Multiple Paternity Analysis in a Hybrid Zone

Abstract

Hybridization is an important evolutionary process. Hybrid zones can illustrate mechanisms which lead to introgression. Two live bearing freshwater fish, Xiphophorus malinche and X. birchmanni have formed several natural hybrid zones. The females of both species mate several times with several males (polyandry). Polyandry increases genetic diversity and the opportunity for sexual selection. To analyze levels of multiple paternity, we will genotype parents and offspring from one population using microsatellite markers, allowing for easy paternity assignment. Using the program GERUD, we will determine the number of sires for each female’s offspring. We expect, like parental species, that hybrid females will display a high level of multiple paternity. By studying multiple paternity in this hybrid zone; consequences of polyandry, such as increased opportunities for sperm competition or other mechanisms promoting post copulatory sexual selection, can be studied in this system in the future.