April 11 2013

5:00 pm BSRB 154

EcoEvoPub Series

Graduate Student Presentations


Ryan Hannigan
Center for Tropical Research
Institute of the Environment and Sustainability

"A Continental Risk Assessment of West Nile Virus"

The distribution of West Nile virus (WNV), one of the most prevalent vector-borne diseases in the world, is potentially influenced by a number of environmental factors, including climate, vector and host distributions, and human-mediated dispersal. An accidental introduction occurred in North America in 1999, and since then the disease has spread rapidly across the continent, leading to annual avian and mammalian epidemics, and posing a serious health risk to humans. I will present results of models relating WNV incidence under current climate conditions using a dataset on WNV infections in vectors and hosts collected from 2003 - 2011, in conjunction with observed climate variables that capture ecological surface attributes. These models, dependent on both temperature and precipitation variables, are highly accurate at predicting the current spatial distribution of West Nile virus on a continental scale, and help to explain extreme avian demographic changes during this time period. Understanding the role of climate in the spread and proliferation of WNV will improve geographic risk assessments for particular viral hotspots, and will shed new light on how incidence may be impacted under climate change.

W. Tyler McCraney
Department of Ecology and Evolutionary Biology

"Rampant drift in artificially fragmented populations of the endangered tidewater goby (Eucyclogobius newberryi)"

Habitat fragmentation and its genetic consequences are a critically important issue in evaluating the evolutionary penalties of human habitat modification. Here I examined the genetic structure and diversity in naturally subdivided and artificially fragmented populations of the endangered tidewater goby (Eucyclogobius newberryi), a small fish restricted to discrete coastal lagoons and estuaries in California, USA. I used five naturally fragmented coastal populations from a 300 km spatial scale as a standard to assess migration and drift relative to eight artificially fragmented bay populations from a 30 km spatial scale. Using nine microsatellite loci in 621 individuals, and a 522-base fragment of mitochondrial DNA control region from 103 individuals, I found striking differences in the relative influences of migration and drift on genetic variation at these two scales. Overall, the artificially fragmented populations exhibited a consistent pattern of higher genetic differentiation and significantly lower genetic diversity relative to the naturally fragmented populations. Thus, even in a species characterized by habitat isolation and subdivision, further artificial fragmentation appears to result in substantial population genetic consequences and may not be sustainable.

THURSDAY, April 11, 2013















































































































































































































































































































































































































































































































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