TSD in Reptiles How the physical and the physiological conspire to defeat global warming

1. TSD in ReptilesHow the physical andthe physiological conspireto defeat global warming Arthur Georges Applied Ecology Research Group University of Canberra

3. Sex versus Temperature

4. Established Results • Dramatic effect – usually 100% of one sex or the other • Only a small range of temperatures (threshold) produces both sexes • TSD is widespread among reptiles

5. European Pond Turtle (France) Threshold = 28°C

6. Temperatures in Natural Nests Temperatures recorded atfour depths over 24hrs

7. American Map Turtles

8. Diel Cycle Daily Temperature Cycle T = R Cos (t) + M where M is the meanand +/-R is the range

9. Diel Cycle Daily Temperature Cycle T = R Cos (t) + M where M is the meanand +/-R is the range

10. Diel Cycle

11. Diel Cycle

12. Linear CTE Model CTE = R.Cos (t’) + M t’ = - sin (t’) p R 2 M – T0

13. Predicting Sex

14. American Map Turtles

16. Development Rate Development Rate increases linearly with time = A(T – T0) where T0 is thedevelopmental zero ds dt

17. Sex vs Temperature

18. Loggerhead Turtles Sex ratios versus Daily range At a fixed mean of 26°C Line = model prediction

19. Loggerhead Turtles Sex ratios versus Daily range At a fixed mean of 26°C Line = model prediction

20. Daily Thermal Regimes Mean temperaturevaries a little –by 0.6°C Daily range variesby up to 3.0 °C CTE variesby about 2.0 °C

21. Thermal Gradients

23. Development in Carettochelys

26. Core Temperature Trace

27. Core Temperature Trace

28. Core Temperature Trace

29. Linear Model

30. Fitting Non-linear Models

31. Sharpe-DeMichelle Model

32. Incubation Period

33. Sex

34. Sex

35. Conclusion • Contrary to previous reports…

36. Conclusion • Global warming may well NOT be the female turtle’s answer to male chauvinism!

38. Single Switch

39. Title? Patterns of oxygen consumption during incubation

40. Linear CTE Model – example CTE = R.Cos (t’) + M t’ = - sin (t’) • Emys orbicularis – France (Pieau, 1982) • T0 = 16.1, Mean = 24.8°C, R = 7.5 °C • t’ = 0.8980 (6 hrs 51 mins) after 14 iterations • CTE = 29.5 °C p R 2 M – T0

41. Refinement #1 • When temperatures drop below the developmental zero each day

42. Yet to be done… • Test the utility of the models in real field situations • Test the Linear CTE Model with Threshold in the laboratory, incorporate the Sharpe-DeMichelle Model • Simplify computation – the WEB • Explore the broader implications for hatchling phenotypes in general • Global warming

43. Double Switch

44. European Pond Turtle (France) Threshold = 28°C

45. Sex versus Temperature