EVOLUTIONARY PERSPECTIVES IN A MUTUALISM OF SEPIOLID SQUID AND BIOLUMINESCENT BACTERIA: COMBINED USAGE OF MICROBIAL EXPERIMENTAL EVOLUTION AND TEMPORAL POPULATION GENETICS
Version of Record online: 12 JAN 2012
© 2012 The Author(s). Evolution© 2012 The Society for the Study of Evolution.
Volume 66, Issue 5, pages 1308–1321, May 2012
How to Cite
Soto, W., Punke, E. B. and Nishiguchi, M. K. (2012), EVOLUTIONARY PERSPECTIVES IN A MUTUALISM OF SEPIOLID SQUID AND BIOLUMINESCENT BACTERIA: COMBINED USAGE OF MICROBIAL EXPERIMENTAL EVOLUTION AND TEMPORAL POPULATION GENETICS. Evolution, 66: 1308–1321. doi: 10.1111/j.1558-5646.2011.01547.x
- Issue online: 20 APR 2012
- Version of Record online: 12 JAN 2012
- Accepted manuscript online: 22 DEC 2011 05:16AM EST
- Received April 19, 2011, Accepted October 25, 2011
- experimental evolution;
- sepiolid squid;
The symbiosis between marine bioluminescent Vibrio bacteria and the sepiolid squid Euprymna is a model for studying animal–bacterial Interactions. Vibrio symbionts native to particular Euprymna species are competitively dominant, capable of outcompeting foreign Vibrio strains from other Euprymna host species. Despite competitive dominance, secondary colonization events by invading nonnative Vibrio fischeri have occurred. Competitive dominance can be offset through superior nonnative numbers and advantage of early start host colonization by nonnatives, granting nonnative vibrios an opportunity to establish beachheads in foreign Euprymna hosts. Here, we show that nonnative V. fischeri are capable of rapid adaptation to novel sepiolid squid hosts by serially passaging V. fischeri JRM200 (native to Hawaiian Euprymna scolopes) lines through the novel Australian squid host E. tasmanica for 500 generations. These experiments were complemented by a temporal population genetics survey of V. fischeri, collected from E. tasmanica over a decade, which provided a perspective from the natural history of V. fischeri evolution over 15,000–20,000 generations in E. tasmanica. No symbiont anagenic evolution within squids was observed, as competitive dominance does not purge V. fischeri genetic diversity through time. Instead, abiotic factors affecting abundance of V. fischeri variants in the planktonic phase sustain temporal symbiont diversity, a property itself of ecological constraints imposed by V. fischeri host adaptation.