Print PageAltitudinal gradients provide a unique opportunity to examine the effect of phenology for population dynamics or species interactions over a manageable area. Such studies may provide insight into geographical variation in species interactions or the consequences of climate change for species distributions. The interaction between Publilia concava treehoppers and ants has become a model system for studies of mutualism. In this interaction, ants collect the carbohydrate-rich excretions of treehoppers and in return provide protection from predators and increase treehopper feeding rates. Here, I report on a three year study that has monitored the survivorship of P. concava across each of three sites in northwestern MA and surrounding areas of NY spanning an elevational range of around 500 m. I use a combination of statistical and biologically-based models to evaluate the pattern and causes of variation in survivorship and benefit from ant-tending across these sites.
Results/Conclusions
Results show a clear pattern of delayed phenology associated with increasing altitude. Similarly, treehoppers showed consistent and significant differences in patterns of survivorship and benefit across sites. Biologically based models are used to partition this variation into spatial, and phenologically mediated altitudinal, variation in benefit.
