Spatial Distribution and Activity Patterns in African Barking Geckos: Implications for Mating System and Reproduction

Abstract

We studied spatial clustering and activity patterns in the common Barking Gecko (Ptenopus garrulus garrulus) over the course of a breeding season in southern Africa. Only some populations exhibited significant clustering (two of six plots), suggesting that social and spatial organization varies according to factors such as population density and habitat. Clustering at our largest site was not influenced by soil temperature or prey availability, although burrow placement was significantly associated with vegetation coverage. We also examined the timing of the reproductive cycle by testing whether Barking Geckos exhibit protandry (male-first emergence). More males than females were active early in the breeding season and male territories were established before female emergence. Peak activity for 235 Barking Geckos at our primary study site was in late October, although males were significantly more active early in the season, consistent with the protandry model. The Barking Gecko mating system is most consistent with an iteroparous, harem polygynandry with an activity cycle that exhibits protandry. Our study highlights the importance of replicated spatial sampling for studies examining clustering and density effects on reproduction and mating systems. The temporal and spatial distribution of females in relation to key resources profoundly affects male mating tactics and, ultimately, the mating system (Emlen and Oring, 1977; Shuster and Wade, 2003). Males that are able to monopolize clumped resources, such as refuges or food, are likely to experience higher reproductive success by virtue of their perceived quality or simply by default. For example, in the lizard Uta palmeri, female distribution is driven by food availability. Reproductive success was best explained by a male's dominance and the quality of the territory that he controlled rather than by any intrinsic traits that the female might select (Hews, 1990). Alternatively, in systems where females have a strong mating preference, males may be the resource that females seek. This scenario can give rise to a polygynous mating system such as a lek, where females choose among males based on indicator traits (Hoglund and Alatalo, 1995).