Undergraduate Honors Theses

Thesis Defended

Spring 2013

Document Type



Ecology and Evolutionary Biology

First Advisor

Dr. Christy McCain


Understanding competitive interactions for resources within an ecological community is fundamental for understanding the life histories of organisms in that community. Interspecific competition (competition between members of different species over a limiting resource) is often studied between species of similar size or close evolutionary relationship. Competitive interactions between species of distant taxonomic relationship or very different sizes have been rarely studied. For 22 sites along three transects in the Colorado Front Range and San Juan Mountains, signs of potential competitive interactions between small mammals and ants along elevational gradients were examined. Abundances of ants and small mammals were determined through pitfall (trap sunk into the ground) and mark-and-recapture (trapping, tagging and releasing of animals for recapture to estimate population size) trapping techniques. Proportions of pitfall traps containing ants were determined and compared to the minimum number of mammals known alive (MNKA, number of individuals marked in a trapping effort) using Spearman’s rank-order correlation tests to determine correlations between variables. No direct evidence was found for competition between ants and small mammals (Spearman’s Rank Correlation Coefficient was 0), indicating little to no competition between ants and small mammals in these areas whether food or space resources are readily available. This study is the first of its kind conducted outside of desert ecosystems. Understanding the ecological community as a whole, including any and all possible competitive interactions, is fundamental in conservation efforts, especially as organisms expand into higher elevations historically located outside of their ranges.