From “In One Species, Ten Patterns? Why Poison Dart Frogs Dress Differently” (Discover, November 8, 2011), we learn of a poisonous Peruvian frog species (not named) that features ten different colour patterns, depending on the area in which they live. Tests showed that birds avoided only the clay models that featured the local pattern. The researchers theorize that bird predation explains why the differently patterned frogs don’t interbreed, but suggest that genetic drift explains why so many wildly different patterns came to exist in the same species:
Once a certain pattern is established, it may be selected for no reason other than that it’s already present.
Ah yes, it’s the “already present” part that gives pause for thought. How did they all come to be already present? It’s the same puzzle as with horizontal gene transfer. It is an excellent method of evolution, but it requires that th newly installed parts already exist.
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