Multi-scalar drivers of native bee community composition and population genetic structure in human-altered landscapes
MetadataShow full item record
One of the most well-documented ecological impacts of human-caused landscape change is the fragmentation of natural habitats by human infrastructure, with potential implications for 1) community composition, and 2) species-level gene flow patterns. By including quantifiable measurements of local habitat composition, regional land-use, and the composition of the landscape matrix in ecological studies, we can better understand how multi-scalar environmental factors drive changes in wildlife community composition and dispersal processes, and infer subsequent consequences for ecosystem functions and services across human-altered landscapes. Pollination is a critical ecosystem service driven in part by wildlife community composition and dispersal processes, but despite the importance of bee pollination for ecosystem function, very little is known about how land-use drives native bee community composition and their population gene-flow patterns. This research addresses this literature gap by investigating native bee communities (Chapter 1) and native bee gene flow (Chapter 2) across heterogeneous human-altered landscapes in Texas, and proposes methods for expanding conservation genetic research of pollinators using curated bee specimens (Chapter 3). In Chapter 1, we conducted an extensive survey of bee communities across two urban landscape gradients in Austin and Dallas, Texas, USA comparing communities within agricultural and native grassland habitat types. In Chapter 2, we investigate the genetic structure and gene flow patterns of the native eastern carpenter bee, Xylocopa virginica across a 450 km corridor spanning multiple land-uses in Texas. In Chapter 3, we test the effects of sampling and curation methods on next-generation sequencing of three widespread North American native bee species. Our results indicate that the composition of regional land-use differentially impacts bee abundance and diversity depending on local habitat management and between bee functional groups, and that contemporary land-use as well as regional and fine-scale geographic distance influence the gene flow patterns of a large wood-nesting bee. Lastly, we find that sampling and storage method influence sequence assembly quality, and that curated and trapped specimens can be successfully utilized for next-generation sequencing research.