Genotype x environment interaction obscures genetic sources of variation in seed size in Dithyrea californica but provides the opportunity for selection on phenotypic plasticity

Premise: Seed size is a functional trait that influences individual fitness but the genetic basis of
variation in individual seed size in wild species remains still largely unknown. The evolutionary
trajectory of seed size depends, in part, on whether seed size variation is determined by additive,
maternal, or non-additive genetic variance. The expression of these sources of variance in seed
size may be environment-dependent, reflecting genetic variation in phenotypic plasticity. In this
study, we used a quantitative genetic approach to reveal the genetic basis of seed size and its
plastic response to drought stress in Dithyrea californica.
Methods: We used a diallel mating design to estimate genetic and environmental variance
components for seed size in each of three greenhouse-raised populations sampled from
California and northern Mexico. We replicated diallels in two watering treatments to examine
genetic parameters and genotype x environment interactions affecting seed size. We est...