increased each year. In the first year, only ears with less than 30% intercrossed seed were used. In the fifth year, only ears with less than 1% intercrossed seed were used. After five years the average percentage of intercrossed matings dropped from 35.8% to 4.9% in the white strain and from 46.7% to 3.4% in the yellow strain.
5.2.3 Speciation as a Result of Selection for Tolerance to a Toxin: Yellow Monkey Flower (Mimulus guttatus)
At reasonably low concentrations, copper is toxic to many plant species. Several plants have been seen to develop a tolerance to this metal (Macnair 1981). Macnair and Christie (1983) used this to examine the genetic basis of a postmating isolating mechanism in yellow monkey flower. When they crossed plants from the copper tolerant "Copperopolis" population with plants from the nontolerant "Cerig" population, they found that many of the hybrids were inviable. During early growth, just after the four leaf stage, the leaves of many of the hybrids turned yellow and became necrotic. Death followed this. This was seen only in hybrids between the two populations. Through mapping studies, the authors were able to show that the copper tolerance gene and the gene responsible for hybrid inviability were either the same gene or were very tightly linked. These results suggest that reproductive isolation may require changes in only a small number of genes.
5.3 The Fruit Fly Literature
5.3.1 Drosophila paulistorum
Dobzhansky and Pavlovsky (1971) reported a speciation event that occurred in a laboratory culture of Drosophila paulistorum sometime between 1958 and 1963. The culture was descended from a single inseminated female that was captured in the Llanos of Colombia. In 1958 this strain produced fertile hybrids when crossed with conspecifics of different strains from Orinocan. From 1963 onward crosses with Orinocan strains produced only sterile males. Initially no assortative mating or behavioral isolation was seen between the Llanos strain and the Orinocan strains. Later on Dobzhansky produced assortative mating (Dobzhansky 1972).
5.3.2 Disruptive Selection on Drosophila melanogaster
Thoday and Gibson (1962) established a population of Drosophila melanogaster from four gravid females. They applied selection on this population for flies with the highest and lowest numbers of sternoplural chaetae (hairs). In each generation, eight flies with high numbers of chaetae were allowed to interbreed and eight flies with low numbers of chaetae were allowed to interbreed. Periodically they performed mate choice experiments on the two lines. They found that they had produced a high degree of positive assortative mating between the two groups. In the decade or so following this, eighteen labs attempted unsuccessfully to reproduce these results. References are given in Thoday and Gibson 1970.
5.3.3 Selection on Courtship Behavior in Drosophila melanogaster
Crossley (1974) was able to produce changes in mating behavior in two mutant strains of D. melanogaster. Four treatments were used. In each treatment, 55 virgin males and 55 virgin females of both ebony body mutant flies and vestigial wing mutant flies (220 flies total) were put into a jar and allowed to mate for 20 hours. The females were collected and each was put into a separate vial. The phenotypes of the offspring were recorded. Wild type offspring were hybrids between the mutants. In two of the four treatments, mating was carried out in the light. In one of these treatments all hybrid offspring were destroyed. This was repeated for 40 generations. Mating was carried out in the dark in the other two treatments. Again, in one of these all hybrids were destroyed. This was repeated for 49 generations. Crossley ran mate choice tests and observed mating behavior. Positive assortative mating was found in the treatment which had mated in the light and had been subject to strong selection against hybridization. The basis of this was changes in the courtship behaviors of both sexes. Similar experiments, without observation of mating behavior, were performed by Knight, et al. (1956).
5.3.4 Sexual Isolation as a Byproduct of Adaptation to Environmental Conditions in Drosophila melanogaster
Kilias, et al. (1980) exposed D. melanogaster populations to different temperature and humidity regimes for several years. They performed mating tests to check for reproductive isolation. They found some sterility in crosses among populations raised under different conditions. They also showed some positive assortative mating. These things were not observed in populations which were separated but raised under the same conditions. They concluded that sexual isolation was produced as a byproduct of selection.
