Demography In a Variable Environment

Collinsia verna

Temporal environmental variability can have devastating consequences for the persistence of plant and animal populations, including the loss of genetic variation and a greatly increased chance of extinction. However, species that live in chronically variable environments often possess adaptations that may mitigate these consequences. Seed banks are a primary adaptation many plant species possess to buffer the effects of temporal variability. Seed banks can restore populations following extinction of adults or years of complete reproductive failure, and they may serve as a repository of genetic diversity. To address the importance of seed banks to the persistence of genetically diverse plant populations, we are studying the demography and genetic population structure of Collinsia verna, a winter annual. This collaborative research (with Dr. S. Kalisz, University of Pittsburgh) examines the demography and genetic diversity of natural populations and experimental populations to which temporal variability is imposed. Specifically, we are comparing the demography and genetic variability of populations following recovery from a bottleneck of total adult extinction to populations experiencing smaller fluctuations in population size. These studies include demographic analyses of plant populations in variable environments and characterization of population genetic structure using allozyme electrophoresis and molecular DNA techniques. The results of this work will guide the establishment of conservation practices for plants and animals living in variable environments.

Relevant papers

Kalisz, S., and M. A. McPeek. 1992. The demography of an age-structured annual: Resampled projection matrices, elasticity analyses, and seed bank effects. Ecology 73:1082-1093.

McPeek, M. A., and S. Kalisz. 1993. Sampling and bootstrapping in complex designs: Demographic analyses. In (S. M. Scheiner and J. Gurevitch, eds.) Design and Analysis of Ecological Experiments, pp. 232-252. Chapman Hall, Inc., New York.

Kalisz, S., and M. A. McPeek. 1993. Extinction dynamics, population growth and seed banks: An example using an age-structured annual. Oecologia 95:314-320.

Kalisz, S., L. Horth, and M. A. McPeek. 1996. Fragmentation, isolation and the role of seedbanks in promoting persistence of Collinsia verna in isolated populations. In (M. Schwartz, ed.) Conservation of Highly Fragmented Landscapes. Chapman and Hall, Inc., New York.

McPeek, M. A., and S. Kalisz. 1998. The joint evolution of dispersal and dormancy in metapopulations. Archive für Hydrobiologie 52:33-51.