DISSERTATION RESEARCH: Mate choice, genetic variation and population structure in hybrid zones

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Behavioral decisions are important mechanisms that can prevent interbreeding of species, and are critical to the evolutionary fate of natural hybrids. The project seeks to understand how these behavioral decisions affect the genetics of populations. Single nucleotide differences in DNA sequences between two species of neotropical stream fish will be used to study the genetics of hybrid populations in an area of Mexico where the two species hybridize in the wild. Since hybrid fish are sometimes difficult to visually distinguish from parent species, this molecular approach will enable investigators to identify fish as hybrid or parent species. Knowing the species identity of individuals will allow the investigators to examine behavioral decisions by determining who females mate with (mate choice decisions) and who individuals spend time with (social decisions), as well as whether there are differences in post-birth survival among hybrids and pure parentals in these livebearing fish. Preliminary results suggest that behavioral decisions may be more important in shaping the genetics of populations than is selection against hybrid fish. Further molecular work will allow more in-depth analyses of behavior and genetic patterns. This work will build and expand upon understanding the contributions of both pre-mating behavior (social decisions and mate choice decisions) and post-mating behavior (differential fertilization of eggs and natural selection) to the fate of natural hybrids, reproductive isolation of species and speciation. The project and investigators will accomplish outreach through the CICHAZ field station in Mexico via electronic media and mentoring of a Mexican student in molecular techniques in addition to continuing to foster internationally collaborative projects.