5.3.5 Sympatric Speciation in Drosophila melanogaster
In a series of papers (Rice 1985, Rice and Salt 1988 and Rice and Salt 1990) Rice and Salt presented experimental evidence for the possibility of sympatric speciation. They started from the premise that whenever organisms sort themselves into the environment first and then mate locally, individuals with the same habitat preferences will necessarily mate assortatively. They established a stock population of D. melanogaster with flies collected in an orchard near Davis, California. Pupae from the culture were placed into a habitat maze. Newly emerged flies had to negotiate the maze to find food. The maze simulated several environmental gradients simultaneously. The flies had to make three choices of which way to go. The first was between light and dark (phototaxis). The second was between up and down (geotaxis). The last was between the scent of acetaldehyde and the scent of ethanol (chemotaxis). This divided the flies among eight habitats. The flies were further divided by the time of day of emergence. In total the flies were divided among 24 spatio-temporal habitats.
They next cultured two strains of flies that had chosen opposite habitats. One strain emerged early, flew upward and was attracted to dark and acetaldehyde. The other emerged late, flew downward and was attracted to light and ethanol. Pupae from these two strains were placed together in the maze. They were allowed to mate at the food site and were collected. Eye color differences between the strains allowed Rice and Salt to distinguish between the two strains. A selective penalty was imposed on flies that switched habitats. Females that switched habitats were destroyed. None of their gametes passed into the next generation. Males that switched habitats received no penalty. After 25 generations of this mating tests showed reproductive isolation between the two strains. Habitat specialization was also produced.
They next repeated the experiment without the penalty against habitat switching. The result was the same -- reproductive isolation was produced. They argued that a switching penalty is not necessary to produce reproductive isolation. Their results, they stated, show the possibility of sympatric speciation.
5.3.6 Isolation Produced as an Incidental Effect of Selection on several Drosophila species
In a series of experiments, del Solar (1966) derived positively and negatively geotactic and phototactic strains of D. pseudoobscura from the same population by running the flies through mazes. Flies from different strains were then introduced into mating chambers (10 males and 10 females from each strain). Matings were recorded. Statistically significant positive assortative mating was found.
In a separate series of experiments Dodd (1989) raised eight populations derived from a single population of D. Pseudoobscura on stressful media. Four populations were raised on a starch based medium, the other four were raised on a maltose based medium. The fly populations in both treatments took several months to get established, implying that they were under strong selection. Dodd found some evidence of genetic divergence between flies in the two treatments. He performed mate choice tests among experimental populations. He found statistically significant assortative mating between populations raised on different media, but no assortative mating among populations raised within the same medium regime. He argued that since there was no direct selection for reproductive isolation, the behavioral isolation results from a pleiotropic by-product to adaptation to the two media. Schluter and Nagel (1995) have argued that these results provide experimental support for the hypothesis of parallel speciation.
Less dramatic results were obtained by growing D. willistoni on media of different pH levels (de Oliveira and Cordeiro 1980). Mate choice tests after 26, 32, 52 and 69 generations of growth showed statistically significant assortative mating between some populations grown in different pH treatments. This ethological isolation did not always persist over time. They also found that some crosses made after 106 and 122 generations showed significant hybrid inferiority, but only when grown in acid medium.
5.3.7 Selection for Reinforcement in Drosophila melanogaster
Some proposed models of speciation rely on a process called reinforcement to complete the speciation process. Reinforcement occurs when to partially isolated allopatric populations come into contact. Lower relative fitness of hybrids between the two populations results in increased selection for isolating mechanisms. I should note that a recent review (Rice and Hostert 1993) argues that there is little experimental evidence to support reinforcement models. Two experiments in which the authors argue that their results provide support are discussed below.
Ehrman (1971) established strains of wild-type and mutant (black body) D. melanogaster. These flies were derived from compound autosome strains such that heterotypic matings would produce no progeny. The two strains were reared together in common fly cages. After two years, the isolation index generated from mate choice experiments had increased from 0.04 to 0.43, indicating the appearance of considerable assortative mating. After four years this index had risen to 0.64 (Ehrman 1973).
Along the same lines, Koopman (1950) was able to increase the degree of reproductive isolation between two partially isolated species, D. pseudoobscura and D. persimilis.
5.3.8 Tests of the Founder-flush Speciation Hypothesis Using Drosophila
The founder-flush (a.k.a. flush-crash) hypothesis posits that genetic drift and founder effects play a major role in speciation (Powell 1978). During a founder-flush cycle a new habitat is colonized by a small number of individuals (e.g. one inseminated female). The population rapidly expands (the flush phase). This is followed by the population crashing. During this crash period the population experiences strong genetic drift. The population undergoes another rapid expansion followed by another crash. This cycle repeats several times. Reproductive isolation is produced as a byproduct of genetic drift.
