Extinction probability for tuatara on North Brother Island.

<p>Viability is assessed by the percentage of simulated populations predicted to remain after 2000 years (50–64 tuatara generations). Population extinction occurs when only one sex remains. A) The relationship between decreases in adult survival and increases in the male-bias of hatchling sex ratios. B) The sensitivity of percentage changes in hatchling sex ratio and adult survival. Data on changes in hatchling sex ratio are shown at a constant 95% adult survival and changes in adult survival are shown at a constant 65% male-biased hatchling sex ratio. C) The effect on viability with reductions in adult female survival compared to males, using a constant equal sex ratio of hatchlings.