Susan Kalisz      Staff     Undergraduate Researchers     Former Members

 

Post Doc

Rachel Spigler

As an evolutionary ecologist, I am fascinated by the interplay between ecological and evolutionary dynamics. In particular, I am interested in the evolutionary ecology of plant reproductive systems. Using a combination of observational field studies, manipulative field and greenhouse experiments, and a suite of genetic tools, my research answers questions about how ecological and evolutionary dynamics of plant mating systems and sexual systems are linked to population-level processes, ecological context, and genetic processes. In my past (and ongoing) work, I focused on reproductive Allee effects in natural plant populations, including effects on the mating system, and on the ecological and genetic factors influencing the evolution of separate sexes (dioecy).

As a Postdoctoral Researcher in the Kalisz lab, I will be using demographic modeling to investigate how ecological interactions influence trait variation and plant population dynamics (evolutionary demography). In addition, I am continuing to conduct studies that address how ecological context can influence mating system evolution. By merging these approaches and tools, my goal is to illuminate the evolutionary, ecological, and demographic consequences of changes in reproduction and the mating system. More broadly, such work can help improve our understanding of how population dynamics can influence the evolution of traits and how trait variation and evolutionary change can influence population dynamics.

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Graduate Students

Nathan Brouwer

I am a fourth-year doctoral student studying the demography and life history of perennial plants. I'm interested in the ecology and evolution of long-lived organisms and how life histories and demographic rates play out when there can be time lags and deferred costs to previous events and choices. For my dissertation I am working with two long-lived perennials, Mainthemum racemosum and Polygonatum biflorum , that frequently enter periods of extended dormancy. Extended dormancy occurs when a perennial plant does not emerge during its normal growing period and spends one or more years below ground before appearing again in a subsequent growing season. These two common understory perennials typically have 10-30% annual dormancy rates. Dormancy is more common in plants that have been recently browsed by white-tailed deer, the most important herbivore in the eastern deciduous forests where I work. However, there is usually a time lag of one year before browsed plants go dormant, and many browsed plants do not become dormant while many non-browsed plants do. I am therefore using long-term demographic data and field experiments to assess how different life history events and ecological interactions might affect dormancy rates. This work will result in matrix population models that will allow me to explore the causes and consequences of extended dormancy and the demographic influences of time lags.

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Alannie Grant

 

 

 

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Chris Heckel

Unification of ecological theory, in part, hinges upon a fuller understanding of the dynamic nature of species interactions. It is important that species interactions be addressed within their biotic and abiotic context. Positive and negative interactions of species can differ significantly among sites and, across the landscape, the strength or effect size of species interactions are modulated by the biotic and abiotic contexts. Therefore, the identity and abundance of individual species within a community and the population dynamics of those species are all context dependant. Experimental and observational research that addresses how species interactions change across biotic or abiotic gradients can improve our predictive ability regarding community structuring. In my dissertation research (5th year), I use experimental and observational methods to test how changes in the biotic context, for example increases in herbivore pressure on focal palatable species, can alter population dynamics of unpalatable species. I first ask, do unpalatable plants benefit when herbivore effects are high? Are their populations stable? Do plants change their reproductive allocations strategies in a response to population sex ratios that are determined herbivore-dependant contexts?

Thus far, I have found that unpalatable plants may experience costs as a result of increased herbivore activities. My results suggest that herbivore effects on soil quality may be the pathway through which herbivores negatively indirectly affect unpalatable plant species.

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