Dodd and Powell (1985) tested this hypothesis using D. pseudoobscura. A large, heterogeneous population was allowed to grow rapidly in a very large population cage. Twelve experimental populations were derived from this population from single pair matings. These populations were allowed to flush. Fourteen months later, mating tests were performed among the twelve populations. No postmating isolation was seen. One cross showed strong behavioral isolation. The populations underwent three more flush-crash cycles. Forty-four months after the start of the experiment (and fifteen months after the last flush) the populations were again tested. Once again, no postmating isolation was seen. Three populations showed behavioral isolation in the form of positive assortative mating. Later tests between 1980 and 1984 showed that the isolation persisted, though it was weaker in some cases.
Galina, et al. (1993) performed similar experiments with D. pseudoobscura. Mating tests between populations that underwent flush-crash cycles and their ancestral populations showed 8 cases of positive assortative mating out of 118 crosses. They also showed 5 cases of negative assortative mating (i.e. the flies preferred to mate with flies of the other strain). Tests among the founder-flush populations showed 36 cases of positive assortative mating out of 370 crosses. These tests also found 4 cases of negative assortative mating. Most of these mating preferences did not persist over time. Galina, et al. concluded that the founder-flush protocol yields reproductive isolation only as a rare and erratic event.
Ahearn (1980) applied the founder-flush protocol to D. silvestris. Flies from a line of this species underwent several flush-crash cycles. They were tested in mate choice experiments against flies from a continuously large population. Female flies from both strains preferred to mate with males from the large population. Females from the large population would not mate with males from the founder flush population. An asymmetric reproductive isolation was produced.
In a three year experiment, Ringo, et al. (1985) compared the effects of a founder-flush protocol to the effects of selection on various traits. A large population of D. simulans was created from flies from 69 wild caught stocks from several locations. Founder-flush lines and selection lines were derived from this population. The founder-flush lines went through six flush-crash cycles. The selection lines experienced equal intensities of selection for various traits. Mating test were performed between strains within a treatment and between treatment strains and the source population. Crosses were also checked for postmating isolation. In the selection lines, 10 out of 216 crosses showed positive assortative mating (2 crosses showed negative assortative mating). They also found that 25 out of 216 crosses showed postmating isolation. Of these, 9 cases involved crosses with the source population. In the founder-flush lines 12 out of 216 crosses showed positive assortative mating (3 crosses showed negative assortative mating). Postmating isolation was found in 15 out of 216 crosses, 11 involving the source population. They concluded that only weak isolation was found and that there was little difference between the effects of natural selection and the effects of genetic drift.
A final test of the founder-flush hypothesis will be described with the housefly cases below.
5.4 Housefly Speciation Experiments
5.4.1 A Test of the Founder-flush Hypothesis Using Houseflies
Meffert and Bryant (1991) used houseflies to test whether bottlenecks in populations can cause permanent alterations in courtship behavior that lead to premating isolation. They collected over 100 flies of each sex from a landfill near Alvin, Texas. These were used to initiate an ancestral population. From this ancestral population they established six lines. Two of these lines were started with one pair of flies, two lines were started with four pairs of flies and two lines were started with sixteen pairs of flies. These populations were flushed to about 2,000 flies each. They then went through five bottlenecks followed by flushes. This took 35 generations. Mate choice tests were performed. One case of positive assortative mating was found. One case of negative assortative mating was also found.
