Bees travelling south: climate-induced range shifts and suitable habitat losses in south-eastern neotropics

Aim: Provide an assessment of climate change impacts on a set of wild
pollinators restricted to one of the regions with the greatest diversity
of bees in the world. Also, we aimed to test whether functional groups
responded differently to climate projections.
Location: South-eastern South America (SES). Taxon: Bees
(Hymenoptera: Apidae sensu lato) Methods: We selected 18 species
of bees mostly restricted to the SES region, modelled their distributions
and assessed the possible impacts of near future (2050) climate change in
species richness and shifts in range centroids. Potential impacts related
to different functional groups were evaluated through t-tests.
Results: SES species richness were projected to decrease in the
northernmost regions and increase southward. Most bee species were
predicted to shift their range centroids towards the south-west and south,
while suitable stable areas were found in southern Brazil. We also found
higher proportional losses in suitable areas for eusocial species compared
to solitary ones, while generalists showed slightly lower gains than
specialists. Main conclusions: SES bees are likely to undergo
changes in the near future, with projected losses of species at northern
portions and southward increases. The identified stable areas in southern
Brazil underscore the importance of conservation efforts in the region,
particularly in natural grasslands – an endangered habitat with high bee
diversity. Although our results suggest higher vulnerability for
functional groups traditionally considered more resilient, it is essential
to acknowledge that other factors, including habitat and mutualists
availability, behavioural particularities, phenology and range size, must
be determinants for the vulnerability of species to ongoing climate
change.