Spiders, Not Birds, May Drive Evolution of Some Butterflies

Mar. 12, 2013 — Butterflies are among the most vibrant insects, with colorations sometimes designed to deflect predators. New University of Florida research shows some of these defenses may be driven by enemies one-tenth their size.

Since the time of Darwin 150 years ago, researchers have believed large predators like birds mainly influenced the evolution of coloration in butterflies. In the first behavioral study to directly test the defense mechanism of hairstreak butterflies, UF lepidopterist Andrei Sourakov found that the appearance of a false head -- a wing pattern found on hundreds of hairstreak butterflies worldwide -- was 100 percent effective against attacks from a jumping spider. The research published online March 8 in the Journal of Natural History shows small arthropods, rather than large vertebrate predators, may influence butterfly evolution.

"Everything we observe out there has been blamed on birds: aposematic coloration, mimicry and various defensive patterns like eyespots," said study author Andrei Sourakov, a collection coordinator at the Florida Museum of Natural History's McGuire Center for Lepidoptera and Biodiversity on the UF campus. "It's a big step in general and a big leap of faith to realize that a creature as tiny as a jumping spider, whose brain and life span are really small compared to birds, can actually be partially responsible for the great diversity of patterns that evolved out there among Lepidoptera and other insects."

Continued:  http://www.sciencedaily.com/releases/2013/03/130312102547.htm