DEPARTMENT OF MATHEMATICAL AND STATISTICAL SCIENCES
UNIVERSITY OF ALBERTA

PIMS-MITACS MATHEMATICAL BIOLOGY SEMINAR


MONDAY, March 21, 2005
3:00 - 4:00 p.m.
CAB 657

Dr. Cailin Xu
Department of Biological Sciences
University of Alberta

Seasonality and population cycles: forced prey growth or forced
functional response?

Population cycles of mammals have been recognized as a phenomenon of northern latitudes. Seasonality, relating to the annual fluctuation in climate and food resource availability, is greater at northern latitudes with ramifications for demography but also for foraging. The role that seasonality might play in cyclic and complex dynamics is examined by studying the consequences of seasonal forcing of demography versus the functional response. Complex dynamics for biologically plausible model parameters, are observed when periodic forcing is superimposed on the growth rate of prey as well as the attack rate in predator-prey systems that otherwise have asymptotically stable equilibriums.  Dynamical differences between these two cases also are examined. Our results imply that the place to look for an explanation for latitude-based population cycles appears not to relate to the functional response but to seasonal variation in demography.