ZOOLOGY
Ecological Determinates of Geographic Range Size in North American Amphibians. SHELBY R.
TIMM* and CY L. MOTT, Department of Biology, Kentucky Wesleyan College, Owensboro, KY
42301
Amphibians are one of the most endangered vertebrate groups on Earth, with populations
declining rapidly and over a third of all species at risk of extinction. Little is known of their
geographic distributional patterns relative to other widely investigated terrestrial vertebrates,
such as mammals and birds, though knowledge of such patterns would inform management
decisions based on abundance and spatial distribution. The difficulty in studying population
biology is understanding which environmental factors, as well as which life history
characteristics, affect species’ range sizes. We examined a wide array of morphological,
physiological, and behavioral characteristics using data from AmphibiaWeb to determine which
factors are most strongly associated with variation in geographic range size. Overall, factors
such as reproductive strategy, elevational range, and clutch size were positively associated with
amphibian range sizes, and species that exhibited breeding migrations were more likely to
exhibit large range sizes. This method of examining morphological, physiological, and
behavioral characteristics as determinants of range size could provide an inexpensive method
for utilizing publicly available data to assess species’ risks of extinction.