KEY POINTS:
Dominant tuatara males are ruling their own roost but not doing much for the genetic diversity of their species, says Victoria University researcher.
PhD student Jennifer Moore, who has studied the mating system of tuatara for four years, found that the New Zealand reptile, of which there are only about 70,000, was also a bit of a homebody and didn't like to move about much, even when its habitat was disrupted.
She said that, as with other reptiles, tuatara mating was dominated by a small proportion of large males, which could decrease the genetic diversity of a population.
"Annually, male reproduction is highly skewed in the wild and in captivity," she said.
"More than 80 per cent of offspring from a captive population on Little Barrier Island were sired by one male and multiple paternity was found in approximately 18 per cent of these clutches.
"This has led to reduced genetic variation in the recovering Little Barrier Island population."
She also found that these long-lived reptiles have a stable social structure that can be influenced by human-induced habitat modification.
Tuatara genes showed the population changes appeared to be driven by changes to habitat in the past and a sedentary lifestyle in the absence of dispersal or migration.
That was illustrated on Stephens Island in the Marlborough Sounds where land was cleared for pasture, affecting tuatara populations.
Ms Moore's results should allow management and captive breeding programmes to maximise genetic diversity and help select individuals to found new translocated populations.
Conservation programmes could increase the genetic diversity of a small population by removing the dominant male, allowing other smaller males to mate more, she said.
Ms Moore's next research project will be in Alaska studying toads.
- NZPA
