PARENT SESSION
Tuesday, August 8, 8:00-11:30 am
COS 19 - Population dynamics II: animals
L-4, Lobby Level, Cook Convention Center
Presiders: J Maerz
Insect outbreaks and synchrony: the interplay between stochasticity and dispersal in local and regional population dynamics.
Abbott, Karen*,1, Dwyer, Greg1, 1 University of Chicago, Chicago, IL
ABSTRACT- Many insect populations exhibit large-amplitude population cycles, which often occur in synchrony across large geographic regions. Theoretically, this synchrony can be caused by correlated environmental fluctuations or by dispersal of individuals among populations. In addition, stochasticity and dispersal can each bring about qualitative changes in the local population dynamics of the insects, either enhancing or damping population cycles. Using a series of simple metapopulation models for herbivorous insects, we explore the impact of dispersal and stochasticity on local dynamics and assess their roles in driving population synchrony. We find that the statistical distribution used to describe environmental stochasticity largely determines its strength as a synchronizing agent. We also find that different dispersal rules, which govern how many individuals disperse and how they distribute themselves in space, result in different degrees of synchrony. Finally, dispersal-induced population stability is more common under some types of stochasticity and with some dispersal rules. Amidst all this variation, an interesting pattern emerges: mechanisms that promote dispersal-induced stability also tend to promote asynchrony among populations. This finding emphasizes the relationship between local and regional population processes, and suggests that understanding regional synchrony may be an important step toward understanding the occurrence of large-amplitude insect cycles in nature.
Key words: population synchrony, insect outbreaks, dispersal