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Journal of Undergraduate Research

Keywords

female mate choice, Poecilia gillii, male dominance, intersexual selection

College

Life Sciences

Department

Biology

Abstract

Female mate choice (intersexual selection) and male dominance interactions (intrasexual selection) can each play important roles in sexual selection. These two mechanisms tend to be discussed in isolation. The goal of this study is to explore the interaction between these two forms of sexual selection. To test this idea, we focused on the livebearing tropical fish system Poecilia gillii (See Figure 1). We grouped males into similarly sized pairs and observed them for a week to determine which male was dominant. These pairs were then presented to females in mate choice trials to ascertain female preference. Our data appears to indicate that females prefer dominant males but we are still in the analysis stage. To determine the physical differences between dominant and submissive males, we are now analyzing the males for morphology and coloration. Female preference for dominant males also appears to be accompanied by the evolution of darker fin coloration and fuller bodies in these individuals. Because our initial data appears to support female preference for dominant males with these characters, mate choice and intrasexual competition are being shown to be working synergistically to enhance the evolution of sexual traits. We hope these initial findings will be confirmed as we finish collecting and analyzing the data.

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