"Species is defined as "as a group of organisms capable of interbreeding and producing fertile offspring" according to Wikipedia. Two animals are of different species if none of their offspring have ever been observed to be fertile. At least, that's a good working definition."
Just so you know: That is just about the worst definition for microbiologist. Bacteria don't grow by sexual reproduction, they reproduce by binary fission. They also share genes like crazy. I've seen a gene taken from a sargasso sea sample crop up in the database for a bacterium found in the deeps of the medeterranean ocean. There is speculation that a virus is responsible for spreading photosynthesis between several different, otherwise very distantly-related clades of bacteria.
I fully agree that bacteria, rotifers, and other creatures can pick up genes. This is incredible. In fact, they've just found bacteria that substitute entire elements, which is incredible too.
What I am asking about, is the specific hypothesis:
"all speciation occurred via repeated application of mutation and natural selection, and no other factors were involved"
Now, I realize this would be impossible to test for ALL species, but wouldn't it be nice to have an example of at least ONE species that arose in this way through sexual reproduction? We have been breeding dogs for hundreds and thousands of years, and all of them are the same species! We have been adapting plants and never been able to create new species. Why is it so hard to do it, or it's just that we haven't tried hard enough?
I'm basically taking a skeptical approach here to the hypothesis, you see what I mean? It would be nice to just call it all "evolution" and assume the results. But I'd like some proof, some falsifiable predictions that have been tested.
Certainly I can prove that macroevolution has taken place, if by that you mean that natural selection and mutation take place, and that the change is gradual, and topologically continuous.
"A unique, historical phylogenic tree" -- this pretty much expresses that idea.
But where in that paper does it talk about actual testable predictions of the hypothesis: "all speciation came about as a result of mutation and natural selection with no other factors or forces"?
Each section has a "predictions" section. But notice that even if all these predictions come true 100% of the time, this does not rule out the possibility that new species of sexually reproducing organisms are created specially by God, much like new cars are created by humans, despite there being an observably continuous change through time.
http://www.talkorigins.org/faqs/comdesc/section5.html#specia...
Look at this. We are almost there, to what I am looking for. Are these "speciation events" fitting the "mating preference" criteria or "cannot produce fertile offspring" criteria? If the latter, I am satisfied!
That's just how the scientific method works. If you're looking for certainty, this isn't where you'll find it. Science can only tell us what we think is most likely to be true based on what we can observe.
If you pick a stronger version, where they -cannot- breed, even if you were to preform in vitro or something similar on them, then we haven't quite done that yet.
[1] http://www.jstor.org/pss/2410209 (overview of attempts to record speciation in a lab)
flies - but they say only a "mating preference" was achieved. Well sure, there are different kinds of dogs and they probably prefer their own kind, but they are still just one species.
domestic cattle - this is a non-example, as the article points out, because they are all capable of interbreeding
sheep - two kinds of sheep are apparently different species. However, I would take issue with this statement: "For example, domestic sheep were created by hybridisation"... it seems inconsistent with the other one: "but the initial dates and methods of the initiation of such species are not clear". How do they know they were created by hybridisation?
They believe no such thing. Selection isn't required for allopatric speciation. Two isolated populations will naturally start to diverge just due to drift (random genetic changes over time). Given enough time they will inevitably become sexually incompatible.
"As far as I know, no new species have ever been produced, despite natural or unnatural selection."
Then let me direct you to: http://tinyurl.com/ridley2004speciation
"We begin with two distinct, but related species. The pollen of one is painted on the stigma of the other. If a hybrid offspring is generated, it is usually sterile ... However ... the chemical colchicine can often restore hybrid fertility. It does so by causing the hybrid to double its number of chromosomes ... Hybrids so produced may be interfertile with other hybrids like themselves, but not with the parental species. They are then a new reproductive species."
