Meeting Abstract

S11.3  Wednesday, Jan. 6  Environment, Additive Genetic Variance and Evolvability of Body Shape in Threespine Stickleback (Gasterosteus aculeatus) MCGUIGAN, K*; NISHIMURA, N; CURREY, M; HURWIT, D; CRESKO, WA; Univ. Queensland; Univ. Oregon; Univ. Oregon; Univ. Oregon; Univ. Oregon k.mcguigan1@uq.edu.au

Numerous examples of rapid adaptation of populations to novel habitats have been documented. An unanswered question is to what extent populations in novel environments, to which they are not adapted, express greater genetic variation, facilitating rapid evolution. Environment-specific additive genetic variation violates a major assumption of evolutionary quantitative genetics: that variances are constant over the predictive timeframe. Evidence of environment-dependent additive genetic variation is equivocal, with some studies demonstrating increased and some decreased variation. Although quantitative genetic studies have historically focused on variance in individual traits, it is the genetic basis of the multi-trait phenotypes under selection that determines evolutionary response. We used an evolutionary model organism, the threespine stickleback, to ask whether environment altered the expression of additive genetic variation such that populations in novel environments might evolve more rapidly than predicted from estimates in the ancestral environment. Stickleback are characterized by a remarkable adaptive radiation following colonization of post-glacial freshwater lakes by oceanic fish. Freshwater and oceanic populations differ in many phenotypic aspects, including body shape, which contributes to swimming performance, predator evasion and foraging efficiency. We used a half-sib breeding design to determine whether oceanic stickleback expressed greater additive genetic variation in body shape when reared in fresh versus saline water, and whether these differences could have contributed to the rapid adaptation of marine stickleback to freshwater lakes.