Sherri Emer

Manouria emys, the Asian forest tortoise, has received recent attention because of its primitive characteristics within an advanced lineage and its unique reproductive behavior. Because of decreasing numbers and inconspicuous habits, little is known regarding the tortoise’s biology with the exception of its behavior. Observations of the daily activities of captive juveniles and of captive adult reproduction are numerous. Although captive husbandry programs in zoos have documented nesting behavior and have successfully hatched M. emys, data on sex determining mechanisms and sex ratios are absent. A total of 30 M. emys eggs were artificially incubated at five different temperatures, in constant humidity. Mean incubator temperatures were 24.99°C, 25.06°C, 27.18°C, 28.00°C, and 30.79°C. Incubation duration ranged from 60 days to 92 days, and hatching success was 50%. Sex determined by histology and laparoscopy resulted in male differentiation at low temperatures (24.99°C, 27.18°C) and female differentiation at high temperatures (30.79°C). Pivotal temperature was estimated to be 29.29°C. The following investigation into temperature-dependent sex determination (TSD), including its presence or absence, pattern, and pivotal temperature has implications for studies of adaptive significance of reproductive behaviors and of chelonian phylogenetic history. Additionally, the results can provide foundations for conservation management decisions and for captive breeding programs.
Manouria Session: Oral

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