WILMHOFF, C.D.*; PETREN, K.; Univ. of Cincinnati; Univ. of Cincinnati: Behavioral mechanisms underlying competitive displacment in a gecko community

Understanding the factors governing the distribution and abundance of organisms is a central goal of ecology. There is a wealth of information indicating that competition is an important factor in shaping distribution and abundance, but few studies have provided experimental evidence of the mechanism underlying competitive interactions. Understanding the mechanism or how competition occurs is critical to (1) the theoretical understanding of the role of competition in affecting distribution and abundance, and (2) understanding the invasion of exotic species. The present study examined the role of competition in shaping the distribution and abundance patterns of four clonal lineages (A, B, C, and D) of the gecko, Lepidodactylus lugubris and the mechanism underlying competitive interactions. All four clonal lineages inhabit many Pacific islands, but one lineage (clone A) is numerically dominant across most Pacific islands. In pairwise trials, individuals of clone A were superior competitors for a food resource. Behaviorally dominant individuals generally consumed more resources. Thus interference was determined to be the mechanism underlying most competitive interactions among clonal lineages. However, individuals of clone A also acquired greater amounts of food via exploitation competition when they were subordinate to other geckos. This study indicates that competition may be a factor governing the distribution and abundance of these clones and that clone A achieves its competitive superiority via interference and exploitation competition.