5.4.2 Selection for Geotaxis with and without Gene Flow
Soans, et al. (1974) used houseflies to test Pimentel's model of speciation. This model posits that speciation requires two steps. The first is the formation of races in subpopulations. This is followed by the establishment of reproductive isolation. Houseflies were subjected to intense divergent selection on the basis of positive and negative geotaxis. In some treatments no gene flow was allowed, while in others there was 30% gene flow. Selection was imposed by placing 1000 flies into the center of a 108 cm vertical tube. The first 50 flies that reached the top and the first 50 flies that reached the bottom were used to found positively and negatively geotactic populations. Four populations were established:
Population A + geotaxis, no gene flow
Population B - geotaxis, no gene flow
Population C + geotaxis, 30% gene flow
Population D - geotaxis, 30% gene flow
Selection was repeated within these populations each generations. After 38 generations the time to collect 50 flies had dropped from 6 hours to 2 hours in Pop A, from 4 hours to 4 minutes in Pop B, from 6 hours to 2 hours in Pop C and from 4 hours to 45 minutes in Pop D. Mate choice tests were performed. Positive assortative mating was found in all crosses. They concluded that reproductive isolation occurred under both allopatric and sympatric conditions when very strong selection was present.
Hurd and Eisenberg (1975) performed a similar experiment on houseflies using 50% gene flow and got the same results.
5.5 Speciation Through Host Race Differentiation
Recently there has been a lot of interest in whether the differentiation of an herbivorous or parasitic species into races living on different hosts can lead to sympatric speciation. It has been argued that in animals that mate on (or in) their preferred hosts, positive assortative mating is an inevitable byproduct of habitat selection (Rice 1985; Barton, et al. 1988). This would suggest that differentiated host races may represent incipient species.
5.5.1 Apple Maggot Fly (Rhagoletis pomonella)
Rhagoletis pomonella is a fly that is native to North America. Its normal host is the hawthorn tree. Sometime during the nineteenth century it began to infest apple trees. Since then it has begun to infest cherries, roses, pears and possibly other members of the rosaceae. Quite a bit of work has been done on the differences between flies infesting hawthorn and flies infesting apple. There appear to be differences in host preferences among populations. Offspring of females collected from on of these two hosts are more likely to select that host for oviposition (Prokopy et al. 1988). Genetic differences between flies on these two hosts have been found at 6 out of 13 allozyme loci (Feder et al. 1988, see also McPheron et al. 1988). Laboratory studies have shown an asynchrony in emergence time of adults between these two host races (Smith 1988). Flies from apple trees take about 40 days to mature, whereas flies from hawthorn trees take 54-60 days to mature. This makes sense when we consider that hawthorn fruit tends to mature later in the season that apples. Hybridization studies show that host preferences are inherited, but give no evidence of barriers to mating. This is a very exciting case. It may represent the early stages of a sympatric speciation event (considering the dispersal of R. pomonella to other plants it may even represent the beginning of an adaptive radiation). It is important to note that some of the leading researchers on this question are urging caution in interpreting it. Feder and Bush (1989) stated:
"Hawthorn and apple "host races" of R. pomonella may therefore represent incipient species. However, it remains to be seen whether host-associated traits can evolve into effective enough barriers to gene flow to result eventually in the complete reproductive isolation of R. pomonella populations."
5.5.2 Gall Former Fly (Eurosta solidaginis)
Eurosta solidaginis is a gall forming fly that is associated with goldenrod plants. It has two hosts: over most of its range it lays its eggs in Solidago altissima, but in some areas it uses S. gigantea as its host. Recent electrophoretic work has shown that the genetic distances among flies from different sympatric hosts species are greater than the distances among flies on the same host in different geographic areas (Waring et al. 1990). This same study also found reduced variability in flies on S. gigantea. This suggests that some E. solidaginis have recently shifted hosts to this species. A recent study has compared reproductive behavior of the flies associated with the two hosts (Craig et al. 1993). They found that flies associated with S. gigantea emerge earlier in the season than flies associated with S. altissima. In host choice experiments, each fly strain ovipunctured its own host much more frequently than the other host. Craig et al. (1993) also performed several mating experiments. When no host was present and females mated with males from either strain, if males from only one strain were present. When males of both strains were present, statistically significant positive assortative mating was seen. In the presence of a host, assortative mating was also seen. When both hosts and flies from both populations were present, females waited on the buds of the host that they are normally associated with. The males fly to the host to mate. Like the Rhagoletis case above, this may represent the beginning of a sympatric speciation.
5.6 Flour Beetles (Tribolium castaneum)
Halliburton and Gall (1981) established a population of flour beetles collected in Davis, California. In each generation they selected the 8 lightest and the 8 heaviest pupae of each sex. When these 32 beetles had emerged, they were placed together and allowed to mate for 24 hours. Eggs were collected for 48 hours. The pupae that developed from these eggs were weighed at 19 days. This was repeated for 15 generations. The results of mate choice tests between heavy and light beetles was compared to tests among control lines derived from randomly chosen pupae. Positive assortative mating on the basis of size was found in 2 out of 4 experimental lines.
