NISHIGUCHI, M.K:*; JONES, B.W.; New Mexico State University; New Mexico State University: Population dynamics of sepiolid squid-Vibrio mutualism from the Indo-west Pacific

The sepiolid squid-Vibrio mutualism is an excellent system for examining mechanisms of cospeciation and host tracking patterns among a wide variety of symbiotic squid species. Currently, we are using genetic diversity and nested clade analyses to examine the variation between three allopatric Euprymna squid species: Euprymna scolopes (Hawaii), E. hyllebergi (Thailand), and E. tasmanica (Australia). Using the cytochrome c oxidase subunit I locus for host squid species, and the glyceraldehyde phosphate dehydrogenase (gapA) locus for Vibrio symbionts, we have determined the genetic relatedness of these partners in the Indo-west Pacific as well as the phylogeography and fixation indices between populations of both squids and symbionts. Patterns of host specificity are predominant among symbiont genotypes and their phylogeography, but there is also some evidence of strain variation and secondary colonization, which may preclude that squid populations are not the only driving force for selection of symbiont speciation.