Evolution and phylogeography of New World gastropod faunas.

摘要

This dissertation covers a broad range of evolutionary topics, but its primary focus is on the use of molecular phylogenetics to reconstruct phyletic relationships and biogeography of gastropod molluscs, and in particular, the clade Patellogastropoda. The first chapter tests the long held view that the Gulf of California, Mexico is an isolated basin and as such behaves as an island having insular effects on gastropod evolution. Tests are performed that compare the level of endemicity in the Gulf to the surrounding eastern Pacific fauna. The remaining four chapters apply molecular phylogenetics to specific biological methodologies and questions. Chapter 2 examines the combinability of 16S and COI mitochondrial genes in a phylogenetics analysis of New World Patellogastropoda and presents a robust phylogenetic hypothesis. In chapter 3 molecular and morphological techniques are used to resolve a putative cryptic species complex, while in chapter 4, the patellogastropod phylogeny is used in conjunction with an innovative collecting methodology to clarify a long-standing confusion surrounding the identity of several northeast Pacific patellogastropods. This includes the discovery of a new species in the Gulf of California. Lastly, chapter 5 uses a molecular phylogeny to examine the biogeography of the New World patellogastropods and generates testable biogeographical hypotheses for the northeast Pacific, Chilean, and tropical New World faunas. These hypotheses are unified by a global hypothesis that ties the evolutionary history of these patellogastropod faunas to a western Tethyan origin.