The Evolution of Anoles

Over at TheScientist I found articles reporting on the evolutionary dynamics of anole lizards living on the Caribbean islands. But it turns out to be the usual bait-and-switch.

It’s not surprising that evolutionary biologists found favor with anoles since these lizards are extremely diversified, boasting over 400 different species, many originating from Central and South America.

A group of researchers collected 30 species of anoles for examination, while a separate group studied the fossils of 20 anoles preserved in amber, supposedly dating back 15 to 20 million years.

The first study refers to the way certain habitats drive speciation, pointing to competition, predators, isolation, available resources, food sources and other environmental differences. It also examines how these anoles, on different islands, underwent “convergent evolution,” achieving similar characteristics in similar environments.

After studying the fossils preserved in amber, the second group of researchers found that several types already existed, allowing the fossilized anoles to be assigned to four modern groups, called ecomorphs (a set of habitat specialists existing on more than one island, though the species in each group differ between islands). I found one of their conclusions interesting: “At least several of the habitat specialist types already existed,” said Jonathan Losos, an evolutionary ecologist at Harvard.

So, where’s the evolution? Clearly the anoles we find today are similar to the anoles that lived 20 million years ago (keep in mind humans supposedly split from chimps between 4-13 million years ago), but we haven’t seen these lizards evolve into a different kind of organism. What we have seen, however, is speciation, adaptation, gene expression and natural selection, none of which are the same thing as evolution. In fact, what we’ve observed is a process that doesn’t even need to be referred to as evolution at all, but is rather consistent with creationist claims that reject evolution. At the end of the day, all the anoles involved in the studies remained anoles.

Yes, there’s documented change, but to define evolution as change is misleading because it doesn’t distinguish between what can already be defined as natural selection or speciation, to Darwinian evolution, in which one kind of organism becomes an entirely different kind of organism (say a deer-like mammal evolving into a whale). In other words, there’s a huge difference between the offspring of anoles expressing different traits already available in their genome, to a dinosaur evolving feathers and becoming a bird.

Despite the leading headline of the article, the study has little to do with evolution.

I also attached a short video that does a nice job explaining how speciation occurs via natural selection, but such change shouldn’t be confused with evolution.


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