Amphibians have
been experiencing extinctions and declines at unprecedented rates, and as
ectotherms, they may be particularly sensitive to environmental changes.
Determining the best way to predict body temperatures in the field is a
critical tool to better understanding the adverse impacts of environmental
changes on this imperiled taxon. Using agar models, mechanistic niche
modelling, and field collected data, we attempted to accurately model the range
of body temperatures that Green frogs, Lithobates
(Rana) clamitans, a semi-aquatic species, may experience at three sites in
Northwestern Pennsylvania. Agar models containing temperature loggers were
deployed, and plasti-dip was utilized to create permeable and non-permeable models
to encompass the potential range of cutaneous water loss seen in nature. We
then employed the program Niche Mapper™ to model the body temperatures of
amphibians in their environment utilizing data on microclimate and amphibian
physiology. Both night and day surveys were also conducted to collect actual
frog body temperatures using non-contact infrared thermometers. Temperatures
experienced by agar models were greatly influenced by model permeability,
despite occupying similar microhabitats. These data in conjunction with Niche
Mapper™ projections provided an encompassing gradient for temperatures of live
anurans. Moving forward we are working to refine both environmental and
physiological Niche Mapper™ parameters to improve the accuracy of predicted frog
body temperatures further. Ultimately,
the ability to model amphibian body temperatures will allow us to predict
changes in behavior, physiology and potentially also disease risk in response
to changes in the environment.
