PARENT SESSION
Contributed Oral Session 61: Evolutionary Ecology: Aquatic Systems
Tuesday, August 9, 1:30 PM - 5:00 PM, Meeting Room 518 A, Level 5, Palais des congrès de Montréal

Female preferences evolve in response to divergent predation pressure in guppies (Poecilia reticulata).

Schwartz, Amy¹, Hendry, Andrew¹, ¹ McGill University, Montreal, Quebec, Canada

ABSTRACT- The ecological differentiation of populations can promote local adaptation in fitness-related traits and lead to speciation. The role of ecology is therefore essential in studies of speciation if we are to understand how, and which populations will be able to adapt to increasing levels of environmental change. Trinidadian guppy (Poecilia reticulata) populations provide a classic example of the influence of ecology on rapid adaptation. Guppy populations are exposed to divergent selection pressures as a result of variation in predator distribution patterns. Populations experiencing low and high predation risk differ dramatically from one another in a variety of traits linked to fitness. Ecological speciation theory predicts that ecologically divergent populations should show stronger reproductive isolation (reduced mating between fish from high and low predation populations) than ecologically similar populations (mating is random with respect to population type). However this prediction is difficult to test when the traits under divergent natural selection in two environments are favored through sexual selection in both environments. We studied whether divergent natural selection has led to divergent sexual selection between guppy populations. We measured female preferences for male size and color from paired high and low predation populations from three rivers. Female preference functions for male color diverged in parallel between high-and low-predation populations. The direction of divergence is consistent with the direction of male phenotype divergence: high predation males are less colorful, and high predation females consistently show a reduced or negative preference for color. Such parallel divergence in male signaling traits and female preferences suggests that differences in ecology may be contributing to the evolution of reproductive isolation in Trinidadian guppies.

Key words: natural selection, sexual selection, mate choice, reproductive isolation