Data from: 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 estimated general combining ability (GCA),
specific combining ability (SCA), reciprocal effects (RGCA and RSCA), and
their interactions with water availability. We examined norms of reaction
for maternal and paternal families and for each maternal/paternal pair to
reveal the magnitude of genetic variation in phenotypic plasticity for
seed size in each population. Results: Seed size in the sampled
populations of D. californica is determined primarily by the combination
of watering treatment, GCA and RGCA; parental identity alone does not
consistently affect seed size. Across genotypes, water availability did
not have a significant effect on seed size. Conclusion: Genetic variation
in phenotypic plasticity of seed size is greater than variation among
genotypes.