Abstract
For wide array of traits such as flower display, nectar production rates, sex allocation, sex ratio and defence systems, the structuring of populations at small scales is fundamental for evolutionary dynamics and the maintenance of genetic diversity. As an example we want to study selection on nectar production rate (NPR) in experimental and natural populations of Echium vulgare with different spatial arrangements. Molecular markers will be used to estimate changes in gene freqencies in these populations. We hypothesise for a population in a patchy environment, that within patches there is no individual advantage (in terms of pollinator service) for plants with high NPR and that plants with high NPR do increase the average number of approaches to al! plants in a patch. Because plants with low NPR do not have the costs of high nectar production they will have a fitness advantage within patches. Compared to pants with low NPR, individuals with high NPR will occur on average in patches that offer a larger reward to pollinators. On the total population level, plants with high NPR may therefore have a fitness advantage. This advantage will diminish with increasing frequencies of genotypes with high rewards. In turn such frequency dependent selection will I lead to polymorphic evolutionary stable strategies an may thus help to explain the maintenance of the large genetic variation in nectar production we found for E. vulgare. Despite its importance, we know as yet very little about how distribution patterns and evolutionary processes interact in the field. Our project will! be among the first to study such an interaction for plant populations.
Netherlands