Miocene radiation of deep-sea hydrothermal vent shrimp (Caridea: Bresiliidae): evidence from mitochondrial cytochrome oxidase subunit I.

The evolutionary history of deep-sea shrimp (Caridea: Bresiliidae) inhabiting deep-sea hydrothermal vent and hydrocarbon seep environments was assessed using the mitochondrial Cytochrome c Oxidase subunit I (COI) gene (600 bp). Phylogenetic analyses (parsimony, likelihood, and neighbor-joining) recovered three distinct clades (A, Rimicaris/Chorocaris/Opaepele; B, Alvinocaris; and C, Mirocaris) consistent with higher level taxonomy based on morphology. However, robust phylogenetic results suggested that Chorocaris is paraphyletic and that Mirocaris fortunata and M. keldyshi may not be genetically distinct. A Kishino-Hasegawa likelihood approach was used to test alternative phylogenetic hypotheses based on biogeography and morphology. Evolutionary relationships of vent-endemic shrimp species did not appear to be correlated either with their extant biogeographic distribution or with the history of sea floor spreading. Additionally, COI data suggested that these vent-endemic organisms are not remnants of a Mesozoic vent assemblage; instead, they radiated in the Miocene. Copyright 1999 Academic Press.