Evolution of Reproductive Isolation in Cyprinodon

University Of New Mexico, Albuquerque NM

Investigators

Abstract

PROJECT SUMMARY Evolution of reproductive isolation in Cyprinodon Astrid Kodric-Brown Understanding processes that create and maintain species is a fundamental goal of modern biology. The proposed research will examine the roles of behavior, ecology, and offspring fitness in limiting hybridization between a native, endangered species, the Comanche Springs pupfish and an exotic species, the sheepshead minnow. The two species were geographically isolated, but have recently been brought into physical contact due to human activities. The proposed research seeks to identify the reproductive barriers that limit matings between individuals of the two species, and affect the viability and fertility of hybrid offspring. The strength of reproductive barriers will be determined by observing matings between Comanche Springs pupfish, sheepshead minnow, and their hybrids in artificial ponds. Preferences of Comanche Springs pupfish, sheepshead minnow and hybrid females will be tested by examining the responses of females to simultaneous presentations of visual and olfactory cues from each type of male. Male-male interactions will also be observed to determine species-specific differences in male mating behavior or competitive ability. The viability of hybrids will be determined by comparing the number of offspring produced by intraspecific and interspecific matings, then rearing the offspring under standardized conditions to compare growth rates, mortality, and sex ratio. The results of the proposed study will elucidate mechanisms that promote the divergence between lineages and contribute to understanding the resistance or susceptibility to hybridization in North American freshwater fishes. The project will contribute to training of graduate and undergraduate students and to informing the general public through posters and exhibits. Students will receive training in conceptual approaches as well as in experimental and field methods. The findings will be presented in posters and talks at regional and national meetings, and will be published both in professional journals and in lay publications.