LAUSR

Abstract It is still a matter of debate how reproductive and genetic characteristics of range-edge populations differ from those central to its range, yet this is important for future changes in species’ ranges. Here we use microsatellite markers to assess the genetic diversity, relatedness and clonal reproduction of two lime tree species, Tilia cordata and T. platyphyllos, from leading range-edge and central locations. Clonal reproduction was limited in the populations studied, but leading range-edge populations contained more clones than populations sampled from lower latitudes. Although no inbreeding or lower genetic diversity was detected, leading range-edge populations have a higher average relatedness of individuals and a lower effective population size than those populations closer to the centre of the species’ distribution. Trees further apart than 26 m are unlikely to be clones and those further apart than 61 m are not likely to be closely related. The implications for forest managers are that although leading range-edge populations have a lower effective population size, they are also likely to be better adapted to northern climes. Because locally sourced trees appear to have sufficient genetic diversity and predominantly result from sexual reproduction they are likely to adapt to climate change and be suited for natural migration and a good source for assisted migration. This is a promising prospect for the potential of future natural or managed expansion and increased species abundance.