A comparative genomic approach of wild bee responses to urban ecosystems

• Applicant: Panagiotis Theodorou, Ph.D.
• Subject Area: Evolution, Anthropology ; Ecology and Biodiversity of Animals and Ecosystems, Organismic Interactions
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 490618597

Cities are expanding worldwide and urbanization is considered a global threat to biodiversity. The growth of cities results in an increase in impervious surfaces, habitat loss and fragmentation, invasion of non-native species and long term environmental changes associated with heat island effects and pollution. The combination of these effects constitutes a challenge for the survival and persistence of many species, including essential ecosystem services providers, whilst also imposing altered selective regimes.Recent reports of bee declines have focused attention on insect pollinators. Insect pollinators and more specifically bees are vital for wild and crop plant reproduction and thus critical for terrestrial ecosystems, the economy and food security. Urban ecology has provided significant insights on how urban environmental changes affect bee species community structure. However, we know little in regards to how the ecological impacts of urbanization affect the evolution of wild bee populations living in cities. Resources vital to bee pollinators such as floral food and nesting sites are likely to change with urban development and this could affect the distribution and abundance of individual species and communities. Several studies have shown that some bee pollinator groups are doing particularly well in urban habitats compared to others that are particularly sensitive to human-induced changes in the landscape. Here I propose to collect the first comparative dataset across four bee species that differ in their ecological attributes in multiple cities and nearby rural habitats to investigate how consistent and predictable the effects of urbanisation are on adaptive (i.e. selection) and non-adaptive (i.e. genetic drift and gene flow) evolution of wild bee populations. I will employ a population genomic approach using whole genome sequencing to generate SNP data for four keystone bee species to assess their genome-wide genetic diversity at SNPs and to partition genetic diversity into neutral and adaptive diversity, identifying both key demographic parameters from neutral markers and candidate loci undergoing selection for urban habitats. Apart from the great importance of comparing genetic diversity and gene flow in urban areas and adjacent rural areas across multiple bee species, this dataset will also yield important insights regarding wildlife conservation practice. More specifically, it will allow the assessment of the importance of certain urban habitats for gene flow and facilitate the identification of dispersal corridors between populations that may promote gene flow and prevent the loss of genetic diversity in urban bee populations. This will answer fundamental questions about the ecological health, persistence, and long-term stability of bee species in Germany and help inform conservation management to mitigate negative effects of cities on urban-dwelling organisms.

• DFG Programme: Research Grants