Covariance among premating, post-copulatory and viability fitness components in Drosophila melanogaster and their influence on paternity measurement.

In polyandrous mating systems, male fitness depends on success in premating, post-copulatory and offspring viability episodes of selection. We tracked male success across all of these episodes simultaneously, using transgenic Drosophila melanogaster with ubiquitously expressed green fluorescent protein (i.e. GFP) in a series of competitive and noncompetitive matings. This approach permitted us to track paternity-specific viability over all life stages and to distinguish true competitive fertilization success from differential early offspring viability. Relationships between episodes of selection were generally not present when paternity was measured in eggs; however, positive correlations between sperm competitive success and offspring viability became significant when paternity was measured in adult offspring. Additionally, we found a significant male × female interaction on hatching success and a lack of repeatability of offspring viability across a focal male's matings, which may underlay the limited number of correlations found between episodes of selection.

Adaptive divergence within and between ecotypes of the terrestrial garter snake, Thamnophis elegans, assessed with F(ST)-Q(ST) comparisons.

Populations of the terrestrial garter snake (Thamnophis elegans) around Eagle Lake in California exhibit dramatic ecotypic differentiation in life history, colouration and morphology across distances as small as a few kilometres. We assayed the role of selection in ecotypic differentiation in T. elegans using F(ST)-Q(ST) analysis and identified selective agents using direct and indirect observations. We extended the conventional implementation of the F(ST)-Q(ST) approach by using three-level analyses of genetic and phenotypic variance to assess the role of selection in differentiating populations both within and between ecotypes. These results suggest that selection has driven differentiation between as well as within ecotypes, and in the presence of moderate to high gene flow. Our findings are discussed in the context of previous correlational selection analyses which revealed stabilizing and correlational selection for some of the traits examined.