Integration of genetic and seed fitness data to the conservation of isolated subpopulations of the Mediterranean plant Malcolmia littorea.

Abstract

Plant autoecology and population genetics provide a perspective on the likelihood of natural regeneration, which is critical when designing conservation strategies for endangered species. The threatened coastal plant Malcolmia littorea (Brassicaceae) was sampled across its European distribution and studied for genetic diversity and seed fitness, with the aim of providing information for the conservation of isolated and declining populations. Nine microsatellite markers (five chloroplast and four nuclear) were analysed to assess population genetic diversity and structure and to conduct a spatial analysis using the software DIVA-GIS. Germination percentages and rates were assessed by incubating the seeds under eight constant temperatures (0-27°C). The genetic diversity was found to be similar among subpopulations (chloroplast H=0.04-0.17; nuclear Ho =0.20-0.37), with no correlation between subpopulation diversity and the area of occupancy (AOO). The subpopulations were found to be clustered in three genetic groups, and three of them were identified as conservation priorities due to their unique genetic composition. The germination study revealed a significant influence of the maternal environment and AOO on seed germination, with the smaller subpopulations showing lower germination percentages (P<0.05). These results highlight the importance of obtaining information on isolated subpopulations through different experimental approaches (e.g. seed germination plus population genetics) to enable planning of effective conservation actions. For M.littorea, seed collection for both insitu and ex situ conservation should take into account the local adaptation of the subpopulation and the genetic structure of the species.