Evolution of Coloration and Mate Preferences Along Resource Availability Gradients

University Of California-Los Angeles, Los Angeles CA

Investigators

Abstract

Evolution of coloration and mate preferences along resource availability gradients Gregory Frank Grether (PI) Gita Raman Kolluru (co-P) The only barriers to reproduction between some closely related species are female mate preferences for male secondary sexual characters. Factors that cause female mate preferences to evolve (i.e., change over generations) can lead to the formation of new species. Scientists are just beginning to understand the role of the environment in this process. In guppies, a small stream-dwelling fish native to Trinidad, females prefer males with larger and "brighter" orange spots. The orange spots contain two types of pigments, one which males can synthesize (drosopterins) and another which they must ingest (carotenoids). Guppies acquire carotenoids from algae, which grow on rocks in the streambed. Algae availability for guppies is strongly influenced by forest canopy cover and therefore by stream width (wider streams create larger gaps in the forest). The proposed project will expand and strengthen efforts to understand how variation among streams in forest canopy cover affects the evolution of male coloration and female mate preferences. In addition, new experiments will be carried out to determine (1) whether carotenoid consumption influences parasite resistance, (2) whether transfer of carotenoids from mothers to offspring affects offspring viability, and (3) whether males also express carotenoid-based mate preferences. The methods will include field experiments, laboratory breeding experiments, color measurements and biochemical analyses. The broader goal is to develop a deeper understanding of how the environment affects the evolution of mate preferences and the traits they favor. This study will contribute to our knowledge of biological diversity.