New Zealand Statistical Association
2004 Conference

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Shirley Pledger
Victoria University of Wellington

Temperature-dependent Sex and Viability Determination

Joint work with Nicola J. Nelson, SBS, VUW; Nicola J. Mitchell, Dept. of Zoology, La Trobe University, Australia; Michael B. Thompson, School of Biological Sciences and Wildlife Research Unit, University of Sydney, Australia; Susan N. Keall and Charles H. Daugherty, SBS, VUW.

Many reptiles show temperature-dependent sex determination, in which the egg incubation temperature determines the sex of the hatchling. Existing models use logistic or the more general asymmetric Richards' curves to model the proportion of males as a function of temperature. We extend the models to allow for temperature-induced mortality, which will provide a better management tool for optimising certain objectives. An example is the tuatara, where global warming will increase the proportion of males. Maximising the number of live females from artificial incubation requires a temperature which is low enough to produce females but not so low as to increase egg mortality.