5.7 Speciation in a Lab Rat Worm, Nereis acuminata
In 1964 five or six individuals of the polychaete worm, Nereis acuminata, were collected in Long Beach Harbor, California. These were allowed to grow into a population of thousands of individuals. Four pairs from this population were transferred to the Woods Hole Oceanographic Institute. For over 20 years these worms were used as test organisms in environmental toxicology. From 1986 to 1991 the Long Beach area was searched for populations of the worm. Two populations, P1 and P2, were found. Weinberg, et al. (1992) performed tests on these two populations and the Woods Hole population (WH) for both postmating and premating isolation. To test for postmating isolation, they looked at whether broods from crosses were successfully reared. The results below give the percentage of successful rearings for each group of crosses.
WH × WH - 75%
P1 × P1 - 95%
P2 × P2 - 80%
P1 × P2 - 77%
WH × P1 - 0%
WH × P2 - 0%
They also found statistically significant premating isolation between the WH population and the field populations. Finally, the Woods Hole population showed slightly different karyotypes from the field populations.
5.8 Speciation Through Cytoplasmic Incompatability Resulting from the Presence of a Parasite or Symbiont
In some species the presence of intracellular bacterial parasites (or symbionts) is associated with postmating isolation. This results from a cytoplasmic incompatability between gametes from strains that have the parasite (or symbiont) and stains that don't. An example of this is seen in the mosquito Culex pipiens (Yen and Barr 1971). Compared to within strain matings, matings between strains from different geographic regions may may have any of three results: These matings may produce a normal number of offspring, they may produce a reduced number of offspring or they may produce no offspring. Reciprocal crosses may give the same or different results. In an incompatible cross, the egg and sperm nuclei fail to unite during fertilization. The egg dies during embryogenesis. In some of these strains, Yen and Barr (1971) found substantial numbers of Rickettsia-like microbes in adults, eggs and embryos. Compatibility of mosquito strains seems to be correlated with the strain of the microbe present. Mosquitoes that carry different strains of the microbe exhibit cytoplasmic incompatibility; those that carry the same strain of microbe are interfertile.
Similar phenomena have been seen in a number of other insects. Microoganisms are seen in the eggs of both Nasonia vitripennis and N. giraulti. These two species do not normally hybridize. Following treatment with antibiotics, hybrids occur between them (Breeuwer and Werren 1990). In this case, the symbiont is associated with improper condensation of host chromosomes.
For more examples and a critical review of this topic, see Thompson 1987.
5.9 A Couple of Ambiguous Cases
So far the BSC has applied to all of the experiments discussed. The following are a couple of major morphological changes produced in asexual species. Do these represent speciation events? The answer depends on how species is defined.
5.9.1 Coloniality in Chlorella vulgaris
Boraas (1983) reported the induction of multicellularity in a strain of Chlorella pyrenoidosa (since reclassified as C. vulgaris) by predation. He was growing the unicellular green alga in the first stage of a two stage continuous culture system as for food for a flagellate predator, Ochromonas sp., that was growing in the second stage. Due to the failure of a pump, flagellates washed back into the first stage. Within five days a colonial form of the Chlorella appeared. It rapidly came to dominate the culture. The colony size ranged from 4 cells to 32 cells. Eventually it stabilized at 8 cells. This colonial form has persisted in culture for about a decade. The new form has been keyed out using a number of algal taxonomic keys. They key out now as being in the genus Coelosphaerium, which is in a different family from Chlorella.
5.9.2 Morphological Changes in Bacteria
Shikano, et al. (1990) reported that an unidentified bacterium underwent a major morphological change when grown in the presence of a ciliate predator. This bacterium's normal morphology is a short (1.5 um) rod. After 8 - 10 weeks of growing with the predator it assumed the form of long (20 um) cells. These cells have no cross walls. Filaments of this type have also been produced under circumstances similar to Boraas' induction of multicellularity in Chlorella. Microscopic examination of these filaments is described in Gillott et al. (1993). Multicellularity has also been produced in unicellular bacterial by predation (Nakajima and Kurihara 1994). In this study, growth in the presence of protozoal grazers resulted in the production of chains of bacterial cells.
