Susan Kalisz

Department of Biological Sciences
University of Pittsburgh


Research Interests:

Research in my lab addresses basic questions in plant evolution and ecological genetics. One area of interest is the ecological and evolutionary causes and consequences of plant mating systems. Unlike the majority of animal species, mating systems in plants range from pure self-pollination to pure outcross-pollination and are highly variable among genera and species. Mating system traits, such as floral characters, are significant because the mating system defines how genes are passed from one generation to the next and in essence controls the evolution of all other traits of organisms. Finally, floral traits and plant-pollinator interactions are some of the most striking examples of evolution known in biology. We are interested in how plants evolve the ability to produce seeds when pollinator visitation is unpredictable within or among flowering seasons.

A second line of research investigates natural selection on and the demographic consequences of dormant seed banks in natural plant populations. In annual plants, not all seeds produced in one season germinate in the subsequent growing season. Instead, some seed do not germinate and remain alive forming a population of dormant seeds in the soil termed a seed bank. Most annual species and even many perennial plants form seed banks. We are working towards a general understanding of how seed banks function, both ecologically and genetically. Seed banks are significant features of plant life histories because plants emerging from the seed bank can restore low populations sizes. Seed banks can even buffer populations from extinction in the face of catastrophies. In addition, seed banks can store genetic variation not seen in the growing fraction of the population thus function as a repository of genetic diversity. Understanding the ecology and evolution of seed banks is central to the conservation and protection of native biodiversity.

The thread that weaves these apparently disparate research areas together is our fundamental interest in how adaptive evolution proceeds in the face of environmental unpredictability. Species that live in chronically variable environments often possess adaptations that may mitigate the consequences of the variation. Therefore environmental variation itself can select for suites of traits that allow plants to persist and reproduce, despite the unpredictability. Seed banks and the ability to self-pollinate in the absence of pollinators are primary adaptations possessed by many plant species that buffer the effects of temporal variability.

Since we are interested in how both ecological and genetic factors interact to shape the evolution of these traits, much of our research involves a combination of field and greenhouse experiments with native wildflower populations. The majority of our research uses Collinsia verna as a model system because it has a short generation time, is easily crossed, we have developed techniques for producing clonal replicates of individual genotypes and Collinsia verna is a member of a genus with +18 annual species whose breeding systems range from pure outcrossing to pure selfing.

We have several projects in progress in our lab, which range from the genetic to the community level and employ analytical methods that range from quantitative genetic analyses, demographic projection analyses to species richness and abundance metrics of communities. Detailed descriptions of our current research projects are available at our our lab website.