P1.149 Saturday, Jan. 4 15:30 A great divide: Allopatric speciation of the yellowtail damselfish, Microspathodon chrysurus FRIEDMAN, ST*; ROCHA, LA; University of Washington; California Academy of Sciences Sarahsea@prodigy.net
Globally, there are numerous biogeographic barriers that physically restrict the dispersal and distributions of marine ichthyofauna. These barriers range from obtrusive land masses, such as the Isthmus of Panama to large spatial separations like the Eastern Pacific Barrier. Regardless of the method of separation, these biogeographic obstacles are known to correlate with speciation events. One of the more geologically recent barriers is the massive outflow of freshwater from the Amazon and Orinoco Rivers off the coast of Brazil. In this project, we conduct molecular analysis of two fish: the yellowtail damselfish, Microspathodon chrysurus, which ranges from the Caribbean to Brazil and a sister species, Microspathodon frontatus, which is endemic to the western coast of Africa. While M. chrysurus and M. frontatus are known to be genetically isolated by the vast expanse of the Atlantic Ocean, we hypothesize that the Amazonian outflow has caused a disruption in the gene flow between the Caribbean and Brazilian populations of M. chrysurus, inducing a speciation event. To analyze the separate populations, two mitochondrial genes (Cytochrome Oxidase 1 and Cytochrome b) were sequenced from specimens collected in each locality. Coalescent and population genetic analyses of the sequenced genes were conducted to elucidate discrepancies between the two populations. This study will aid in our understanding of how population divergence manifests at a molecular level and ultimately, how geological processes shape such speciation events.