Rare turtle mysteries

A DNA study has begun to unravel the mysterious mating habits of an endangered sea turtle.

Unlike in many other species, the females normally mate with just one male

Scientists hope the research will aid conservation efforts to protect the hawksbill turtle, a victim of the tortoiseshell trade.

The findings show that female turtles store sperm for up to 75 days after mating before laying multiple beach nests.

Hawksbill turtles are also mainly monogamous and tend to stay with one partner throughout the mating season.

Until now, little has been known about the breeding habits of the turtles, which often live far out at sea.

Lead researcher David Richardson, from the University of East Anglia, said: “We now know much more about the mating system of this critically endangered species.

“By looking at DNA samples from female turtles and their offspring, we can identify and count the number of breeding males involved. This would otherwise be impossible from observation alone because they live and mate in the water, often far out to sea.

“We now know that female turtles mate at the beginning of the season – probably before migrating to the nesting beaches. They then store sperm from that mating to use over the next couple of months when laying multiple nests.

“Our research also shows that, unlike in many other species, the females normally mate with just one male, they rarely re-mate within a season and they do not seem to be selecting specific ‘better quality’ males to mate with.”

Scientists said an important aspect of the research, reported in the journal Molecular Ecology, is that it provides an idea of how genetically viable the turtle population is.

Richardson added: “The good news is that each female is pairing up with a different male – which suggests that there are plenty of males out there.

“This may be why we still see high levels of genetic variation in the population, which is crucial for its long-term survival.”