title: Evolution of the additive genetic variance-covariance matrix under continuous directional selection on a complex behavioural phenotype.
abstract: Given the pace at which human-induced environmental changes occur, a pressing challenge is to determine the speed with which selection can drive evolutionary change. A key determinant of adaptive response to multivariate phenotypic selection is the additive genetic variance-covariance matrix ( G: ). Yet knowledge of G: in a population experiencing new or altered selection is not sufficient to predict selection response because G: itself evolves in ways that are poorly understood. We experimentally evaluated changes in G: when closely related behavioural traits experience continuous directional selection. We applied the genetic covariance tensor approach to a large dataset (n = 17 328 individuals) from a replicated, 31-generation artificial selection experiment that bred mice for voluntary wheel running on days 5 and 6 of a 6-day test. Selection on this subset of G: induced proportional changes across the matrix for all 6 days of running behaviour within the first four generations. The changes in G: induced by selection resulted in a fourfold slower-than-predicted rate of response to selection. Thus, selection exacerbated constraints within G: and limited future adaptive response, a phenomenon that could have profound consequences for populations facing rapid environmental change.
authors.affiliation: Canada Research Chair in Functional Ecology, Department of Biology, University of Ottawa, Ottawa, Ontario, Canada vcareau@uottawa.ca.
authors.forename: Vincent
authors.initials: V
authors.lastname: Careau
authors.affiliation: School of Biological Sciences, University of Aberdeen, Aberdeen, UK.
authors.forename: Matthew E
authors.initials: ME
authors.lastname: Wolak
authors.affiliation: School of Biological Sciences, Washington State University, Pullman, WA, USA.
authors.forename: Patrick A
authors.initials: PA
authors.lastname: Carter
authors.affiliation: Department of Biology, University of California, Riverside, CA, USA.
authors.forename: Theodore
authors.initials: T
authors.lastname: Garland
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001522:Behavior, Animal; D005075:Biological Evolution; D005260:Female; D014644:Genetic Variation; D008297:Male; D051379:Mice / Q000235:genetics / Q000502:physiology*; D008813:Mice, Inbred ICR; D008957:Models, Genetic; D009043:Motor Activity; D012641:Selection, Genetic
keywords: Bulmer effect; G-matrix; experimental evolution; genetic covariance tensor; selection limit; wheel running