Genotype-by-Environment Interactions for Seedling Establishment Across Native and Degraded-Forest Habitats in a Long-Lived Cycad

Abstract

Habitat differences might promote adaptive differentiation among populations that can be evidenced by genotype-by-environment interactions (GxE). I examined GxE in seed germination and seedling survival in demes of a rainforest cycad across their native and degraded-forest habitats, and explored the role of maternal effects and resource availability on the observed GxE. A reciprocal-transplant experiment showed a home-site advantage in terms of establishmen of the demes. Germination in a manipulative greenhouse experiment mirrored the patterns in natural environments, with GxE in response to light and water availability. Overall germination was lower in the degraded-forest habitat and under high-light and low-water conditions in the greenhouse. Several analysis suggested that maternal effects related to size on germination are weak, but maternal effects are suggested by better survival of larger seedlings in the degraded-forest habitat. With weak maternal effects, GxE in establishment of individuals suggest some adaptive differentiation across demes in this cycad, which could have implications for population persistence in its habitats.