Scientists work to unravel western rattlesnake DNA
When a threatened western rattlesnake shows up on your back doorstep in semi-arid B.C., the last thing on your mind is the unique genetics of the creature. But new research is underway looking into the DNA of isolated pockets of rattlesnakes in the south-central region of the province, and the findings could lead to special conservation management decisions.
“It’s quite an adventure,” said Danielle Schmidt, a master’s student at the Okanagan campus of the University of B.C. “It’s been the coolest experience of my life. I love everything about it.”
Schmidt, interviewed at the North American Congress for Conservation Biology, said rattlesnakes are currently managed as a single population, and occur at various locations, such as Kamloops, Osoyoos, Vernon, Grand Forks and the Fraser Canyon.
The working theory, however, is that highways, persecution, and habitat loss due to agriculture and other human impacts may have contributed to the isolation of specific populations, and that may have an influence on genetics.
It is also possible that some populations have always been isolated, due to geography.
To address the issue, about 840 DNA samples have been obtained from rattlesnakes throughout their B.C. range.
Some are obtained from roadkill, since that is a leading cause of rattlesnake deaths. On occasion, samples wind up being gopher snakes, which can look similar. The public is not being asked to participate due to the risk of receiving a poisonous bite.
“Rattlesnakes, even after they ’re deceased, there is potential if you go to touch them, that they have a reflex,” Schmidt said. “It’s still pretty dangerous to pick a tissue sample if you’re not aware of that.”
In May this year, a man in Texas almost died after he was bitten by a rattlesnake he had just decapitated. He began having seizures, losing his vision and bleeding internally and was eventually airlifted to hospital, The Associated Press reported.
Snakes shed their skin, which can be a convenient, non-invasive way to obtain DNA.
Other options require more caution, including grabbing snakes entering or leaving their hibernacula, areas where they den over winter in groups.
Schmidt said researchers use tongs to put rattlers into an “Ikea laundry basket,” then their heads go into Plexiglas tubes to prevent researchers from being bitten while a DNA sample is obtained from the cloaca, the posterior orifice that serves as the opening for the digestive, reproductive, and urinary tracts.
It is early days in the research, but preliminary results suggest there is, indeed, “genetic differentiation and separation between populations,” including distinction in the Kamloops/Ashcroft population, as well as Vernon. Those around Osoyoos may be mingling with rattlesnakes from Grand Forks and, to the south, in Washington state.
Schmidt is hopeful that the study results will help to raise public awareness for the beleaguered rattlesnake.
“I understand people don’t want rattlesnakes on their back door,” she said. “But they do play a huge role in the ecosystem: they keep rodent populations under control. They’re so much more than just scary snakes.”
The federal Committee on the Status of Endangered Wildlife in Canada reported in 2015 that the western rattlesnake is the only venomous snake native to B.C.
Adults can reach 1.3 metres in length, and sport a triangular head that is noticeably wider than the stout body, and a number of loosely interlocking horny segments at the end of the tail that the snake can vibrate to produce a warning rattle.
The B.C. population of western rattlesnakes “probably exceeds 10,000 adults, but there is much uncertainty about the population size,” the report concluded.
The provincial and federal governments have also contributed to the ongoing DNA research project.
(Rattlesnakes) do play a huge role in the ecosystem: they keep rodent populations under control. They’re so much more than just scary snakes.