Mate Choice and Multiple Paternity in the Xiphophorus Malinche/X. Birchmanni Hybrid System

Abstract

Hybridization represents a collision of genomes that can introduce new genetic and phenotypic variation into a population. Depending on the environment, this may lead to increased individual fitness and allow for integration of novel gene combinations via gene flow between divergent species. Recent work has shown that hybridization is an important evolutionary process in terms of the diversification of species and that it is probably far more common than once thought. To further understand the process of hybridization, studies examining mating decisions can be used to predict not only how hybridization occurs in the first place but also to predict the future evolutionary path of parental and hybrid populations. Here I present two studies on Xiphophorus malinche, X. birchmanni, and their hybrids. In the first, I examine the chemical and visual preferences of male X. malinche with dichotomous choice trials; I found that, unlike females or male X. birchmanni, male X. malinche show no strong preferences in terms of chemical or visual cues. In my second study, I used microsatellite markers to determine that there is a high degree of polyandry in a subpopulation of an X. malinche and X. birchmanni hybrid zone after first investigating population structure.