PARENT SESSION
Oral Session #71: Animal Population Ecology. Presiding: J. Dooley.
Thursday, August 9, 2001. 1:00 PM to 4:15 PM. Hall of Ideas J.
An experimental test of whether habitat heterogeneity buffers populations against the effect of climate variability.
Hoekstra, Jonathan1, 1
ABSTRACT- Habitat heterogeneity may reduce extinction risk for populations by providing micro-environmental refuges that buffer against climate-induced variability in population dynamics. If generally true, this could have important implications for how conservation biologists evaluate suitability of potential preserves and how they define habitat restoration and management goals. I experimentally tested whether growth trajectories of Drosophila melanogaster populations on heterogeneous habitats were less sensitive to seasonal climate change than replicate populations on homogeneous habitats. I established experimental populations in large field cages over landscapes of rotting apples during summer 2000. Within six blocks of cages, I manipulated shade cloth to create shaded and unshaded homogeneous habitats and partially shaded heterogeneous habitats. I previously demonstrated that individual survivorship and development time differ significantly between shaded and unshaded conditions. I then monitored adult abundance for 8 weeks (4 to 5 generations) to characterize growth trajectories. The protocol was repeated during autumn to assay the effect of seasonal climate change. I used functional data analyses to compare growth trajectories among treatments and seasons. Between seasons, the effect of shade cloth treatments reversed such that populations in shaded habitats were more productive during summer while those in unshaded habitats were more productive during fall. Populations in heterogeneous habitats sustained intermediate productivity during both seasons. These results suggest that habitat heterogeneity can buffer population dynamics if climatic variability effects a reversal of relative habitat quality.
KEY WORDS: habitat heterogeneity, population dynamics, extinction risk, Drosophila melanogaster