PARENT SESSION
Oral Session # 46: Evolutionary Ecology I: Plants.
Presiding: P Minchin
Wednesday, August 6. 8:00 AM to 11:30 AM, SITCC Meeting Room 201.
Genetic constraints on the evolution of dispersal are mediated by phenotypic plasticity.
Wender, Naomi1, Donohue, Kathleen1, 1 Department of Organismic and Evolutionary Biology, Cambridge, MA, 02138
ABSTRACT- We investigated the quantitative genetics of seed dispersal in Arabidopsis thlaiana and found a novel genetic constraint on the evolution of dispersal that is mediated by phenotypic plasticity. We grew several ecotypes of A. thlaiana in high and low density, measured maternal plant characters, and then characterized seed dispersion patterns in a wind tunnel. We identified maternal plant traits that influenced seed dispersion patterns and found significant genetic variation for these maternal traits. The genetic variation for maternal traits that influence seed dispersion patterns, moreover, did not differ with density. However, these plant traits determined dispersal more strongly when plants were grown at high density than when they were grown at low density. In addition, we found significant genetic variation for both dispersal distance and for seed density after dispersal. Genetic variation for seed density after dispersal, however, was only detectable at high density. Therefore, as increased dispersal ability evolves and plants experience lower densities as a result, the expression of genetic variation for dispersal is expected to decline. Thus, a limit to the evolution of dispersal would result. In this study, we therefore detected a novel environment-dependent genetic constraint that is mediated by the evolution of the trait itself.
Key words: phenotypic plasticity, Arabidopsis, dispersal, quantitative genetics