A phylogenetic approach to understanding the evolution of hybrid viability loci in Tigriopus californicus

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The copepod Tigriopus californicus is an emerging model system for studies of speciation and resistance to environmental stress. Such work will be greatly improved by a better understanding of the evolutionary relationships among T. californicus populations. The current study will construct an evolutionary tree (phylogeny) of 20 populations using DNA sequence from 12 genes. A number of different methods will be used to determine the best evolutionary tree for the combined dataset, including analyses of the level of agreement among different genes. Results will be used to test the null hypothesis that genes evolved at equal rates, with the expectation that nuclear genes (chromosomal genes inherited from both parents) evolved more slowly than mitochondrial genes (genes on a separate organelle inherited only from the mother). The completed phylogeny will provide an evolutionary framework for future planned studies of how gene conflicts accumulate when isolated populations diverge from each other.DNA sequence data will be deposited in public databases, thereby increasing genomic resources for copepods, one of the most abundant groups of multicellular animals on the planet. Beyond its relevance to copepods, the research will contribute to the broader issue of the rate of evolutionary change in mitochondrial vs. nuclear genes. The work will directly fund research by both graduate and undergraduate students. Funds will also be used to support a new collaboration between the Edmands Lab and the Aquarium of the Pacific aimed at enhancing public understanding of issues involving evolution in marine environments.