Dissertation Research: Experimental Test of Ecological Speciation in a Freshwater Minnow (Cyprinidae: Lavinia).

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Bernardi0104832The investigators will determine the extent that ecological and genetic factors play on the reproductive isolation between two closely related freshwater fish species in California (Lavinia symmetricus and L. exilicauda). The two species occur together in two separate drainages: Clear Lake and Monterey Bay rivers. Levels of reproductive isolation between the two species differ in the two drainages with extensive hybridization occurring in only one of the drainages. The investigators will produce crosses between the two species in the laboratory to measure performance of the hybrids against the pure crosses. Processes that allow the formation of new species have been a central focus in biology. Groups of individuals in a rapidly radiating species that have recently become isolated can be analyzed to determine which factors are contributing to reproductive isolation. Other research has shown that there are two types of processes contributing to rapid radiations: ecological and genetic. Much of the empirical research on radiations in closely related species has focused on ecological factors. Recent work has revealed that genetic incompatibilities between closely related species may be more prevalent than believed. Results from this study will allow a greater understanding of the processes that promote speciation and diversification.