SYMP 4-2
Biodiversity across varying environments: Mechanisms of compositional stasis and change
Understanding mechanisms of compositional change is important given the many factors that may influence future biodiversity. To provide a long-term context for recent biodiversity changes, we investigate links between local biodiversity and environmental change over the past 21,000 years. We assembled records of fossil pollen genera from lake sediment cores in eastern North America and determined richness change at each site through time. We coupled these data with paleoclimate simulations, then examined the taxa and climates associated with richness changes to determine 1) if more compositional change occurred during times of rapid climate change and 2) whether the spatiotemporal patterns underlying taxonomic changes (i.e., average direction and distance of colonization or extirpation) were correlated with similar metrics of climate change.
Results/Conclusions
Mean richness across all sites did not significantly change through time. While the majority of sites showed no substantial directional changes in pollen richness, some individual sites had either significant increases or decreases in pollen richness through time. However, change in local pollen richness was not significantly associated with simulated local temperature change. These results suggest that environmental change maintains diversity in fluctuating environments by influencing colonization and extirpation of different taxa. We explore whether factors other than temperature may be playing a role in influencing changes in local richness and use other proxies such as plant macrofossils to determine whether they are more sensitive indicators of richness change through time.