On 17 June at 10:15 Iris Reinula will defend her doctoral thesis "Genetic variation of grassland plants in changing landscapes" for obtaining the degree of Doctor of Philosophy (in Botany and Mycology).
Supervisor: Associate Professor Tsipe Aavik
Opponent: Dr. Walter Durka, Helmholtz Centre for Environmental Research (Germany)
Recent land use changes have transformed natural ecosystems, leading to the fragmentation of natural and semi-natural habitats. Many semi-natural grasslands are overgrown or turned into intensively managed agricultural land, significantly altering habitat conditions for grassland plants. Not all organisms can adapt to these changes, resulting in biodiversity loss, including genetic diversity – the diversity within species or populations. As genetic diversity ensures the organisms’ ability to adapt to changes, it is vital to protect and preserve it. This thesis aimed to study the effect of landscape structure and land use change on the genetic diversity of insect-pollinated grassland plants using Trifolium montanum and Primula veris as study species. We found that a higher proportion of grasslands in the surroundings of the study populations, particularly those with higher edge density, support the genetic diversity of grassland plants. Forest, however, had a variable effect on genetic diversity. We also studied how the landscape between plant populations affects the gene flow (exchange of genetic information through pollen or seed flow) between plant populations. The commonly expected pattern of populations geographically further apart being also more different genetically held true only in some situations. A higher historical proportion of grasslands between study populations facilitated gene flow. A comparison of genetic diversity in open and overgrown grasslands revealed higher genetic diversity assessed at putatively adaptive loci in overgrown habitats, whereas neutral genetic diversity remained unaffected by the overgrowth. This indicates to the process of plant populations adapting to the new environmental conditions. Overall, I found that while overgrowth affects the genetic diversity of grassland plants and heterogeneous grassland is desirable, scales, delayed responses, and land use history must be considered when planning conservation activities.
