Batagur dhongoka has disappeared from much its former range in the past few decades. Credit: A. K. Panda/WII
Mitochondrial and nuclear DNA analysis of the critically endangered three-striped, roofed turtles (Batagur dhongoka) shows that they still have a moderate level of genetic diversity, despite recent decline and a limited genetic capacity to adapt to environmental changes1.
Once abundant in the Ganga and Brahmaputra basins, B. dhongoka numbers have plummeted by over 80% in the last 50 years. A team of researchers at the Wildlife Institute of India (WII) in Uttarakhand says the genetic data from the study could be used to monitor population status, inform captive breeding of the turtles, and strategically reintroduce turtles into their natural habitats.
The scientists studied two mitochondrial DNA (mtDNA) fragments and microsatellite DNA markers in tissue samples. These came from the Turtle Rescue and Rehabilitation Centre (TRRC) in Sarnath and the Ganga Aqualife Rescue and Rehabilitation Centre (GARRC) in Narora.
Mitochondrial DNA, passed down from mother to offspring, more accurately traces population history, while microsatellite DNA markers — short, repeating sequences of DNA — offer a snapshot of genetic diversity.
Genetic analysis showed that TRRC turtles share a similar genetic ancestry with those from GARRC. The team, led by S. A. Hussain, found low nucleotide and high haplotype diversity in mtDNA (haplotype is a heritable set of DNA variants on a single chromosome).
There were few genetic differences among the turtles, suggesting that they grew in number over the last two thousand years from a small group, a hopeful indication of species recovery, says Ajit Kumar at WII.
