Data from: Nest suitability, fine-scale population structure and male-mediated dispersal of a solitary ground nesting bee in an urban landscape

Bees are the primary pollinators of flowering plants in almost all
ecosystems. Worldwide declines in bee populations have raised awareness
about the importance of their ecological role in maintaining ecosystem
functioning. The naturally strong philopatric behavior that some bee
species show can be detrimental to population viability through increased
probability of inbreeding. Furthermore, bee populations found in
human-altered landscapes, such as urban areas, can experience lower levels
of gene flow and effective population sizes, increasing potential for
inbreeding depression in wild bee populations. In this study, we
investigated the fine-scale population structure of the solitary bee
Colletes inaequalis in an urbanized landscape. First, we developed a
predictive spatial model to detect suitable nesting habitat for this
ground nesting bee and to inform our field search for nests. We genotyped
18 microsatellites in 548 female individuals collected from nest
aggregations throughout the study area. Genetic relatedness estimates
revealed that genetic similarity among individuals was slightly greater
within nest aggregations than among randomly chosen individuals. However,
genetic structure among nest aggregations was low (Nei’s GST = 0.011).
Reconstruction of parental genotypes revealed greater genetic relatedness
among females than among males within nest aggregations, suggesting
male-mediated dispersal as a potentially important mechanism of population
connectivity and inbreeding avoidance. Size of nesting patch was
positively correlated with effective population size, but not with other
estimators of genetic diversity. We detected a positive trend between
geographic distance and genetic differentiation between nest aggregations.
Our landscape genetic models suggest that increased urbanization is likely
associated with higher levels of inbreeding. Overall, these findings
emphasize the importance of density and distribution of suitable nesting
patches for enhancing bee population abundance and connectivity in human
dominated habitats and highlights the critical contribution of landscape
genetic studies for enhanced conservation and management of native
pollinators.