Assessing drivers of dispersal for bees in fragmented landscapes

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Melissa Hernandez and Sevan Suni, Biology, University of San Francisco, San Francisco, CA

Background/Question/Methods
Bees are important pollinators of agricultural crops and wild plants, and there is increasing concern over population declines across species. A proposed driver of decline is habitat fragmentation, which can alter the abundance and distribution of necessary resources and reduce population connectivity. Population persistence in fragmented landscapes depends on dispersal, which maintains genetic diversity within populations. We explored if interspecific variation in bee body size is associated with levels of dispersal across a fragmented landscape in southern Costa Rica. Using ddRADseq, we characterized levels of gene flow and genetic diversity for ten Euglossine bee species that vary in body size from 9 mm to 28 mm.
Results/Conclusions
There was variation among species in their levels of dispersal among and genetic diversity within forest fragments. There was no evidence of restricted gene flow for the most highly abundant species in our dataset, Euglossa championi, which also showed high genetic variability within populations. We discuss the roles that body size and landscape play in determining levels of dispersal for Euglossine bees, as well as the usefulness of measures of body size for predicting vulnerability or resilience of bees living in fragmented landscapes.