Galapagos finches

Nosy, please read with care. Don't just yell wrong! All I said was that Canis lupus (whom we have not bred, per Temp's comment above) and Canis familiaris are now classed as one species.I will get back to you on the link.[This message has been edited by Tamara, 02-09-2004]

The species link says: Although the current scientific understanding of species suggests there is no principled, black and white way to distinguish between different species in all cases, biologists continue to seek concrete ways to operationalize the idea. One of the most popular biological definitions of species is in terms of reproductive isolation; if two creatures cannot reproduce to produce fertile offspring, then they are in different species. This definition captures a number of intuitive species boundaries, but nonetheless has some problems, however. It has nothing to say about species that reproduce asexually, for example, and it is very difficult to apply to extinct species. Moreover, boundaries between species are often fuzzy: there are examples where members of one population can produce fertile offspring with a second population, and members of the second population can produce fertile offspring with members of a third population, but members of the first and third population cannot produces fertile offspring. Consequently, some people reject this notion of species.
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When it comes to living birds, the two first objections are not an issue. (No matter how a species is defined, it will not solve the paleontologists’ difficulties.) The third objection I am not familiar with. Does it apply to birds? I think we are not likely to have a useful definition of a species that works for all — plants, unicellulars, everyone. But Dobzhansky’s old definition is a good one, can anyone tell me why it should not be applied to birds?

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Why are you still claiming there's a need to define 'species'? I told you that in terms of evolutionary theory, such distinctions are useful but arbitrary. Please let me know you understand this point, because the way you continue to harp on the point tells me you don't really get it.

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MrH: I would prefer if a more rigorous definition were applied, yes. I think it would be more useful. I understand that no such definition can be completely rigorous. Do you understand that if the definition of a species is so diluted that any few minor characteristics can be said to set apart a species then the argument for speciation has virtually no value for the theory of evolution? Trivializing species means trivializing speciation; in other words, all you have then left is an argument that from groups of closely related critters, there arise by selection other groups of closely related critters slightly different from the first group. Animal and plant breeders have known this for millennia, we don’t need science to tell us this.

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There are no magic thresholds that organisms cross that make them a different species.

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I am not interested in magic thresholds. I am interested in good argumentation.Coragyps: I believe that the latter part of that quote is from: Peter R Grant and B. Rosemary Grant, "Speciation and hybridization in island birds", Philosophical Transactions of the Royal Society of London B 351 (1996), pp765-772. I tried looking for it online but no luck. (I emailed you. )

I was able to access the Science article, and here are the only pertinent stuff to our discussion that I could find:
p 196
"The discovery of superior hybrid fitness over several years suggests that the three study populations of Darwin's finches [on Daphne] are fusing into a single panmictic population, and calls into question their designation as species."
p 197
"Hybridization and fluctuations in relative fitness of hybrids illustrate the challenges to our concept of species that arise from moderately rare but significant events in the real world."

NosyNed, that about sums it up. As I said, the finches would be much more persuasive as an argument if the classification were redone. Better to have two solid species than 14 iffy ones.Too bad about the gulls... I'm gonna have to rethink my suggestion. Still... it could hold apart from the anomalies... including the marginally fertile hybrids like hinnies.

Paul, when people begin to attack the person, it usually means they've run out of argument. Too bad.

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it's just an old term that was coined before people knew better and has stuck

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Stuck? Only in minds unable to learn.

Ah, Coragyps, I was wondering if I should have gone into the fusion thing. You are quite right. That, as well as any potential current speciation, seems to be a non-issue on the Galapagos -- the research shows back and forth fluctuation that seems to result in more of the same, so far.I'll watch out about quote mining (never heard the term before!). Good point.

Hi truthlover. I am not sure why people keep disecting my statement about wolves. I was reacting to what someone else had said, and all I meant was that we have not bred wolves as a species. Of course we have bred wolves to create other critters, namely dogs (with jackals possibly involved) and wolf-dog hybrids.Wolves per se, we were given.Actually, I am not sure whether coyotes have also been reclassified. I am afraid I may have overreached on this one. I will inquire of my source, for those who are interested.Humans do not vary as much as dogs, but are sufficiently multifarious to make another such example.The rest, well, we've pretty much flogged this horse all it can handle.[This message has been edited by Tamara, 02-10-2004]

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It's better to attempt accurately to count species.

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I am all for it.
Unfortunately, I don't think I'll live to see it in this case.

