Meeting Abstract

74.4  Sunday, Jan. 6  Transitions between diverse haplotypes reveal population structure between Mediterranean sepiolids and Vibrio symbionts ZAMBORSKY, DJ*; NISHIGUCHI, MK; New Mexico State University; New Mexico State University zambo@nmsu.edu

Mutualisms between sepiolid squids (Cephalopoda: Sepiolidae) and species of the bacterial family Vibrionaceae exemplify one of the few marine symbioses that exhibit high specificity despite their environmental transmission. Previous work has demonstrated a preference to Vibrio fischeri found in host squids of the genus Euprymna. Despite this specialization observed in allopatric populations, strains of V. fischeri are capable of moving both intra- and interspecifically between different host species. In contrast, associations between sepiolids in the Mediterranean lack this specificity between host-symbiont pairs; Mediterranean sepiolids contain three species of luminous bacteria: V. fischeri, V. logei, and Photobacterium leognathi. Using a population genetic approach to better understand the structure of sympatric Mediterranean sepiolids and their bacterial symbionts, we constructed haplotype networks for both the host squid and bacterial symbiont populations. Sympatrically distributed host squids exhibited distinct haplotypes amongst species, with no sharing of any haplotypes measured. Conversely, Vibrio and Photobacterium symbionts were genetically more similar and shared a number of identical haplotypes that were found in different species of host squids. Shared bacterial haplotypes were also present at two sampling sites in Southern France and Eastern Italy indicating introgression of these genotypes between the two populations. These findings corroborate previous results suggesting that abiotic factors such as temperature and water movement may play a more significant role in the formation of this environmentally transmitted symbiosis.