Genetic diversity and interaction structure of insects and plants

Abstract

This proposal comprises two subprojects. Subproject 1, "Trophic specialization and genetic diversity of phytophagous insects", aims at evaluating how the genetic diversity of herbivorous insects is influenced by their trophic specialization and geographic extent. Microsatellite markers will be used to amplify specific regions of the herbivores' DNA, which will be used to compute measures of genetic diversity and gene flow for the studied populations. We intend to estimate the relative contribution of host plant breadth and geographical distribution in determining the genetic structure of specialist and generalist herbivorous insects. We will also investigate local genetic differentiation of conspecific herbivores that use different host plants. In subproject 2, "Trophic specialization, interaction diversity and community organization", we will construct a general theoretical framework for interaction diversity, formalized as a model of generalized entropy. The unifying concept for this framework is specialization, taken to encompass biotic interactions as well as their spatial differentiation. We will develop specific models to investigate potential determinants of trophic specialization, especially phylogenetic range of host species on their consumers. A further model will serve to evaluate the congruence of geographic turnover (beta diversity) among functionally coupled species assemblages, and the phylogenetic or spatial determinants of this congruence. The effectiveness of a generalized entropy model for interaction diversity and its practical applicability will be assessed with large data sets on plant-herbivore interactions, starting with the data base on phytophagous insects associated with Astraea flower heads, amassed by our research group in preceding studies over several decades. (AU)