Nest-site selection in two eublepharid gecko species with temperature-dependent sex determination and one with genotypic sex determination

At present, most turtles, all crocodilians, and several lizards are known to have temperature-dependent sex determination (TSD). Due to the dependence of sex determination on incubation temperature, the long-term survival of TSD species may be jeopardized by global climate changes. The current study was designed to assess the degree to which this concern is justified by examining nest-site selection in two species of Pattern II TSD geckos (Eublepharis macularius andHemitheconyx caudicinctus ) and comparing these preferences with those of a species with genotypic sex determination (GSD) (Coleonyx mitratus). Temperature preferences for nest sites were found to be both species-specific and female-specific. While H. caudicinctus females selected a mean nest-site temperature (32.4°) very close to the upper pivotal temperature (32°C) for the species, E. macularius females selected a mean nest-site temperature (28.7°C) well below this species» lower pivotal temperature (30.5°C). Thus, the resultant sex ratios are expected to differ between these two TSD species. Additionally, nest-site temperatures for the GSD species were significantly more variable (SE=±0.37) than were temperatures for either of the TSD species (E. macularius SE=±0.10 H. caudicinctus SE=±0.17), thereby further demonstrating temperature preferences within the TSD species.