Dr. Arthur E. Weis will talk on
Phenology as Habitat Choice in Plants: How and why the when of germination and flowering determines the what and who of fitness impacts, everywhere
at 12:30 in the EEB lounge (BioSciences 4338)
Correctly timing the transition from one life history stage to the next is key to individual survival and reproduction. The date of a transition has no intrinsic fitness impact. Rather, selection on the timing of birth, dispersal, reproduction, dormancy, etc., arises because individuals that transition at different times experience different temporal segments of the general environment. Climate, resource availability, and exposure to enemy/mutualistic/competing species can change predictably over the course of the seasons. Individuals occupying different temporal segments can have predictable fitness differences. In addition, differences in transition time also expose individuals to different segments of the social environment.
In populations that are heterogeneous for phenology, some sets of individuals are more likely to interact than others. Partitioning total selection on phenology into components caused by the general and social environment is fraught with difficulty. The temporal general and social environment are inevitably correlated. Further, phenological traits by necessity impose confounding genotype-environment correlations. I will present three experiments with Brassica rapa that manipulate these correlations to examine components of selection on germination and flowering time. One manipulates the length of the growing season to examine the fitness function for flowering time. A second contrasts selection on flowering time through female and male function by breaking the genetic correlation between mates (eliminating assortative mating). A third reveals that asymmetric competition between early and late germinants gives rise to individual and group components of selection.
After 19 years in southern California, Dr. Weis returned to the land of four seasons to take directorship of the Koffler Scientific Reserve at Jokers Hill. He lives at the reserve and has a research laboratory there. His main lab and greenhouse space are on the main campus of U of T, where Dr. Weis is a professor in the Department of Ecology and Evolutionary Biology.
Recently, Dr. Weis has become interested in the selective pressures imposed by climate change. In California, his lab used the “resurrection paradigm” to demonstrate a rapid adaptive response by field mustard, a winter annual, to an extended drought. At KSR he is continuing to work on the evolution of phenology to lengthening growing seasons.
The Weis lab website can be found here.