Figure 1.

Realistic rates of warming and cooling were used to estimate the temperatures that reduce the survival of lizard embryos. (a) Four thermal cycles used to estimate the effect of acute warming. (b) The proportion of embryos that survived daily cycles of temperature depended on the maximal temperature of the cycle (35–42°C). (c) The survival of embryos after cooling depended on the minimal temperature (top circles, survived to hatching; bottom circles, died before hatching; size of circles represents the number of embryos). (d) Empirical data were used to construct a theoretical relationship between body temperature and the rate of embryonic survival. (Online version in colour.)