Endangered Turtles and the Genetics of their Sexual Behavior

NY Times & BBC. At the University of East Anglia, UK, Dr.David Richardson studies the elusive Hawksbill seaturtle and its mating habits. The female was found to take sperm from one male and fertilize multiple generations with it .This behavior of hoarding sperm is found in animals including reptiles, birds and various tortoises and terrapins. The females can store the sperm for an elongated period of time, thus the possibility of egg clutches being fertilized by multiple fathers. Dr.Richardson tested the DNA of Hawksbill hatchlings during the breeding season on Cousine Island. During their long 75-day mating seasons, the majority of their egg clutches were fathered by a single male. The males in the study did not fertilize more than one female. It came to a shock to the researchers because genetic monogamy is not nearly as common as polygamy.

These turtles tend to mate far away from shore where they search for food on the Western Indian Ocean. The study itself found a vast amount of males for females to mate with and not just a few individuals close to shore, as the scientific community once thought. This is good news since a higher degree of genetic variation ensures the future of its species. A high degree of variation means the population can bounce back from strange diseases or changes in the environment. However, this genetic superiority cannot protect them from human predators that hunt them for their shells. This endangered species are found in tropical waters around the world to lay approximately five clutches of eggs in their 75 day mating season. The DNA testing samples from the hatchlings gave researchers critical information to conclude that mating occurs far out at sea and that their numbers are steadily rising. Coupled with their decoded variability, the Hawksbill turtle is much better off than once thought.