Darwin’s finches are a classic and historically important example of a species radiation (sometimes called an “adaptive” radiation, but that implies a specific assertion about the cause of the radiation which may not be appropriate in all cases). During the five weeks that Darwin spent on the Galapagos in September, 1835, he made a number of observations of these birds, but they did not occupy his time or attention more than any other aspect of this remarkable archipelago of islands. It seems that Darwin did not recognize all of the finches as finches, thinking some were of an entirely different group of birds, and in some cases, the variety seen across some of 13 or so species was initially interpreted by Darwin to represent a notably large range of variation in a single species. Please remember, Darwin was a rock man more than he was a bird man, at the time.

John Gould was a bird man, the most famous of his time at least in England, and he is the one who re-identified specimens mistaken by Darwin to be three or four different kinds (blackbirds, grosbeaks, and finches) as representing about a dozen different finches that had diversified into distinctly different forms.

There is even a Vampire Finch. And, even more amazingly, there is a Vampire Finch Movie!(click here to find out more…)

There are two separate dimensions to variation in these finches. The overarching pattern is that different species are found on different islands, owing to a combination of genetic drift and local adaptation, the other is that different finches living in overlapping geographical ranges had different adaptations for differing diets. One gets the impression that Darwin was struck more by this first aspect of variation than the second. This pattern of variation … island by island … also applied to other animals such as the tortoises.

The phrase “Darwin’s Finches” was first advanced, or at least popularized, by David Lack, the famous ornithologist who also advanced a version of group selection theory, in the 1940s.

Here is a list of the species cribbed from Wikipedia: Continue reading Charles Darwin Bicentennial – Finches →