My research spans diverse study organisms and study systems. The central goal that drives my research program is a desire to understand the processes that generate spatiotemporal dynamics in populations and communities.
Insect Physiological Tolerance
The ability to tolerate and resist stressful abiotic conditions (such as heatwaves and droughts) shapes the geographic range a species can inhabit, their population dynamics, and individual behavior and activity patterns. As the world changes, a species' physiology will contribute to which populations will thrive and which will suffer. My postdoctoral research explores thermal tolerance and desiccation resistance in beneficial and pest insects. Specifically, I am trying to understand how different environmental stressors interact, how physiological tolerances vary over an individual's life history, and how interspecific variation in physiological tolerance shapes variation in community composition.
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Consumer-Resource Interactions
Consumer-resource interactions are the fundamental building block of food webs and can generate cyclic population dynamics. During my PhD, I studied consumer-resource interactions between non-biting midges and algae at Lake Mývatn, Iceland. At Mývatn, midges show large fluctuations in abundance consistent with consumer-resource dynamics, but the frequency of these fluctuations are atypical for classical C-R dynamics. One possible reason for these complex dynamics is that midges feed on living algae that actively grows in the sediment and dead algae stored in the sediment. In studies combining experiments, theory, and observational data, I explored how midge consumption, algal production, and detrital storage interact to shape long-term patterns in midge survival, growth, and reproduction. From this work, I found that midges benefit from a consumption rate that maximizes algal population growth and when algal growth is too low to support midges, they draw down the organic content in the sediment, linking the dynamics of detritus and algae in the lake.
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Effects of Recent Climate Change on Trends in Insect Populations
A warming climate is expected to have a number of different effects on insects, including poleward shifts in species ranges, earlier timing of life history events, and reductions in average adult body sizes. Alongside climate change, organisms have also faced a number of other stressors that may drive patterns in species ranges, phenology, and body sizes, such as altered landscapes, nutrient enrichment, pesticide use, and the introduction of nonnative species. All of these changes have the capacity to interact with each other, making trends complicated in nature. During my PhD, I explored how warming air temperatures interacted with changes in midge abundance and resource use to shape variation in midge body sizes over nearly 40 years at Lake Mývatn. Midges decreased in body size as temperatures warmed, but this shrinking was offset by a decrease in population size, which increased per capita food availability.
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Ecosystem Linkages
The movement of organisms across ecosystem boundaries can have significant effects on the dynamics in those ecosystems. While Lake Mývatn is highly productive, the surrounding landscape is relatively low productivity. Therefore, when adult midges emerge from the lake in large numbers it represents an important resource for the terrestrial food webs around the lake. Using experiments, models, and statistical analyses, collaborators and I have explored the consequences of midge populations on the surrounding landscape. From this work, we have learned that midges can have large and lasting effects on terrestrial communities. For example, I found that the long-lasting shifts of the plant community induced by experimental midge addition to heathland plots results a shift in the composition of the herbivore taxa.
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Effects of Landscape Modification on Bee Communities
Prior to graduate school, I explored the consequences of habitat loss and fragmentation on bee communities in the Chocó biodiversity hotspot in Ecuador and the effects of pine management on bee communities in the southeastern U.S. In both systems, land use contributes to local and regional species diversity of bee communities.
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