• Dr. Kevin E. Bonine, Department of Ecology and Evolutionary Biology, and School of Natural Resources, University of Arizona
• Don Swann, Saguaro National Park

Objectve:

Our goal is to describe the population genetic structure of the canyon treefrog in the Rincon Mountains. Canyon Treefrogs (Hyla arenicolor) are currently abundant, providing an ideal study system for terrestrial ectothermic vertebrates of the rich riparian islands found in the Sonoran desert. Unfortunately, not all species of frogs in the Southwest occur in such high numbers, making study of these rarer species problematic. Habitat loss, global climate change, and disappearing surface water from continued overdrafting of local aquifers are causing a drop in riparian species populations. Assessment of the phylogeography of Canyon Treefrogs may provide a model for the distribution patterns of other anurans now isolated by habitat fragmentation.

By sampling multiple individuals from drainages throughout the Rincon Mountains, we will be able to accomplish several objectives:

1.) Identify mitochondrial DNA and microsatellite variation within and among Canyon Treefrog populations.

2.) Infer historical movements among Canyon Treefrog populations in drainages in the Rincons

3.) Test whether or not the genetic structure of Canyon Treefrogs is similar to that of the previously studied Lowland Leopard Frog (Rana yavapaiensis).

4.) Assess implications for Canyon Treefrogs, and other riparian species, of predicted future changes in surface water, precipitation patterns, and/or temperature.

5.) Develop a preliminary dataset that will facilitate expanded research and funding opportunities.

Importantly, the data will be assessed in light of information provided by Don Swann, a biologist at Saguaro National Park. He has a decade or more of data on abundance and distribution of surface water in the drainages we are sampling. These data will allow for more informed and sophisticated interpretation of observed patterns of genetic structure in Canyon Treefrogs, as well as for inferences about when and how individuals have historically moved around the landscape. Data on this currently abundant species will also allow for more informed understanding of other, more threatened ranid frogs.

Our results will provide insight into a number of questions about this riparian species. If individuals consistently move overland between drainages, resource managers will have to accommodate such movements in order to ensure continued persistence of viable populations; resource managers might then have to worry less about maintaining water in all drainages at all times. However, if data indicate that individuals move among populations by following drainages, this may have implications for land- and water-use patterns that are in conflict with human demands on similar resources. Moreover, predictions about physiological characteristics such as dehydration tolerance may be possible based on the findings from a fine-scale analysis of genetic structure. Predicted responses to large-scale climate change are also possible.