Global warming is bad news for New Zealand's famous living fossil because temperature sets the sex of tuatara hatchlings.
"When we incubate the eggs in the lab, there is just 1C difference between what produces all females and what produces all males," says Victoria University tuatara expert Dr Nicky Nelson.
"Global warming
may upset the balance of the sexes, so it has real implications for the survival of the species."
Eggs incubated at 21C have a 50 per cent chance of hatching into males or females. But as temperature increases, incubation time drops and the chance of males emerging from the eggs increases.
The cold-blooded tuatara cannot control the temperature of the six to 10 eggs they lay every fourth year. Fewer than half the eggs and hatchlings survive, but adults have a high survival rate and can live longer than 100 years.
They inhabit about 30 coastal islands from the Poor Knights to the Bay of Plenty, and seven islands in Cook Strait.
Dr Nelson completed her PhD on tuatara last year and is using a San Diego Zoo millennium fellowship for a three to five-year study of the effects of global warming on the sex of unhatched eggs.
- NZPA
nzherald.co.nz/environment
