Bumble bee use of heterogeneous mountain habitats: A landscape genomic approach
Date
2023-05-09
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Abstract
Land use modifications and climate change are two of the major factors behind global biodiversity losses. The specific impacts and long-term implications of these changes have yet to be understood for many species. Bumble bees (Bombus sp.) are an important group of pollinators, especially in temperate and montane regions where they are relatively abundant. They are also facing global declines and range shifts. In this thesis I pose several questions investigating the relationship between bumble bees and mountain landscapes. I first ask whether bumble bee abundance and species richness are positively or negatively associated with measures of landscape fragmentation. I then demonstrate patterns of genetic and phenotypic diversity and differentiation in the high elevation taxa Bombus lapponicus sylvicola and assess hypotheses about mechanisms that could be causing the differentiation I observe. Lastly, I test whether gene flow in four bumble bee taxa has been restricted between habitats of differing elevations. To answer these questions, I sampled 22 species of bumble bees from 69 sites across a 40,000 km2 geographic range, where sites were selected to minimize correlations between variables of interest. I extracted DNA from 745 individuals of four different taxa, and used SNPs derived from ddRAD libraries to measure genetic diversity and gene flow. In this thesis I report higher abundance and species richness of bumble bees in locations where surrounding land cover has higher levels of complementation between nesting and foraging habitats, but that abundance and species richness decrease with other measures of fragmentation. I describe a new cryptic subspecies of B. sylvicola based on genetic and phenotypic diversity, and present evidence that it may have differentiated under conditions of gene flow based on adaptation to cold minimum temperatures. Finally, I present evidence that high elevation taxa appear to be able to exchange genes freely across elevations, while taxa associated with lower elevations display patterns of reduced gene flow across elevations. These findings have important implications for the conservation of montane bumble bee species and provide several avenues for future study and investigation.
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Keywords
Landscape Ecology, Population Genomics, Landscape Genetics, Bumble bee, Mountain
Citation
Clake, D. J. (2023). Bumble bee use of heterogeneous mountain habitats: a landscape genomic approach (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.