Host: Brian Sedio
Title: Gene by environment interactions, genetic variation, and the evolution of plasticity within and across generations
Abstract:
The phenotypes of organisms result from the combined influence of their genes, their environments, and interactions between the two. Genotype by environment interactions (G×E) occur when genotypes respond differently to environmental variation, they are widespread and fuel both local adaptation and phenotypic plasticity. Maternal effects can also interact with environments, which allows for transgenerational plasticity. I used single-locus population genetic models to compare the evolution of transgenerational and intragenerational plasticity. I found that transgenerational plasticity should evolve at half the rate of intragenerational plasticity. These models assume the presence of relevant genetic variation. Next, I tested this assumption using a two-generation experiment using Arabidopsis thaliana in which the parental generation was grown either with or without competition, in ambient or elevated CO2, while their offspring were grown in a common environment. I found genetic variation for transgenerational plasticity in response to CO2 and competition on germination and fruit counts. This genetic variation may provide additional avenues for adaptive evolution in response to global change. Finally, organisms can modify their environments and that of others. I assessed the fitness effects and interactions between offspring and parental environmental modifications using two populations of dung beetles. Environmental modifications enhanced size, mass, and survival. Furthermore, the two populations have diverged in their reliance on environmental modifications: modifications by offspring appear to buffer against lower maternal investment only in one of the two beetle populations. These differences may be the result of adaptation to diverging novel conditions. For my postdoctoral research with Dr. Sedio, I will investigate why some tropical tree genera are much more speciose than others. A classical hypothesis suggests that evolutionary innovations in chemical defense allows plants to escape their enemies—herbivores and pathogens—resulting in increased diversification relative to sister lineages. Using a combination of transcriptomics, phylogenomics, and metabolomics, I plan to test whether whole genome duplications and gene-family expansions of defensive genes in fact accompany increased diversity.