It can be difficult to live on the Tibetan Plateau. The air is so thin that it takes a few steps to breathe. The Sun is so intense that it burns the skin. The herpetologist at the Chinese Academy of Sciences studies has been studying snakes for millions of years. The Tibetan hot-spring snake keeps from freezing to death by hanging around the region's pools.
Li and others are getting a better idea of how the snake has adapted to its environment. His team has identified genes that may help the snake find water that is warm enough to survive the Sun and low oxygen. The evolutionary history of the snake has been reconstructed by Li and his team in order to guide efforts to save the reptile.
A herpetologist at the Field Museum says that this is an extreme place for snakes to live. The work shows how flexible snakes are. Alex Pyron is a herpetologist at George Washington University. It's not so fast, saysThermophis.
T. baileyi is the only one of the more than 100 species of snakes that live in the Tibetan region. There are two other hot-spring snakes that live at lower altitudes and are not dependent on the hot springs. Other snakes, including a pit viper, exist even higher, but the key difference is that they are mostly found at lower altitudes.
The outside temperature is an important factor in the evolution of snakes. The snakes are able to survive below 20C because they are near the edges of the pools that reach 40C. The warmth causes challenges of its own. The warmth of high altitude makes it difficult for hot snakes to get enough Oxygen.
Li led teams to capture snakes and collect blood and tissue from the tip of their tails for study. The researchers could not see a snake for days if the Sun was out. Their initial, incomplete genome, published in 2018, revealed changes in genes that enhance breathing, make red blood cells more efficient, and make the heart beat more powerfully. He and his colleagues reported that some of the same genes have changed in species that live at high altitudes.
Modifications to genes that help repair DNA damaged by ultraviolet radiation were identified in the study. There are at least two genes that are altered in a lizard living on the Tibetan Plateau and other high-altitude animals, according to a new study. Todd Castoe is an evolutionary biologist at the University of Texas, Arlington.
The snakes cope with the challenge of finding bathing spots that are not too hot by using a more complete genome. The team compared the genes involved in temperature sense in hot-spring snakes and other organisms. The hot-spring and heat-sensitive snakes have a variation in the TRPA1 genes.
A cascade of signals can be sent to the brain or other parts of the snake's body when an ion channel is opened and closed. Changing to TRPA1 lowers the temperature of the channel and improves the snakes ability to detect prey. In hot-spring snakes, different changes to theprotein ensure the channel opens up very quickly and completely.
Li thinks the changes may help the snake orient towards warmth. In behavioral experiments reported in the new paper, his group found that hot-spring snakes preferred the warm rock more often than did two other snake species that don't live at high altitudes.
Castoe points out that the snakes are walking between not boiling and not freezing to death. The threat of sweltering seems to have shaped other genes.
The snakes have a mark on their genes from climate history. The Tibetan hot-spring snakes were collected in 15 places. Three distinct populations that are roughly the same in size were found to have different genes. The pattern is the work of past ice ages according to Li and colleagues. The westernmost group split off from the rest of the species during a major ice age between half and three-quarters of a million years ago, and then the central and eastern populations were divided 300,000 years ago because of a new barrier of cold. They got through the ice ages thanks to the thermal springs.
Each group was able to adapt to the isolation. Several genes for processing selenium and for metabolizing sulfur have evolved rapidly in the western group, which may be related to the chemistry of hot springs there.
Frank Burbrink, a herpetologist at the American Museum of Natural History, says that the three groups are unique enough to be considered a species. They aren't sure they're that different. Burbrink thinks that they need to be separate.
Populations are decreasing. The survival of Tibetan hot-Spring snakes has been affected by human activities. Construction has destroyed the dens where these animals spend their winters. Wetlands in other places have been ruined due to development. Artificial snake dens, restoration of wetlands and fencing people out of sensitive spots are all planned to be built in May of 2020.
The snakes are adapted to nature but not to the pressures of humans.
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