Projects

In general, we are interested in developing integrative projects related to mathematical applications related to behavior, evolution, or conservation. Previous and current projects range from mechanistic understanding of how mate preferences can spread through populations, to studying the long-term stability and viability of natural and endangered populations.

Below are recent examples of iibbs/BioMath projects:

Population dynamics of eastern bluebirds. We are studying breeding demographics, fitness metrics, and dispersal of an eastern bluebird metapopulation where sub-populations experience varying levels of anthropogenic disturbance. So far our data indicate that the unpredictability of disturbance is the most important paramater affecting the fitness of these local birds populations. We will be building population viability and source-sink models to understand the longterm consequences of human disturbance on this, and similar, species. Members involved in this project:

• Undergraduate students: Judy Che, Rachel Biondolillo, Mark Cathey
• TNCC summer interns: Tondra Robinson, Cristina Brittian
• Graduate students: Caitlin Kight, Josh Le Clerc, Holly Lang
• Faculty: John Swaddle, Dan Cristol, Sebastian Schreiber

Source-sink implications of wetland mitigation. The initial goal of this project was to determine whether current national wetland mitigation policy is adequate to provide for sustainable populations of birds. When a wetland is destroyed by development, the responsible party must build or restore a replacement wetland of the same acreage. We first compared the productivity and diversity of birds nesting on natural versus created saltmarshes. Created marshes did not provide as suitable a breeding site as natural wetlands, and are more likely to be population sinks where individual birds do not replace themselves during their lifetime. Using mathematical models of source-sink dynamics we are determining how much replacement wetland is necessary to offset the loss of more productive natural wetland, and have found that after a certain threshold of wetland destruction is reached, no amount of replacement wetland can sustain a bird population. Members involved in project:

• Undergraduate student: Jason Keagy
• Graduate student: Dave Desrochers
• Faculty: Dan Cristol, Sebastian Schreiber

Mechanisms of inheritance of sexually-selected traits. Most current models of sexual selection (selection relating to mating success) stipulate that mate preferences are inherited through organic genetic mechanisms. However, there is little information about whether mate preferences are genetically heritable and what form of genetic architecture underlies variation in preferences. In addition, we have exciting new evidence that mate preferences can be inherited through non-genetic, social mechanisms and can be largely moderated by environmental variation. Therefore, several students are further exploring (empirically and theoretically) the relative importance of genetic and non-genetic mechanisms to inheritance of mate preferences and to the evolution of sexually selected traits.

• Undergraduate students: Laura Page, Carling Sitterley, Mark Cathey, Mo Correll, Sabina Malhotra
• Graduate student: Amanda Houck
• Faculty: John Swaddle, Tim Killingback

Population structure of diamondback terrapins. We are studying the size and age structure of a population of diamondback terrapins living in an island-marsh complex in the lower York River, VA. We are determining the nesting success of female terrapins and quantifying 1) nest predation on eggs, and 2) crabpot mortality on juveniles and adult males. We will use these data to build a population viability model to guide possible management decisions for predator control and/or fisheries regulations near islands where terrapins are nesting. Members involved in this project:

• Undergraduate student: Matthew Wolak
• Graduate student: Victoria Ruzicka
• Faculty: Randy Chambers, Sebastian Schreiber

Effects of Mercury on birds of the Shenandoah River Valley . There has recently been a lot of concern about the effects of mercury contamination on humans and wildlife.  Mercury pollution now arises mostly from coal-burning power plants and other diffuse sources, but historically it was dumped in huge quantities directly into rivers.  One such site is the South River , a major tributary of the South Fork of the Shenandoah River in Central Virginia .  Until 1950, enormous quantities of mercury were dumped into the river at Waynesboro , and it has now worked its way >50 miles downstream, as well as into the flood plain and food web.  I am interested in finding out whether mercury contamination is affecting the fitness of birds along the Shenandoah River .  We have already detected high levels of mercury in several bird species, and are now focusing in on population level effects of this mercury toxicity. If populations are reduced along the river, it may serve as a population sink, or “attractive nuisance”, drawing prospecting birds away from population source areas such as the adjacent Shenandoah National Park . Modeling the system's metapopulation dynamics will help to better estimate the impacts of the mercury contamination on nearby and distant avian populations.

• Undergraduate students: Ravi Jefferson-George, Sean Koebley, Adrian Monroe
• Graduate students: Ariel White, Rebecka Brasso, Scott Friedman, Anne Condon
• Faculty: Dan Cristol, Rob Hicks, Sebastian Schreiber