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At present, most turtles, all crocodilians, and several lizards are known to have temperaturedependent 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 I1 TSD geckos (Eublepharis macularius and Hemithecoryx caudicinctus) and comparing these preferences with those of a species with genotypic sex determination (GSD) (Cohoonyx 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 (32OC) for the species, E. mmlarius 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= k0.37) than were temperatures for either of the TSD species (E. m l n r i u s SE = 0.10; H. cuudziinctus SE = +_ 0.17), thereby further demonstrating temperature preferences within the TSD species.

IntroductionBlack (H. cracherodii) and white abalone (H. sorenseni) are federally listed as endangered species in the United States. Conservation efforts include captive breeding programs; however, determination of the reproductive state of individual abalone is notoriously difficult using traditional visual assessments. Ultrasonography is a well-recognized technology used to assess gonad reproductive condition accurately and nonlethally in cultured and wild fish, and more recently cultured red abalone (H. rufescens). Here, we implemented the use of ultrasound imaging technology to monitor the gonad condition of endangered black and white abalone.MethodsRepeated ultrasound assessments of the gonad were used to assess seasonal changes in reproductive development in wild black (n=20), and captive white abalone (n=25).ResultsA modified ultrasound gonad index score was developed to incorporate multiple species of abalone. The ultrasound index scores ranged from one to five, with an index score of one being the lowest (gonad margin is thinly wrapped around the digestive gland or not present) and an index score of five being the highest (gonad margin is thick and significantly compressing the digestive gland).ConclusionWe show that non-lethal ultrasound imaging technology is useful for tracking cyclical changes in the gonad reproductive condition as well as a more precise selection of individuals that are in peak reproductive condition for captive breeding programs.