Truthlover, tuck in your ire. It's unbecoming.I am tired of people putting meanings into my words never meant.
I don't have many years left on this earth. I am not expecting the finches to get re-evaluated in that time. Eventually, they will.
That is all, folks.

Folks, if you think you can convince the doubters by condescencion, ad hominems, and incessant false assumptions about their point of view, then you are living in la-la-land. America is now full of people who have lost trust in darwinism. It is up to you to try to make better explanations where necessary, and to clean up the stables where necessary. Getting dug into true believerism is not going to go far. Science is not furthered by doubter-attacks, it is furthered by coming up with better and more convincing theories.I believe that evolution happened. I am distressed that there are enough holes out there to give the anti-evolutionists significant fodder for their writings. And even more distressed to see scientists so intransigent that they do not even have the class to admit that "gill slits" ought to have been left behind long ago. (I thought you were baiting me, Paul, because I thought this was a complete non-issue, that the creationists were right about it but well behind times. You have shown me otherwise.)What exactly are you waiting for, NosyNed? If you are waiting, like me, for an objective re-evaluation of the finch species, I suggest you bunker down for the long haul. It's not so much that scientific progress is gradual, which it is, and sometimes must wait for a few funerals, but that in this case, the taxonomist who would dare suggest that the finches ought to be one species would be torn and quartered as an ally of the creationists. I am afraid the job will have to await more open-minded times.And finally, I would like to add that the species definition I reposted above mentions several weaknesses of the "physiologically incompatible in breeding" sort of definition. But it does not mention its considerable strength. And that is its falsifiability. If we stick with that definition, any claim of a separate species can be overturned by the person who shows successful matings. Would that not be an improvement? In a world "ruled" by that definition, none of us would have to waste our time arguing the finches, and could go back to having a life! I thank you all for jousting with me.[This message has been edited by Tamara, 02-11-2004]

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Again, why does it matter if there are lots of finch species or one?

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If only one species, then no speciation in this case. Of course, if there are other equally vivid examples, then no problem. See my new thread on Speciation examples.

regarding the question of dog and wolf classification, here is what my contact at the university of Guelph sent. If anyone has evidence that dogs are again a separate species, I would appreciate the reference.
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I took a quick look on the web and found a couple of references to the re-classification of the domestic dog. The best is the University of Michigan site ADW: Canis lupus: INFORMATIONWhile this page is about wolves, it has a number of paper and online references at the bottom of the page that may help you in your search for dog taxonomy. According to another site, the dog was reclassified in 1993 by the Smithsonian Institute and the American Society of Mammalogists. Hope this helps you!Check out this reference; Mammal Species of the World, A Taxonomical and Geographic Reference. This is where the reclassification was originally published. As for the suggestion that the dog is once again classified as its own species, I found no reference to that in my search.

And the wolf classification page from the university of Alberta that is referenced at the bottom of the linked article says:"The domestic dog (Canis familiaris) is considered by some to be con-specific with the grey wolf, meaning that they are members of the same species. The dog is considered to be a domestic variant of the grey wolf and its latin name would be Canis lupus familiaris or Canis lupus var. familiaris. Despite this, the dog is still usually referred to as Canis familiaris. "

I have come across a mention of the finches in Margulis & Sagan's Acquiring Genomes (pp29-32):They accept the current species as defined, but argue that there is no evidence of incipient speciation. "The Darwinian paradigm is operating exactly as it should: Different traits (whether within species or among different species) are varying in prevalence according to the demands of the environment. Obviously, the genes that produce these traits are varying in like fashion. But there is no evidence that this process leads to speciation [among these finches].Speciation, whether in the remote Galapagos, in the laboratory cages of the drosophilosophers, or in the crowded sediments of the paleontologists, still has never been directly traced." Goes on to describe Dobzhansky's classic 2 fly populations as "only reproductive isolation" and not speciation.Her point, of course, is not that speciation does not go on. Her point is that the best direct cases of speciation come from the tiny critters, where two of them merge into a new organism.Cool beans!

Quetzal, she feels that the repro isolation definition of species is useful for mammals and birds. But with Dobzhansky's flies, what they had was a weird anomaly, if I recall correctly: 2 genetically identical populations that could not interbreed. I will post more if I find it.Btw, it's well worth reading. She is pretty ethused about the subject! [This message has been edited by Tamara, 02-27-2004]