Meeting Abstract

4.4  Jan. 4  Climate change and temporal variation in nesting biology of North American turtles JANZEN, F.J.*; GIBBONS, J.W.; GREENE, J.L.; IVERSON, J.B.; TUCKER, J.K.; Iowa State University; Savannah River Ecology Laboratory; Savannah River Ecology Laboratory; Earlham College; Illinois Natural History Survey fjanzen@iastate.edu

Altered phenology of reproductive events has been noted as a particularly key indicator of biotic response to contemporary climate change. However, most research has focused on a single population of a given taxon (oftentimes at the edge of its geographic range), yet meta-analyses use such data as a proxy for the entire species. Moreover, few sufficiently long-term studies of phenology in reptilian taxa have been published. We address the possibility of climate-altered reproductive phenology with long-term (greater than 10 years) data on nesting behavior in multiple populations of each of four genera of North American turtles (Kinosternon, Chelydra, Chrysemys, and Trachemys). We find that initiation of the nesting season has advanced significantly only in populations at the northern edge of the geographic range of a species. Populations located farther south within the geographic range of a species exhibited less marked temporal changes in nesting behavior. Although more thorough analyses remain to be performed, our preliminary assessments reveal that variation in annual heating degree days and mean annual temperatures covary with the nesting patterns we observe in these turtles. Moreover, we are now testing whether the significant temporal shifts in phenology in populations at the northern edge of the range reflect phenotypic plasticity or adaptive evolutionary changes.