Genetic Forensics Wakes a Dragon
A genetic investigation into the illegal trade of sailfin dragons has unearthed a surprise: a new species of the rainbow-colored lizards that resemble small dinosaurs. The finding highlights just how little is known about these mysterious and threatened animals.
Sailfin lizards (genus Hydrosaurus) look like they were pulled from a child’s coloring book. As the water-loving reptiles mature, their faces, dorsal crests, and saillike tails shift from a drab green and gray to vibrant shades of neon purple, cyan, and harlequin. That’s made them a popular target for an illegal pet trade which—along with destruction of their habitat in the Philippines, eastern Indonesia, and New Guinea—has decimated their numbers. In the wild, only juveniles remain in most populations, says Cameron Siler, the curator of herpetology at the University of Oklahoma, Norman.
To learn more about the enigmatic animals, Siler and his colleagues swept the black markets of Manila, a trade hub, collecting DNA samples from the toenails and scales of 20 sailfin dragons between 2011 and 2012. They then compared these specimens to the genetic material of 80 animals whose origins traced across the sailfins’ four major island habitats: the Philippines, Sulawesi, Halmahera, and New Guinea.
When the researchers determined the evolutionary ties between the lizards based on their DNA, they discovered that the three accepted Hydrosaurus species are actually four. Sailfin lizards from Sulawesi in Indonesia were originally grouped with the species from New Guinea more than 140 years ago, but the genetic survey suggests that Sulawesi dragons are a separate lineage, the team reports in the January issue of Biological Conservation.
The study has solid geographical sampling, and the team’s statistical analysis of two DNA genomes—mitochondrial and nuclear—shows pretty good evidence for the new species, says Bryan Stuart, a curator of herpetology at the North Carolina Museum of Natural Sciences in Raleigh, who was not involved in the work. “We don't very often see forensic studies like this.” Additional specimens from New Guinea are needed to fully confirm the new species, but the findings are convincing, he says.
According to the team’s genetic comparisons, all the smuggled dragons seem to have come from a single location in the Philippines: the Bicol Peninsula on Luzon Island. The area is home to large swaths of sailfin habitat, Siler says, but this could change because very few coastal habitats are protected. Protected regions in the Philippines are mainly concentrated in the mountainous highlands where a high density of primary forest remains, he notes. Although this benefits many species, including several endangered birds, it leaves hydrosaurs and other coastal fauna exposed. Siler and colleagues found that current laws in the Philippines protect less than 10% of existing habitats that are suitable for sailfin dragons. The native Philippine species, Hydrosaurus pustulatus, is listed as a vulnerable species by the International Union for Conservation of Nature.
The genetic forensics used in the current study could aid conservation efforts for reptiles and amphibians across Southeast Asia, especially turtles, which Stuart says are poached and smuggled from every country in Asia. When large shipments are caught, officials often face the dilemma of what to do with animals confiscated far from their home range. “You don't want to start mixing genetic lineages in the wild or captivity that might not normally breed with one another,” he says. This study provides a blueprint for responsibly incorporating them into captive breeding programs, he says, or very carefully reintroducing them back to their area of origin.