Meeting Abstract
Species invasions provide an opportunity to study how traits evolve as organisms move into novel environments. The invasion process might act as a filter either via nonrandom dispersal and/or selection, thereby leading to phenotypic differences between the invading and source populations. Here we test the hypothesis that behavior and cognition facilitate the invasion process by comparing natural variation in behavior among genetically-differentiated populations of threespined stickleback that were reared in a common garden. Specifically, we compared sticklebacks from two populations from the ancestral source marine environment to sticklebacks from four freshwater lakes that differ in time since establishment. If increased neophilia and inhibitory control are beneficial for colonizing new environments, and thus evolve over the course of a biological invasion, then we predicted that derived freshwater populations would be more neophilic and exhibit higher levels of inhibitory control (i.e. more likely to abandon a behavior pattern that is no longer effective) compared to sticklebacks from the ancestral source population. We observed substantial variation in both traits among populations, and found support for our hypothesis: well-established freshwater populations were more neophilic and had higher inhibitory control than marine fish. Differences between very recently derived freshwater populations suggest that these differences can evolve rapidly, though nonrandom dispersal cannot be excluded as a potential explanation. These findings are consistent with the hypothesis that cognitive traits have played an important role in allowing stickleback to successfully colonize freshwater habitats, and that these traits have evolved during the invasion process.