^^^Exactly. I tend to think that if two creatures can produce offspring, they are of the same species. That may not perfectly match the scientific usage of the term species, but even if they have decided that some "species" can mate with other ones, that doesn't mean that all forms branch off from other forms. It doesn't mean that birds evolved from dinosaurs or humans evolved from primates. You're going to have to show me some amazing, Island of Dr. Moreau type examples. And EVEN still, you would just be showing that by manipulation we can cross vastly different species and make new hybrids, not necessarily that this means all species have evolved beginning from single-celled organisms. Maybe it wasn't fair of me to ask you of such examples. There will really be no way to prove it as fact unless humanity (or some evolved form of humans) is around in millions of years and has maintained history back to our current age. Only this way could we actually observe the evolution you propose working in a natural world.
did you read the whole thing?
it's not only about hybridization and polyploidy but also about speciation (and reproductive isolation) inside populations
do not expect anybody to show you observed macroevolution (it has been observed millions of time in the fossil record, but it seems that you don't buy it), because it takes enormous amount of time compared to humna lifespan
to think it can just happen in a few years is misunderstanding of the theory; in fact, if something like this is observed, it will be very strong evidence against evolution
what I posted were numerous examples of microevolution leading to speciation and new species
these are rare examples because first, even microevolution usually takes a long time and second, most scientists know it's a fact, so few of them will go out recording such events
still, I posted a long ass list and you're not convinced; I can only say you're a stubborn, unscientifically thinking person
Quote mining has been used by creationists for years, now you're doing the same thing
the question is asked about the last two examples where unicellular organims were investigated and the concept of a species is really vague in protozoans and not clear at all in bacteria (becasue there's no sexual reproduction)
Please, don't do this any more, it is cheating
I quoted that part about how one defines species because it shows that these classifications are not perfect. One worm may change somewhat to adapt to an environment, and someone may even decide that the outcome is a new species. Still, this does not show that everything evolved from the simplest life form. Within a group, or species, or whatever word classification, there may be changes. That is all I see being observed here. But as far as people coming from primates, for example, I see nothing but an idea. Perhaps I should have clarified what I was getting at, seeing that the word "species" may be misleading. I am not thinking different species as in worm-A and worm-B are hardly distinguishable on the outside, but have a difference in karyotypes. That is trivial changes within a worm. It does not support the idea that one vastly different animal evolved from another.
1. Once again, theory in science means something that is established and supported by a lot of evidence; it is completely different from the everyday meaning of the word and most people don't realize it
2. you wanted examples of speciation, those were all examples of speciation leading to the formation of a new species and they are only part of the observed cases
a new species is formed when reproductive isolation develops and that's exactly what they observed
the only possible conclusion is that evolution (which BTW is defined as "changes in the allele frequencies in populations with time" and I don't really know if you're able to comprehend what that means) can lead to formation of new species. According to the definition I gave you evolution has been observed hapening on countless occasions, all the time and it's still happening as we talk in the human population and every other population on this planet
I also gave you evidence for evolution leading to speciation
I don't know what more do you want and how you can claim your explanation that "Do you see, you observe it now, but it wasn't always that way" is the most logical and parsimonious explanation possible, especially considering the fossil record and the numerous examples of transition forms in it (if you want examples, I'll provide them)
2. you wanted examples of speciation, those were all examples of speciation leading to the formation of a new species and they are only part of the observed cases
a new species is formed when reproductive isolation develops and that's exactly what they observed
the only possible conclusion is that evolution (which BTW is defined as "changes in the allele frequencies in populations with time" and I don't really know if you're able to comprehend what that means) can lead to formation of new species. According to the definition I gave you evolution has been observed hapening on countless occasions, all the time and it's still happening as we talk in the human population and every other population on this planet
I also gave you evidence for evolution leading to speciation
I don't know what more do you want and how you can claim your explanation that "Do you see, you observe it now, but it wasn't always that way" is the most logical and parsimonious explanation possible, especially considering the fossil record and the numerous examples of transition forms in it (if you want examples, I'll provide them)