Thermoregulation and Species Diversity Among Badgers

Abstract

Investigations into thermoregulation of homoeothermic species, such as badgers, suggest validity of Bergmann’s rule, which establishes the relevance of surface area to volume ratio in relation to efficient heat retention of an organism (McNab, 1971). Allen’s rule builds on this concept by identifying that average relative appendage size is smaller in organisms inhabiting cold climates, thus resulting in proportionally reduced surface area, which aids in heat retention (Serrat et al., 2008). Variation in species that deviate from these principles can be investigated for positively adaptive traits, which compensate for less efficient ratios in a given climate (Brown and Lasiewski, 1972). Observing these variations among badger populations can offer further insight into the uniqueness of this a species. The diversity among badgers inspired the investigation of surface area to volume ratio, as well as tail length variation, across four genera of badgers: Burmese-Ferret badger, Asian badger, American badger, and European badger. We hypothesized that organisms with a smaller surface area to volume ratio retain heat differently than those with a higher ratio. It is predicted that larger organisms with a smaller ratio will retain heat more efficiently and absorb heat at a slower rate than those with smaller size and larger ratio. We subjected four clay cubes designed relative to these species models to the same methods of heat exposure and collected information on temperature change in the cubes after enduring the outlined conditions. Findings are in alignment with these predictions, showing that smaller clay models absorb initial temperature at a faster rate than larger models, while larger models retain core temperature over a longer period of time. Other studies have found similar results.