Genetic variation in the response of pollen germination to nutrient availability and elevated atmospheric CO2 concentrations in Epilobium angustifolium

It is expected that global climatic changes could lead to shifts in the genotypic composition of species that exhibit genetic variation in the response of fitness-related traits to an increase of atmospheric CO2. In plants that reproduce sexually, fitness can be described both by a female and a male component. Whereas the existence of genetic variation in the response to elevated CO2 of traits related to female fitness has been the focus of recent studies, studies on the response of the male component of fitness are still missing. Here, we report on the effects of elevated atmospheric CO2 and nutrient availability on che pollen quality of five full-sib families of Epilobium angustifolium. We did not detect an effect of the treatments on the in vitro pollen tube growth. However, we observed significant variation among families for pollen germination probabilities and a significant family x CO2 x nutrient interaction on this trait. This indicates that, in combination with nutrients increased CO2 could exert a selection pressure resulting in changes in the genetic structure of populations and in their mean response to CO2. It seems important that this evolution is included in models simulating the consequences of climate change on plant communities.