Density-Dependent Selection during Range Expansion Affects Expansion Load in Life History Traits.

AbstractModels of range expansion have independently explored fitness consequences of life history trait evolution and increased rates of genetic drift-or "allele surfing"-during spatial spread, but no previous model has examined the interactions between these two processes. Here, using spatially explicit simulations, we explore an ecologically complex range expansion scenario that combines density-dependent selection with allele surfing to asses the genetic and fitness consequences of density-dependent selection on the evolution of life history traits. We demonstrate that density-dependent selection on the range edge acts differently depending on the life history trait and can either diminish or enhance allele surfing.

Patterns, Predictors, and Consequences of Dominance in Hybrids.

AbstractCompared to those of their parents, are the traits of first-generation (F) hybrids typically intermediate, biased toward one parent, or mismatched for alternative parental phenotypes? To address this empirical gap, we compiled data from 233 crosses in which traits were measured in a common environment for two parent taxa and their F hybrids. We find that individual traits in Fs are halfway between the parental midpoint and one parental value. Considering pairs of traits together, a hybrid's bivariate phenotype tends to resemble one parent (parent bias) about 50% more than the other, while also exhibiting a similar magnitude of mismatch due to different traits having dominance in conflicting directions.

Gene-environment interplay in Drosophila melanogaster: chronic nutritional deprivation in larval life affects adult fecal output.

Life history consequences of stress in early life are varied and known to have lasting impacts on the fitness of an organism. Gene-environment interactions play a large role in how phenotypic differences are mediated by stressful conditions during development. Here we use natural allelic 'rover/sitter' variants of the foraging (for) gene and chronic early life nutrient deprivation to investigate gene-environment interactions on excretion phenotypes.