Meeting Abstract
Sepiolid squids (Cephalopoda: Sepiolidae) are found in mutualistic partnerships with members of the Vibrionaceae throughout the world. Beneficial microbes that are environmentally transferred between generations of their hosts are exposed to abiotic factors that can eventually influence their symbiotic competence. Therefore, we examined the influence of temperature adaptation on the free-living stage of Vibrio fischeri from various hosts and their native temperature regimes. Using in vitro experimental evolution, we adapted five strains of symbiotic V. fischeri from temperate, tropical, and semi- temperate native ranges. These strains were adapted to five temperatures for 2000 generations to assess the impact of temperature adaptation on symbiotic fitness. Physiological assays of growth, luminescence, biofilm activity, and motility were performed comparing evolved V. fischeri lines to their ancestor. Colonization experiments using naïve juvenile squid were performed singly and in competition with their ancestors. Lines evolved at elevated temperature lost their ability to luminesce, especially those from temperate ranges, however, this did not seem to influence colonization efficiency. Evolved lines, regardless of physiological response, gained fitness compared to their ancestors when colonizing a host after 1000 generations while, in some cases, lost this advantage after 2000 generations. Our results indicate that evolved V. fischeri are able to compensate for their altered physiology, influencing colonization fitness. These findings will help determine whether changes in environmental conditions such as temperature will be detrimental to the establishment of symbiotic associations, and therefore have a much greater impact on beneficial microbes that contribute to the overall health of metazoan life.
