Meeting Abstract
The Galápagos endemic land snails of the genus Naesiotus have undergone a massive, recent radiation into 80 ecologically diverse species over the last five million years. Coupled with this increase in species number is rapid morphological diversification, including remarkable variation in coloration. One hypothesis states that this color variation is adaptive, allowing snails to avoid detection from bird predators. This hypothesis makes several testable predictions. First, birds must actually seek out and consume snails. Second, the coloration of snails will match the backgrounds they are found on. Third, birds will be unable to differentiate the colors of prey and local backgrounds. We document that Galápagos mockingbirds (genus Mimus) do in fact seek out and consume Naesiotus snails. We then compared 45 species of Naesiotus snails to local backgrounds and found that snails closely matched local backgrounds in both color and brightness. Finally, we projected snail and background color data into a bird visual space to characterize the degree of color matching from the perspective of predators. We find strong support for the hypothesis that Naesiotus snails match local backgrounds to avoid predation. The next step in this research will be to consider the unique setting of this radiation and evaluate the role coloration and other morphological variables may have played in the colonization and diversification process.
