Abstract
The maintenance of genetic variation is crucial at the margins of a species' distribution range where plants grow in a suboptimal environment and often put less effort into sexual recruitment. The main focus of this study was on exploring the variation in genetic patterns and plant fitness of the long-lived clonal legume Trifolium alpestre in marginal populations in comparison to the distribution centre with the purpose to plan adequate conservation actions for this species.
We used highly variable microsatellite loci to explore genetic patterns in 16 populations of varied size in Trifolium alpestre at the different parts of its range (marginal/central populations in Estonia, Poland and Czechia) of this species. We also studied overall genetic structure and population divergence, and historical and contemporary gene flow within each region.
To estimate the potential for sexual reproduction at the marginal and central area, we measured the amount and weight of seeds produced in Estonian and Czech populations. Our study revealed high H-E and A(R) in all studied populations that were unconnected with population size, and the occurrence of unique alleles both in central as well as in marginal northernmost (Estonian) populations.
Overall genetic structure reflected the geographical location of populations. Very weak population structure together with high historical migration at the distribution margin imply a past, more continuous occurrence of T. alpestre in the northernmost region.
Recent bottlenecks, lowered seed production and lighter seeds in marginal populations point to the local suboptimal conditions and indicate the need to pay more attention to management to prevent loss of genotypes and maintain diverse populations in this region.