Abstract
- Background and AimsSpeciation is often described as a continuous dynamic process, expressed by differentmagnitudes of reproductive isolation (RI) among groups in different levels of divergence. Studying intraspecificpartial RI can shed light on mechanisms underlying processes of population divergence. Intraspecific divergencecan be driven by spatially stochastic accumulation of genetic differences following reduced gene flow, resulting inincreased RI with increased geographical distance, or by local adaptation, resulting in increased RI with environ-mental difference.- Methods We tested for RI as a function of both geographical distance and ecological differentiation inIris atro-purpurea, an endemic Israeli coastal plant. We crossed plants in the Netanya Iris Reserve population with plantsfrom 14 populations across the species’ full distribution, and calculated RI and reproductive success based on fruitset, seed set and fraction of seed viability.- Key ResultsWe found that total RI was not significantly associated with geographical distance, but significantlyincreased with ecological distance. Similarly, reproductive success of the crosses, estimated while controlling forthe dependency of each component on the previous stage, significantly reduced with increased ecological distance.- ConclusionsOur results indicate that the rise of post-pollination reproductive barriers inI. atropurpureais moreaffected by ecological differentiation between populations than by geographical distance, supporting the hypothesisthat ecological differentiation is predominant over isolation by distance and by reduced gene flow in this species.These findings also affect conservation management, such as genetic rescue, in the highly fragmented and endan-geredI. atropurpurea.