BEGOVIC, E.: Feeding Specialization and Diversification Patterns of Eastern Pacific Patellogastropoda

To investigate the role that feeding specialization may play in clade diversification and mode of speciation, I have begun preliminary phylogenetic and sterol analyses of eastern Pacific Patellogastropoda. A phylogenetic hypothesis for eastern Pacific Patellogastropoda is constructed using mtDNA sequences from the large ribosomal subunit (16s). This phylogeny identifies two putative new species that have sympatric distributions with their respective sister taxa. Both of these taxa share common resources and similar ecotypic forms with their closest sister taxa, indicating that resource partitioning may not have played a significant role in their diversification. This phylogeny also confirms that L.austrodigitalis (Murphy, 1978) is the sibling species of L.digitalis, two species with parapatric distributions overlapping in central California and similar ecotypic forms. This pattern is consistent with the hypothesis that these species diversified as a result of vicariance. Finally, 16s data indicate that L.instabilis and L.ochracea are two distinct ecological forms of the same species. A re-evaluation of the systematics of patellogastropod species is needed. Preliminary analyses have been used to identify biogenic sterols in a subset of lottid taxa. Sterols incorporated into shell and body tissues can be used to identify diet in recent and fossil gastropods. These sterols can be used to determine past ecologies of fossil patellogastropods, whether resource partitioning exists at finer levels, if resource partitioning has changed through time within lineages, and to identify specialist versus generalist forms. Mapping these data onto a phylogenetic tree will allow me to examine the evolutionary history of feeding and resource partitioning of patellogastropods, which may shed light on the role of feeding specialization in clade diversification.