Using adaptive traits to consider potential consequences of temporal variation in selection: male guppy colour through time and space

Temporal variation in selection is typically evaluated by estimating and comparing selection coefficients in natural populations. Meta-analyses of these coefficients have yielded important insights, but selection coefficients are limited in several respects, including low statistical power, imperfect fitness surrogates, and uncertainty regarding consequences for trait change. A complementary approach without these limitations is to examine temporal variation in adaptive traits themselves, which is mechanistically easier and more directly relevant to evolutionary consequences. We illustrate this approach by analyzing the colour patterns of male guppies, Poecilia reticulata, from each of six sites in Trinidad in each of 6 years. This system is particularly appropriate for our study because key aspects of colour variation are genetically-based and responsive to selection. However, although spatial patterns of colour variation have been extensively considered in this system, no study has ye...