February 12 2015

5:00 pm BSRB 154

EcoEvoPub Series

Graduate Student Presentations


Department of Ecology and Evolutionary Biology

"What can influenza transmission in ferrets tell us about pandemic potential in humans?"

In gain-of-function experiments, scientists increase mammalian transmissibility of avian influenza viruses in order to identify genetic factors that could lead to pandemic emergence in humans. These experiments have recently come under government scrutiny because it is not currently possible to assess whether the risk of viral lab escape is commensurate with their scientific and public health benefits. Although ferrets are the preferred model species for influenza infection, the quantitative relationship between transmission in ferrets and in humans has never been established. To address this gap, we reviewed and compared transmission estimates in ferrets and in humans. Our meta-analysis demonstrated for the first time that on average, transmission behavior in these two species is linked, and that ferret transmission data yields some power to classify strains with high or low probabilities of epidemic spread in humans. We also found that ferret experiments measuring respiratory droplet transmission have more power to identify strains of epidemic concern than experiments measuring direct contact transmission. But while ferret transmissibility mapped to human transmissibility on average, small sample sizes and biological variation made specific or definitive predictions on human transmissibility from individual experiments difficult. Respiratory droplet transmission in ferrets represents a potential first-line screening tool for pandemic potential in novel influenza viruses. However, these results would ideally be supported by follow-up studies in humans, which would not be possible for lab-created isolates.


Department of Ecology and Evolutionary Biology

"The importance of plasticity to plant drought tolerance: a global meta-analysis "

Many plant species are expected to face increasing drought under climate change. Plasticity has been predicted to strongly influence species' drought responses by widening their range of tolerable climatic conditions, but broad patterns in plasticity have not been examined for key drought tolerance traits, including the turgor loss or ‘wilting’ point (πtlp). This trait characterizes the leaf water deficit that induces cell collapse and wilting, and has been found to be strongly correlated with the leaf water deficits at stomatal closure, disruption of leaf water transport, and leaf death. As soil dries, plants have long been known to shift πtlp by accumulating solutes. We conducted the first global analysis of plasticity in πtlp (Δπtlp) and related traits for 283 wild and crop species in ecosystems worldwide. Drought tolerance plasticity was widely prevalent but moderate (mean Δπtlp = −0.44 MPa), accounting for 16% of post-drought πtlp. Thus, pre-drought πtlp was a considerably stronger predictor of post-drought πtlp across species of wild plants. For cultivars of certain crops Δπtlp accounted for major differences in post-drought πtlp. Climate was correlated with pre- and post-drought πtlp, but not Δπtlp. Thus, despite the wide prevalence of plasticity, πtlp measured in one season can reliably characterize most species' constitutive drought tolerances and distributions relative to water supply.















































































































































































































































































































































































































































































































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