"Most garden varieties of irises, tulips, and dahlias, for example, are artificially created species. But their numbers are dwarfed by the huge numbers of artificial hybrid species of orchids, which it has been estimated are being formed at the rate of about 300 per month."
"Polyploid hybridization is also important in natural plant evolution."
Now, that type of speciation is a special case. It is not how animals speciate. But you are quite wrong in your quoted statement above.
"how come we take it for granted that humans, homo erectus, neanderthals etc. were all divergent species that had a common ancestor something like 50,000 years ago? Am I way off?"
Yes, you are, by an order of magnitude. Homo neanderthalensis is supposed to have diverged 500,000 - 800,000 years ago. http://dx.doi.org/10.1126/science.316.5827.967a ("The new findings also push back the date that Neandertals split from the human branch of the primate tree by 200,000 years—to 800,000 years ago")
"maybe the white->dark->white butterflies was a bad one"
Don't believe everything you read in AnswersInGenesis. This is still a good example. Or at least, so I believe on the basis of http://bostonreview.net/BR35.2/block_kitcher.php - "These are interesting alternatives to the familiar story, and the causal hypotheses they introduce can be tested in obvious ways: by examining the rates of larvae survival or by investigating nocturnal motions of moths. And this is what biologists have done."
But I don't have time to dig into the primary literature.
"scientists have been interbreeding literally thousands of generations of fruit flies and despite all selection pressures, artificial or not, were never able to produce a single new species"
Do you have examples where this has been the actual goal? I know Dodd (1989, http://eebweb.arizona.edu/courses/ecol525/readings/dodd_1989... ) tried this, but I don't think the experiment ran that long.
You will appreciate that it is much more effort for me to correct your poorly-informed naysaying than it is for you to naysay.
Although this doesn't prove that all species came about through mutation and natural selection only, it does give examples of this happening. I didn't know it happened in plants.
And thanks for setting the record straight on what people believe regarding our common ancestor with neanderthals. Offhand, I thought it was a mere 50k years :P Are there any hominids that split from us more recently? Like 50k?
I just mean selection by forces within nature and not an external factor
Is there any evidence of macro-evolution having ever taken place in recorded history? I'm asking this with no agenda, but curious. As far as I know, no new species have ever been produced, despite natural or unnatural selection.
So what makes us say that there is no other force or process that causes speciation? How are scientists so convinced that mutation and natural selection is all that is required, despite never having observed a single instance of speciation?
To be scientific, a theory has to make some potentially falsifiable, non-obvious predictions. Then we can test those predictions, and if our experiments confirm them then the theory survives. I totally agree that the hypothesis "natural selection occurs" has been proven in ample ways (ok, maybe the white->dark->white butterflies was a bad one, but bacteria and their resistance to antibiotics is proof enough). But to form a completely new species...
Species is defined as "as a group of organisms capable of interbreeding and producing fertile offspring" according to Wikipedia. Two animals are of different species if none of their offspring have ever been observed to be fertile. At least, that's a good working definition.
It bothers me that scientists have been interbreeding literally thousands of generations of fruit flies and despite all selection pressures, artificial or not, were never able to produce a single new species. Sure, it's hard to try and mate every fruit fly with every other fruit fly, so maybe there were divergent species, but after a few generations, this should have revealed itself. If this is really the case, then how come we take it for granted that humans, homo erectus, neanderthals etc. were all divergent species that had a common ancestor something like 50,000 years ago? Am I way off? If you take the fruit fly lifetimes and human lifetimes, in those 50,000 years we had about as many generations as the fruit fly generations. And we got all this speciation supposedly, using nothing more than mutation and natural selection. But where is the proof?
I'm not necessary arguing that one of the religions is right and there is another force. But are scientists being biased here when they simply assume there isn't any other force? It's as if I was looking at cars from the 1920s all the way up until now, and I saw gradual change, and based on this I decided that there was no designer of these cars. I don't think that follows at all.
Just curious if someone knows links that can resolve this for me :)