Meeting Abstract

51.2  Jan. 6  Microbial Experimental Evolution in the Bobtail Squid-Vibrio Model System SOTO, W.*; NISHIGUCHI, M.K.; New Mexico State Univ., Las Cruces; New Mexico State Univ., Las Cruces wisoto@nmsu.edu

The mutualism between sepiolid squids (Cephalopoda: Sepiolidae) and their bioluminescent symbionts (Genus Vibrio) has become an experimentally tractable system for physiological, evolutionary, molecular, and ecological studies of symbiotic relationships. Since the squid host and their symbionts can be grown and maintained independently of each other in the laboratory, this association is feasible to empirical manipulation, including studies examining differences between closely related host-symbiont pairs. Previous research has shown that native strains of Vibrio fischeri will out-compete non-native ones isolated from different host species when competitive colonization experiments are conducted in the indigenous host. Since previous experimental evolution studies with microorganisms have revealed that adaptation can be observed relatively quickly, we propose a direct approach using experimental evolution to identify symbiotic and ecological loci by evolving non-native V. fischeri through a foreign Euprymna species for 500-750 generations. Since a �frozen fossil record� of symbionts can be generated, the evolving non-native clone has been monitored every 50-100 generations to determine if its competitive ability has improved relative to native strains of V. fischeri. In addition, the relative competitive ability of the derived non-native strain has been compared to the ancestral one to determine if fitness has improved through adaptation. This research addresses the potential of V. fischeri populations to expand into novel host ranges and whether non-native bacterial populations can displace native ones in a particular geographical area.