Research Highlights

Nature Reports Climate Change
Published online: 10 July 2008 | doi:10.1038/climate.2008.69

Only the lonely

Anna Barnett

Proc. R. Soc. B.doi:10.1098/rspb.2008.0438 (2008)

NICOLA MITCHELL

A rare 'living fossil' reptile will go the way of the dinosaurs if rising temperatures trigger all of its eggs to hatch into male offspring.

Embryos of the tuatara — an arm-length, spiny-crested creature that closely resembles its Mesozoic ancestors — develop as males in warmer underground nests and females in cooler ones. To forecast this New Zealand native's demographic future, Nicola Mitchell of the University of Western Australia and colleagues modelled nest microclimates for the rarest tuatara species, Sphenodon guntheri. Modest seasonal warming of 0.1–0.8 °C by the 2080s would boost the proportion of males slightly, they found. But if air temperatures rise by 4 °C, a possibility under a maximum-warming scenario offered by the New Zealand Climate Office, all hatchlings will be male unless females shift nesting sites or eggs are laid later.

Already wiped out on the main islands of New Zealand by introduced mammals, tuataras survive only on small offshore outposts with little room to move towards the more temperate south. To ensure a supply of females throughout the twenty-first century, the scientists say, conservation workers could artificially shade tuatara nests after the mothers have buried their eggs and left the scene — or relocate the reptiles to cooler areas.