Research Interests
Biological diversity is created and shaped through species interactions. The extent of these interactions can vary from loose ecological associations to tightly coevolved relationships - those in which evolutionary changes in one species cause reciprocal evolutionary changes in the other species. A framework for studying coevolution is the geographic mosaic theory of coevolution, which focuses on the role of population-level processes in shaping coevolved relationships. An outcome of these processes is that levels of association between coevolved species can differ within their geographic ranges.
For my thesis, I am building a system to test hypotheses that stem from the geographic mosaic theory of coevolution in a host-parasite system. The host is the ant species, Cephalotes atratus, and the parasite is the fungal species, Cordyceps kniphofioides. This particular host-parasite system is ideal for examining this theory due to unique characteristics of the ant and fungus. Cephalotes atratus is a widely distributed tree-dwelling ant, ranging from Panama to northern Argentina, and it occurs at low elevations in a variety of different habitats. Because ants do not typically disperse far from their natal colony, they usually exhibit patterns of genetic diversity that correspond to distance, such that colonies that are geographically close are genetically similar. The Cordyceps parasite is obligate and host-specific, meaning it does not persist outside of its’ host and that it does not infect other host species. These fungi infect insects, causing them to climb trees so they die in elevated locations. The fungus consumes the insect tissue, and then produces an elongated fruiting body containing spores that disperse aerially to infect other insect hosts. Because the parasite is so tightly coupled to its’ host, I predict this system will exhibit different patterns of association across its’ geographic range and that reciprocal evolutionary changes are driving the geographic differences in this system. Currently, I am examining the genetic structure of the host and parasite on both broad and fine geographic scales.
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