Mechanisms of reproductive isolation are a central topic of evolutionary research because they determine the frequency of genetic exchange between populations and ultimately contribute to the origin of new species. The genetic basis of reproductive isolation in plants is poorly understood. We propose to study mechanisms of reproductive isolation by investigating the genetic parameters controlling success or failure of reproduction itself. We hypothesize that evolutionary divergence of reproductive processes after ecological and geographic separation leads to reduced reproductive success and gene flow between populations or closely related species. Therefore, reproductive divergence constitutes an important step in speciation. We will concentrate on components that act post-mating, but pre- and immediately post-zygotic, such as genes controlling the formation and number of gametophytes, their communication with each other preceding fertilization, and factors governing fertilization success. Starting from established knowledge about the underlying developmental processes and evolutionary genomics, we will identify and investigate the function of candidate genes controlling reproduction, ask how evolution has shaped gene products and their interplay, and study the fitness effects of gene variants in different ecological and genetic backgrounds. We here present a European collaborative and cross-disciplinary proposal to analyse the genetic and molecular basis of plant reproductive barriers in a systematic and rigorous fashion, using state-of-the-art tools of ecological and evolutionary functional genomics.
