Galapagos finches

I like how creationists still act surprised to learn that it's considerably difficult to determine when a new species has emerged. In Darwinian terms, a species is just convenient shorthand that stands in for a distinction that only a creationist thinks should be straightforward. Creationism, as far as anyone can tell, alleges that certain forms of life may share ancestry, only no one's been able to determine how much. The theory of common descent asserts that all life shares ancestry, so all differences are matters of degree and never of essence.The Galapagos finches are fascinating for the fact that they show how a formerly unified population has exploited separate niches and developed structures and instincts best suited to their individual environments. The effect of geographical distribution on the rate of speciation is dramatic and persuasive to any rational observer. Unfortunately, creationists have a vested interest in denying that speciation events take place, and for that reason only, they can't consider the finches separate species.Regardless of the designation of species or subspecies, it's quite obvious that evolution by natural selection has been responsible for a significant amount of observable variation in descendants of fairly recent common ancestors. Creationists never tire of telling us that the Galapagos finches tell us nothing about the mechanisms of evolution, that this isn't Darwinian evolution at all, and that we should ignore the clear lessons these birds teach us about the development of life on Earth.

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The dark nursery of evolution is very dark indeed.
Brad McFall

Tamara,The lack of a solid definition for 'species' is just what we expect from a Darwinian standpoint. The difference between humans and chimps is a matter of degree, just like the difference between the species of Galapagos finches, the dozens of species of leopard frog, or the thousands of species of tapeworm. This comes as no surprise to taxonomists, zoologists, or anyone who sees the development of life on Earth through the lens of evolution.Perhaps you could let us all know how natural selection resulted in changes in allele frequency in the Galapagos finches, but that evolution by natural selection is somehow flawed or fraudulent. We see the changes wrought by natural selection, and we see the vast amount of change in organisms over time. Why shouldn't one type of change be the basis for the other?

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The dark nursery of evolution is very dark indeed.
Brad McFall

Tamara,Again, I'm not sure what you demand to see. I apologize that evolution from Cambrian forms to modern ones is too slow to demonstrate in a lab, but too fast to be captured perfectly in the fossil record. If this seems like rationalization to you, so be it. Your healthy skepticism goes out the window when Wells and Milton are doing the talking.You seem to realize that 'species' will never have a precise definition, but you don't seem to understand our explanations of why this is necessarily so. If you think of a better definition, you may win a Nobel prize.You seem to realize why the finches are such an important demostration of adaptive radiation, but you'd rather not put that together with the genetic links we recognize between ostensibly unrelated organisms. In other words, the fingerprints of evolution are everywhere but you want us to believe evolution isn't.[This message has been edited by MrHambre, 02-09-2004]

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The dark nursery of evolution is very dark indeed.
Brad McFall

Tamara,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.Evolutionary theory claims that chimps and humans descended from a common ancestor. However, it denies that there is a magical point where humans acquired their human-ness and chimpanzees acquired their chimp-ness. There are no magic thresholds that organisms cross that make them a different species. The point of all this is the change itself that we see among the different members of populations, that constitutes evolution's first steps. Call it microevolution or adaptation, but it's evolution nonetheless.

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The dark nursery of evolution is very dark indeed.
Brad McFall

Syamsu, is that you?

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The dark nursery of evolution is very dark indeed.
Brad McFall

Tamara,Actually, the research shows that during nice wet weather in the Galapagos (muchas gracias, El Nio), the hybrids proliferated. It seems there was plenty of vegetation, and no real incentive to specialize. Unfortunately, once the droughts returned, the hybrids dwindled. It seems the exploitation of individual ecological niches is a Good Move, and (as Darwin predicted) evolution rewards this specialization during times when the limited resource base of a population creates a struggle for existence.Incidentally, could I bother you to hit the 'reply' button at the bottom of the post to which you're replying? It makes it easier for us to know which poster you're addressing.

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The dark nursery of evolution is very dark indeed.
Brad McFall

Tamara,Again, I wonder what you're getting at. Could you tell us whether you believe speciation has ever taken place? Should all organisms be classified as the same species just because laymen aren't comfortable with the amount of ambiguity in the definition of species?Do you have a problem with the notion of common ancestry? If so, could you tell us what it is? Do you believe that certain groups of organisms popped into existence out of thin air?Could you please tell us what the best explanation could be for the nested hierarchies we observe in life on Earth? Or why the family trees scientists have assembled using various methods all seem to correlate to a high degree?

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The dark nursery of evolution is very dark indeed.
Brad McFall