Research Interests
I have broad interests in the ecology and evolution of wildlife, especially groups of conservation concern. My PhD research utilized both field and laboratory techniques and is focused on native bees persisting in human-altered landscapes. The headings below provide more specific information about my PhD thesis work. Past research topics have included managing habitat in former agricultural landscapes for bird and butterfly conservation in the UK, and landscape genetics of various freshwater fish species across the world. These projects have included conservation genetics of native trout in Colorado, understanding complex evolutionary patterns of immune genes in arctic charr in Scotland, UK, and of host-parasite interactions in stickleback in Vancouver Island, BC, Canada.
Urban community ecology of native bees
Although urban areas are increasingly shown to be important habitat for native bee pollinators, very little is known about how local management interacts with landscape context to affect bee community composition and biodiversity. My work comparing bee communities in agricultural spaces and grassland fragments across urban landscape gradients in Dallas and Austin, TX has shown that native bee communities retain relatively similar levels of diversity in grassland fragments, regardless of their location in urban core or rural semi-natural areas. However, bee communities in gardens and farms located within highly urbanized areas were significantly less diverse than at farms that were surrounded by a higher percentage of natural land. This is the first demonstration of distinct local management types differentially affected by regional landscape context to affect urban bee communities.
Landscape genetics of carpenter bees
I use genetic tools to understand how organisms can move through and persist in human-altered landscapes. I am currently analyzing polymorphic microsatellite data from the Eastern carpenter bee, Xylocopa virginica. This bee is one of the largest bees in N. America, and is thought to often utilize human-associated materials such as firewood and lumber to make their nests, and will often re-furbish nests of previous generations, but how they move through human altered landscapes is currently unknown. By investigating levels of genetic isolation between sites and effective population size we can understand how far these bees disperse. And by integrating that information with geographic data, what habitats limit or facilitate that dispersal. I am also working on adding analysis of the small carpenter bee, Ceratina strenua, a close relative whose nesting behavior is similar to X. virginica but is much smaller in size, and so dispersal patterns may be more restricted by human land-use change. This project will utilize next-generation sequencing techniques for both species and is funded by the National Science Foundation Doctoral Dissertation Improvement Grant.
Size difference in Xylocopa virginica and Ceratina strenua (photo: (c) Clay Bolt)
Landscape effects on plant-pollinator interactions
Loss of species caused by habitat loss and fragmentation may lead to a loss of interactions, and mutualistic interactions such as plant-pollinator relationships may be strongly affected by habitat fragmentation, because long-term population persistence of both plants and pollinators relate to the number and intensity of their connections. Ecological network analysis methods are powerful tools to study how plant-pollinator interactions vary across a fragmented landscape. Previous studies using these approaches have shown that landscape changes such as deforestation and agricultural intensification affect the structure of mutualistic networks, although studies on the effects of urbanization on plant-pollinator networks are few. By visualizing and comparing key network metrics across urban landscapes we can better understand how the community of interactions may change as urbanization increases, and understand the system’s structure and resilience to environmental change. In a fragmented landscape, available resources tend to be concentrated in isolated habitat patches, and so pollinator species may become more generalist to cope with lower resource levels overall. I am currently analyzing flower visitation data as well as pollen samples from netted bee specimens to determine if land-use affects the structure of these plant-pollinator networks. This project is funded in part by the Native Plant Society of Texas Ann Miller Gonzales Memorial Grant. I have also mentored several high school students from underserved communities under this project; these students helped collect pollen data and designed and presented their own research projects utilizing this dataset.
14% Urban
67% Urban
Examples of plant-pollinator networks from two sites, one with low urban development, and one high. Each node represents a pollinator species (top) and flower species (bottom). Thickness of line indicates frequency of interaction.
My student DJ Ojeda extracting pollen from netted bees for later identification. She presented her work for the Crockett High School research partnership with UT. She is now an award-winning freshman at UT, double majoring in Environmental Studies and Buisness.
