Date of Award:
Doctor of Philosophy (PhD)
James P. Pitts
Bees are necessary pollinators for a vast array of different plants, including many which we rely on for food. In order to grow sufficient crops to feed the world’s growing population, we need to make sure our crops are visited by the most effective possible pollinators. However, this is complicated by the fact that there are over 4,000 bee species in North America, many of which vary in their pollination effectiveness and are difficult to identify. My dissertation’s first two data chapters focus on classifying the species of the xeric solitary bee group Anthophora subgenus Micranthophora, including seven newly described species, while also providing identification resources for telling them apart. With this group’s classification fixed, my third chapter then uses differences in the DNA of these species to reconstruct evolutionary trees of their relationships; those with more similar DNA sequences are grouped more closely together. I then use powerful modern methods to and determine how quickly new species have arisen throughout the entirety of the group’s evolutionary history, in order to determine how desertification has influenced the evolution of these xeric bees. My results suggest that the Neogene Uplift, a mountain-building event, initially increases their diversification rates, but climatic cooling and niche competition later greatly decrease these rates. Finally, my last chapter looks at bee evolution from a contemporary perspective, viewed through the lens of a new species of bee that actually excavates its nests in sandstone, Anthophora pueblo, despite the obvious time and energy costs of this behavior. In addition to describing this fascinating new species, I also use interdisciplinary methods from biology and geology to demonstrate that, although they prefer to use weaker sandstone, intermediate levels of sandstone hardness are likely beneficial to them, enabling future generations of their relatives to reuse nest tunnels for many years without excavating. Preliminary evidence also suggests that these bees benefit from protections afforded to them against parasites and pathogens that can destroy their nests and kill their offspring. Overall, this species will provide a terrific system for future studies of bee evolution and life history trade-offs. By performing these studies, my dissertation will enable a wealth of additional studies on these poorly known solitary bees.
Orr, Michael C., "The Biogeography and Nesting Biology of Anthophora, with a Revision and Phylogeny of the Anthophora (Micranthophora)" (2017). All Graduate Theses and Dissertations. 6759.
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