Long-term Sabbatical

Chiton phylogeny and comparative phylogeography

PI(s): Douglas Eernisse (California State University-Fullerton)
Start Date: 1-Sep-2006
End Date: 31-May-2007
Keywords: biodiversity, phylogenetics, comparative methods

Chitons are basal marine mollusks with conservative morphology. As such they are important model animals for the study of molluscan evolution and marine animals in general. I propose to expand and synthesize ongoing research on worldwide chiton phylogeny and comparative phylogeography. I will focus on the diverse northern Pacific fauna, especially extending current collaborations with Ryan Kelly. We have already extracted and sequenced gene regions from over 1,800 chitons, representing 90 species and 90 percent of those present in the northeastern Pacific (or 10 percent of worldwide chitons). We propose to further analyze these mitochondrial and nuclear sequences, inferring genealogies within separate northern Pacific chiton clades. Building on recent global studies of chitons, we now have compelling evidence that about 10 northeastern Pacific chiton lineages have each radiated within the northern Pacific, together achieving the greatest disparity of morphology, ecology, and size known anywhere for chitons. Living and fossil chiton evidence suggests these radiations occurred surprisingly recently during Pleistocene climatic fluctuations, accompanied by shifting distributions but without obvious long-lasting blocks to gene flow. Our thorough comparative phylogeographic sampling provides us with tremendous potential for a model case of understanding oceanic speciation and diversification processes. I propose to also build on ongoing combined phylogenetic studies of worldwide chiton morphology and DNA, including ongoing international collaborations. This will improve our resolution of the origin and subsequent dispersal events from the northeastern Pacific "hotspot" of chiton diversity, including its historical relationship to Panamic, northwestern Pacific, Arctic, and northern Atlantic chiton faunas through time.

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