Do the effects of habitat loss and fragmentation on the population genomics of bees and bee-plant-interactions differ across functional traits (diet and body size) in Centris oil-bees of South America?

• Applicant: Dr. Belinda Kahnt
• Subject Area: Ecology and Biodiversity of Animals and Ecosystems, Organismic Interactions ; Evolution, Anthropology
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 501673782

Landscape fragmentation and habitat loss are among the major threats to global bee diversity with negative consequences for pollination service provision and human well-being. However, it is still not well understood if certain functional traits render some bee species more vulnerable to environmental changes than others. It has been suggested that body size and diet breadth are two of the most important ecological traits that influence how bees cope with environmental changes. Body size is linked to the metabolism, longevity, fecundity and migration ability of individuals, while diet breadth is linked to resource usage. Both traits could impact the genetic diversity, intraspecific gene flow and the genetic structure of populations, which in turn reflect the size and connectivity of populations and thus their extinction risk. Generally, specialist and/or small species seem to experience a higher threat risk as their populations tend to be smaller in size (genetically less diverse) and/or less connected (genetically more structured). South American oil-collecting Centris bees are an ideal system to study if the genetic impact of environmental changes is dependent on species specific traits as Centris species differ not only in their dietary specialisation but also body size. I thus propose to use a comparative population genomic approach and whole-genome-sequencing to test if Centris species that vary in their dietary specialisation and body size also differ in their genetic response to fragmentation and habitat loss. Specifically, I will compare populations of eight co-occurring Centris species in unfragmented versus highly fragmented areas of a global biodiversity hotspot, the Brazilian Cerrado savanna, to (i) investigate if the genetic diversity, gene flow and genetic structure of populations is significantly correlated with the degree of fragmentation and (ii) if these genetic parameters can be predicted by a species diet and body size. By using mutualistic network analyses and pollination experiments I will also test if (iii) the effects of fragmentation and habitat loss on bee-plant-interactions and (iv) pollination vary depending on the diet of a Centris species with likely stronger negative effects (loss of interactions, pollen limitation) on specialists. The results of this project will be of importance for conservation management and the local economy as it will help to understand and potentially predict the threat risk of bee pollinator species due to environmental changes.

• DFG Programme: Research Grants