The Affect of Disturbance on Forests

In many forests, disturbances, such as fire, affect species diversity and coexistence. We consider the simple analogous case of a landscape populated by two species, one (first successional) species that grows back quickly after a disturbance and another (second successional) species that grows more slowly than the first, but has a long-term competitive advantage.  In the absence of disturbance, the second successional species will dominate the landscape, while if disturbance is frequent, the first successional species will be more successful.  We divide this theoretical landscape into patches and are studying the effects of patch-scale disturbance on the landscape-scale forest equilibrium.

Quorum Sensing

Quorum sensing is a mechanism by which certain bacteria can probe their environment and regulate gene transcription. These bacteria produce diffusible chemicals called autoinducers, which at high concentrations trigger a group response. Quorum sensing is widespread in the bacterial world, regulating biofilm production, virulence factors, motility and luminescence, among others. One of the most famous examples of quorum sensing exists in Aliivibrio fischeri, a bioluminescent bacteria that lives symbiotically with the Hawaiian bobtail squid. A.fischeri contains a model quorum sensing system, the LuxR-LuxI system. Our first paper analyzes the distance that an autoinducer signal in this type of system may travel. While conducting this research, we saw a spatially propagating wave in colonies of wild-type A. fischeri. We then developed a simple, biologically significant mathematical model that exhibits this traveling wave and analyzed it mathematically.

 

Rift Valley Fever

Rift Valley Fever (RVF) is a vector-borne disease that exists in most of Africa and in parts of the Arabian peninsula. RVF primarily infects livestock, but has also been found in wildlife and can be transmitted to humans. RVF is characterized by so-called “abortion storms” in which livestock experience a 90-100% abortion rate. As my cohort’s QSE³ IGERT project, we investigated the relative risk of RVF introduction to the US via an infected airline passenger. Our group also studied the optimization of early disease detection methods.

 

 

Marine Protected Areas

Marine protected areas (MPAs) are areas of coastline in which fishing is restricted or forbidden. MPAs are a primary tool for fisheries management and as such their affects on fish stocks has been scrutinized. Before our paper, several attempts at modeling MPAs had been made, but these models did not capture all of the empirically expected phenomena associated with MPAs. Namely, empirical results suggested that more mobile fish benefit from an MPA at least as much as less mobile fish. Here, we give models that could explain this result.
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