Susan Kalisz Staff Undergraduate Researchers Former Members
Post Doc
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.
Graduate Students
I’m a second-year student working on refining my research ideas. My broad interests are in population ecology and its application to conservation biology. Population ecologists have recently identified a new factor in population dynamics known as “carry-over effects.” Most theory and empirical work on carry-over effects relates to the role of resource access in one season affecting population dynamics in a following season. I’m exploring how to extend the theory and empirical evidence of carry-over effects to other mechanisms that can affect population dynamics, particularly parasites. I’ll work with scientists at the National Aviary in Pittsburgh and the Carnegie Natural History Museum to explore these ideas in a migratory bird, the Louisiana Waterthrush. Dr. Kalisz and I are also working on a project looking at the role of whole-plant dormancy as a life-history trade off and bet-hedging strategy in perennial plants.
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.
I am interested in the study of conservation physiology, an emerging field that uses tools from the ecophysiology literature to study conservation issues. For my dissertation, I am studying plant-mycorrhizae mutualisms and the physiological impacts of mutualism disruption on the plant. Specifically, I use the mutualism between a common forest understory herb and its arbuscular mycorrhizal fungi to investigate how two major environmental stressors - 1) allelopathic invasion by garlic mustard, and 2) drought - can disrupt this mutualism and the ultimate physiological consequences. Because many native forest herbs are perennial, it can be difficult to quickly detect environmental impacts on their population size, structure, and growth. Using an ecophysiological approach, I have shown that within a single growing season, garlic mustard can diminish soil respiration rates, photosynthetic rates, and overall carbon allocation patterns in a native forest herb. These physiological declines may, in part, help to explain the loss of native forest herbs from invaded sites. I am currently a fifth-year student here in the Kalisz lab and will be graduating in 2012.
In addition to my dissertation work, I am also a part of the team that created the most recent Act 54 report. Act 54 is a Pennsylvania law which mandates that every 5 years, a report must be published describing the aboveground impacts of belowground bituminous coal mining. As the lead biology graduate student on this project, I assisted in collecting macroinvertebrate data on several undermined streams in southwestern PA. The report is now published online. Check it out!
