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) inhabiti ng deep-sea hydrothermal vent and hydrocarbon seep environments was assesse d using the mitochondrial Cytochrome c Oxidase subunit I (COL) gene (600 bp ). Phylogenetic analyses (parsimony, likelihood, and neighbor-joining) reco vered three distinct clades (A, Rimicaris/Chorocaris/Opaepele; B, Alvinocar is; and C, Mirocaris) consistent with higher level taxonomy based on morpho logy. However, robust phylogenetic results suggested that Chorocaris is par aphyletic and that Mirocaris fortunata and M. keldyshi may not be genetical ly distinct. A Kishino-Hasegawa likelihood approach was used to test altern ative phylogenetic hypotheses based on biogeography and morphology. Evoluti onary relationships of vent-endemic shrimp species did not appear to be cor related either with their extant biogeographic distribution or with the his tory of sea floor spreading. Additionally, COI data suggested that these ve nt-endemic organisms are not remnants of a Mesozoic vent assemblage; instea d, they radiated in the Miocene. (C) 1999 Academic Press.