Landscape genomics of a grassland plant Primula veris in fragmented alvar grasslands of Estonia

Abstract

Loss and fragmentation of natural and semi-natural habitats is one of the major threats to genetic diversity. Lowered genetic diversity, in turn, may jeopardize the ability of fragmented populations to respond to environmental perturbations, such as climate change and pollution.

Significant advances in molecular tools during recent years have provided researchers with unprecedented insight not only into patterns of neutral genetic diversity of wild populations, but is now allowing to quantify variation at those regions of the genome, which are affected by natural selection, i.e. adaptive genetic variation. Information on genetic diversity of adaptive relevance helps to predict the vulnerability of wild species to ongoing climate change and significantly facilitates organising conservation of populations in environmentally dynamic habitats. Nevertheless, studies applying such high-throughput genomic tools are still rare in conservation biology.

We examined the genomic diversity of 42 populations of Primula veris (20 individuals per population), an insect-pollinated plant species characteristic of calcareous grasslands, in alvar grasslands of Western Estonia. Alvar grasslands are characterised by high plant species richness and unique species composition, but have suffered from severe decrease in area and connectivity during the last hundred years, and hence represent habitats with high conservation importance. These grasslands are thus a good study system for examining the impact of recent landscape change on biodiversity.

To assess genetic diversity of the study populations, we use nearly 5000 single nucleotide polymorphisms (SNPs) obtained through restriction site associated DNA sequencing (RADseq). In addition to current landscape characteristics, we obtained detailed historic information on alvar area and connectivity and surrounding landscape characteristics in 1930s. Furthermore, we have collected a detailed set of various environmental variables at study locations, which help to determine key drivers of local adaptation in our study system. Preliminary evidence indicates that current patterns of genomic diversity in Primula veris may exhibit a delayed response to landscape change. We are convinced that our project, which has been carried out in close collaboration with conservation practitioners, will help to propose effective measures for conservation of fragmented plant populations in the light of environmental changes.