Effects of small-scale habitat restoration on genetic diversity and connectivity in bee populations

Background/Question/Methods

Pollination is essential for the health of natural ecosystems and agricultural productivity, with over 75% of crops benefitting from animal pollination. Bee populations are in decline due to a suite of anthropogenic changes including habitat destruction. Habitat destruction is particularly harmful when it results in highly fragmented areas of remaining natural habitat, because it limits dispersal among populations, which is critical for the maintenance of genetic diversity. Past habitat loss can reduce viability of small isolated populations due to inbreeding depression and random fixation of deleterious alleles. In an attempt to promote biodiversity, there have been efforts to restore degraded habitats to a more natural state. We investigated the genetic responses of a wild bee species following small-scale habitat restoration in an intensively managed agricultural area. We assessed the genetic diversity and genetic connectivity of populations of the sweat bee Halictus ligatus in hedgerows of floral enhancements along the margins of large crop fields in Yolo County, CA. To measure genetic diversity and connectivity, we performed double-digest restriction site-associated DNA sequencing (ddRADseq).

Results/Conclusions

We found high levels of genetic polymorphism in the agricultural area after conservation intervention. We discuss how genetic diversity varied over time and with landscape factors. Our results provide insight into the ecological and genetic return on investment of habitat restoration activities in agricultural landscapes.