Edge effects enhance selfing and seed harvesting efforts in the insect-pollinated Neotropical tree Copaifera langsdorffii (Fabaceae)

Edge effects may affect the mating system of tropical tree species and reduce the genetic diversity and variance effective size of collected seeds at the boundaries of forest fragments because of a reduction in the density of reproductive trees, neighbour size and changes in the behaviour of pollinators. Here, edge effects on the genetic diversity, mating system and pollen pool of the insect-pollinated Neotropical tree Copaifera langsdorffii were investigated using eight microsatellite loci. Open-pollinated seeds were collected from 17 seed trees within continuous savannah woodland (SW) and were compared with seeds from 11 seed trees at the edge of the savannah remnant. Seeds collected from the SW had significantly higher heterozygosity levels (H-o = 0.780; H-e = 0.831) than seeds from the edge (H-o = 0.702; H-e = 0.800). The multilocus outcrossing rate was significantly higher in the SW (t(m) = 0.859) than in the edge (t(m) = 0.759). Pollen pool differentiation was significant, however, it did not differ between the SW (Phi(ft)'' = 0.105) and the edge (Phi(ft)'' = 0.135). The variance effective size within the progenies was significantly higher in the SW (N-e = 2.65) than at the edge (N-e = 2.30). The number of seed trees to retain the reference variance effective size of 500 was 189 at the SW and 217 at the edge. Therefore, it is preferable that seed harvesting for conservation and environmental restoration strategies be conducted in the SW, where genetic diversity and variance effective size within progenies are higher.