Meeting Abstract
The role of plasticity in shaping phenotypic diversification continues to receive considerable attention. One especially debated issue concerns the significance of genetic accommodation in diversification, and the proposed role of ancestrally plastic responses in facilitating or biasing subsequent genetically canalized differentiation among taxa. Here, we investigated the role of ancestral plasticity in facilitating rapid divergence between exotic populations of the Mediterranean dung beetle Onthophagus taurus, introduced ~50 years ago to Western Australia and the Eastern United States. Historically, Western Australian and Eastern US populations have been subject to disparate levels of mate- and resource competition, proposed to have driven rapid heritable divergences in diverse morphological, physiological, and behavioral traits. In this study, we utilized a Spanish population as a proxy for the ancestral Mediterranean population to assess whether preexisting plasticity in response to variation in population density may have mediated these previously documented canalized divergences among descendant exotic populations. We focused on two maternal behavioral, two life history, and two morphological traits. We find that (1) Mediterranean O. taurus exhibit plasticity in response to adult densities for four of the six focal traits; (2) that in two of those, plastic responses match the direction of canalized divergences among natural populations; and (3) that the presence and direction of plasticity appear unrelated to trait type. Our results provide partial support for the hypothesis that evolution by genetic accommodation could have contributed to the very early stages of population differentiation in a subset of traits in O. taurus.
