Meeting Abstract
A longstanding goal in Evo-Devo is to better understand the role of phenotypic plasticity in evolutionary diversification. The dung beetle Onthophagus taurus exhibits a nutrition-sensitive male dimorphism in which high nutrition results in fully horned fighter males whereas development under low nutrition conditions result in hornless sneaker males. This species was introduced around fifty years ago from the Mediterranean to the US and to Western Australia (WA). Since then, the body size-horn size threshold has diverged rapidly and heritably between these two populations to a degree normally only observed between closely related species. Previous work suggests that threshold divergences evolved in response to vastly different levels of intra- and interspecific competition for breeding opportunities in both exotic ranges. At the same time, separate work failed to find plasticity for the size threshold in descendant WA populations. Here we test the hypothesis that ancestral Mediterranean populations did harbor plasticity in the expression threshold sizes in response to high and low competition levels and that this ancestral plasticity facilitated the subsequent evolution of canalized divergences between populations, resulting in the loss of plasticity in the descendant WA populations. We test this hypothesis by exposing F1 O. taurus reared from a Mediterranean population to high and low population densities, respectively, and test whether competition levels experienced by mothers, father, or both alters the threshold body size expressed by their male offspring. We discuss the implications of our results for our understanding of the role of phenotypic plasticity and genetic accommodation in developmental evolution.
