Assessing spatial mating patterns in translocated populations of Campanula glomerata

Plant translocations represent a solution for rescuing nonviable populations and recreating population networks. An essential criterion for translocation success is genetic diversity enhancement or maintenance in post-translocation generations. Genetic mixing, i.e. individual relatedness and spatial structure, also needs to be considered. We investigated the processes involved in the spatial patterns of genetic diversity in the first post-translocation generation (recruits and seed progeny) of translocated populations of the insect-pollinated, self-incompatible herb Campanula glomerata. We combined direct and indirect estimates of contemporary mating and gene dispersal using 15 microsatellite loci to estimate clonal extent, and genetic diversity and structure, to reconstruct sibship and parentage and to estimate pollen and seed dispersal distances. Genetic diversity in the first post-translocation generation is representative of the natural seed-source populations. Combining sources enhanced the effective number of breeders (Ne = 102–175). Clonal propagation was only marginal. Pollen and seed dispersal occurred at short distances within populations (up to 18 m), favouring fine-scale spatial genetic structure (SGS). This means that the enhanced genetic diversity, random mating and high admixture levels are ascribed to the mixed spatial arrangement of transplants. Stronger SGS might lead to biparental inbreeding and reduced seed set due to a lack of compatible neighbours, and impact the long-term population genetic sustainability. Increasing seed-dispersal distances within and among sites might be mediated by grazing livestock used for grassland management. Some long-distance pollen flow events (0.68–2.35 km) between populations were also detected, suggesting the potential of creating large translocated populations to restore connectivity by gene flow. •Genetic diversity in post-translocation offspring reflects natural populations.•Admixture and random mating can be ascribed to the mixed spatial planting design.•Parentage and paternity analyses revealed short seed and pollen dispersal distances.•Parentage and paternity analyses detected pollen flow between populations.•Translocating large populations can contribute to restore connectivity.