International Journal of Comparative Psychology

Investigations of dominance behavior and its relationship to  calcium gland size were conducted in the asexual gecko, Lepidodactylus lugubris. In an initial study, geckos,immediately after laying eggs, were randomly assigned to one of six groups where time of social contact (2 vs. 7 days) and type of social contact (direct experience with a gravid or non-gravid gecko or indirect experience) were varied in a 2 X 3 factorial design. Behaviors displayed by geckos in social contact were system atically recorded. Dominance hierarchies were readily formed between gecko  dyads that received 7 days of social contact with each other. Dominance was not related to gecko size or reproductive state. A second study examined the relationship between dominance, calcium gland size and egg development. Geckos were housed in groups of 4 for 28 days and were subsequently transferred into either dyads or housed individually for an additional 28 days. During the final 28 days, half of the geckos received extra calcium. Dominance, size of calcium glands and egg development were recorded. Dominant geckos developed a greater number of eggs and had larger initial  calcium glands than subordinates, but extra calcium was not related o gland size. The function of dominance in L. lugubris populations may be two-fold: it may act as a spacing mechanism in low density environments and may facilitate the development and laying of eggs by more nutritionally fit individuals in high density environments.