PARENT SESSION
Symposium 18: Biological Invasions in a Time of Global Change
Organized by: J Weltzin and J Dukes
Thursday, August 7. 8:00 AM to 11:30 AM, SITCC Chatham Ballroom C.
Biological invasions, stochastic events and global change: an uncertain world becomes more uncertain.
Mack, Richard1, 1 Washington State University, Pullman, WA
ABSTRACT- Environmental stochasticity, random variation in the environment that affects an entire population (e.g. year-to-year changes in the abundance of a population's predators and parasites), presents threats to the survival of all populations; small populations are especially vulnerable. Most immigrant populations of plants are small. Their extirpation is often caused by random events that are catastrophic for populations that cannot withstand large fractional reductions in size across consecutive generations. Predicting whether any immigrant population will persist is daunting, given not only the number of chance environmental events, but also the simultaneous influence of a population's size and the diversity and character of its genotypes. These predictions, however daunting, most usefully involve naturally occurring populations for which the amplitude of expression of environmental factors is known. Climate change, which is only one component of future global change, could directly and indirectly alter not only the direction but also the amplitude, periodicity, and duration of environmental stochasticity. These climatic changes could substantially increase the difficulty of predicting the fate of an immigrant population. Computer simulations of changes in weather that are beyond the range of a locale's current regimen offer insight into how novel climatic dynamism could complicate predictions on the fate of immigrant plant populations. As more species become incorporated into international commerce, the role of environmental stochasticity in determining their persistence and spread in new ranges will be shaped by ongoing permanent changes in the global environment.
Key words: biological invasions, environmental stochasticity, global change