Format: ORAL

Iris Reinula1*, Sabrina Trger2,3, Tsipe Aavik1

1 Institute of Ecology and Earth Sciences, University of Tartu, Estonia 2 Institute of Biology/Geobotany and Botanical Garden, Martin-Luther-University Halle-Wittenberg, Germany 3 German Centre for Integrative Biodiversity Research (iDiv), Germany

Over the past century, changes in land use have significantly reduced the extent of semi-natural grasslands, threatening the functional connectivity, i.e., exchange of genes through pollen and seed dispersal, among populations of plants characteristic of these valuable habitats. Although growing evidence suggests that landscape features can influence gene flow among isolated plant populations, the role of historical land use legacies in shaping the relationship between current landscape characteristics and gene flow in perennial grassland plants remains unclear. Notably, studies often focus solely on genetic diversity at neutral loci (not under natural selection), overlooking genetic diversity at adaptive loci (under natural selection) crucial for plant adaptability to changing conditions. We studied the impact of landscape characteristics on the functional connectivity of 32 populations of the grassland plant Primula veris in two historically semi-natural grassland-dominated landscapes in Western Estonia. Nowadays, one landscape remains grassland-dominated, while forests and agricultural fields prevail in the other. We examined genetic diversity at both neutral and adaptive loci and structure of these populations. We also assessed the role of landscape characteristics on gene flow at neutral loci. The relative permeability of different landscape elements for gene exchange depended on landscape context, likely reflecting opposite land use trajectories in these landscapes. Furthermore, the outcome was also affected by different gene flow indices, indicating their context-dependency. Notably, genetic diversity at neutral and adaptive loci showed different results to landscape context. Conclusively, applying connectivity measures based on findings from a landscape setting reflecting only one type of land use trajectory should be avoided. Interpretation of gene flow measures for long-lived plant species should also be approached with caution due to potential delays in their response to landscape changes. Lastly, the correlation between genetic diversity at neutral and adaptive loci is not consistent, warning against using one to estimate the other.