Poeciliids (Pisces, Poeciliidae), the guppies, swordtails, and mollies, are a family of small fishes that are frequently used as a model system in many biological studies. Research topics range from zoogeography, cancer, mating systems, natural and sexual selection, comparative ecology, to conservation biology. Despite their widespread use, very little is known about the phylogenetic or genealogical relationships of poeciliids. The aim of this project by Dr. Axel Meyer at SUNY-Stonybrook is to establish such a phylogeny for the poeciliids using mitochondrial and nuclear DNA sequence data as measures of mutational differences between species. The complete sequence of the mitochondrial gene cytochrome b (about 1100 base pairs) and partial sequences of a nuclear gene, the proto-oncogene X-src (about 520 base pairs), will be obtained from several representatives of the species and genera in this family. The use of both mitochondrial and nuclear sequence data permits the inference of phylogenetic relationship across broad taxonomic levels, from species to family, and also provides independent checking of the resulting phylogenetic estimates. These estimates will then permit testing of vicariance models of biogeography and other aspects of evolutionary diversification in this group of fishes.
