Human management increases genetic differentiation and weakens isolation by distance across stingless bees

Background/Question/Methods

Pollination services provided by wild bees are increasingly threatened by the loss and modification of natural habitats, posing a risk to the maintenance of native plant biodiversity and agricultural production. Stingless bees (Apidae: Meliponini), key native pollinators across the tropics, have proven particularly susceptible to the degradation of natural habitats. Although dispersal is thought to be restricted in this group of bees, potentially hindering their ability to re-locate to high-quality habitats, the impact of land use on stingless bee gene flow remains unknown. We aimed to fill this knowledge gap by analyzing isolation by geographic distance and landscape resistance across 18 stingless bee species, using microsatellite-based data on population differentiation. 

Results/Conclusions

We found evidence of a significant isolation by distance (IBD) across the entire group of species, although the magnitude of the relationship between genetic and geographic distance varied between species. Species represented by managed colonies were on average more genetically differentiated and showed weaker IBD than species represented by wild colonies. Isolation by resistance (IBR) also showed large inter-specific variation, and further revealed that elevation, precipitation, and temperature resistance were generally positively associated with genetic differentiation. These effects were weak, suggesting that stingless bee dispersal is not as restricted as previously thought, although additional factors not considered in this study might be influencing IBR. Overall, our work reveals that stingless bee species exhibit substantial variation in gene flow and suggests that human management is influencing large-scale dispersal patterns in many species. Our work thus provides new important insights and guidelines to safeguard stingless bees in changing tropical agro-ecosystems.