Behavioral Ecology of cave dwelling and extremophile poeciliid fishes: Influence of darkness, hydrogen sulfide and low food availability on the behavior, reproductive life-history traits and sexual selection in mollies (Poecilia mexicna, P. sulphuraria) a

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Populations of Poecilia mexicana inhabit waters containing naturally occurring, toxic hydrogen sulfide, lightless underground waters or a combination of both (a sulfidic cave: Cueva del Azufre). Previous results from this project revealed pronounced genetic differentiation between the Cueva del Azufre cave fish and surrounding surface populations along with a variety of evolutionary changes regarding behavior and life history traits, suggesting local adaptation and reduced gene-flow among habitat types. I will complete my study on the genetic differentiation of a newly discovered cave form of P. mexicana from a non-sulfidic cave while using microsatellites and the cytochrome b gene as genetic markers. I will compare the behavior evolution of this cave fish (e.g., evolution of non-visual mate choice in response to darkness, potential reduction of energy-demanding behaviors) among several populations of that species with different local adaptations. Furthermore, genetic differentiation and gene-flow will be examined in another sulfidic system, the Banos del Azufre, where a morphologically very specialized poeciliid, P. sulphuraria exists, which may be considered an extreme form of a sulfide-adapted population of the very diverse "P. mexicana-group". Furthermore, I will examine associative mating in the two systems to test if pre-zygotic reproductive isolation mechanisms have evolved, thereby promoting the process of genetic differentiation accompanying local adaptation.