Ancient woolly rhinos killed are not people, and climate change: this is the conclusion reached by the team of researchers analyzed the genomes of 14 ancient giants. They found that up to the extinction, the number and genetic diversity of woolly rhinoceros remained stable, which means that extinction of species has occurred very quickly. In addition, at the time of extinction coincides not with the arrival of the first people in Eastern Siberia, and with the sharp warming that began with 14.6 thousand years ago. Details of the study are published in the article for the journal Current Biology.
Only a few tens of thousands of years ago the Earth was inhabited by many species of large herbivores and predators, most of which disappeared in the late Pleistocene. Scientists attribute the extinction of the megafauna because it was hunted human ancestors, however, individual species could be affected by other factors — for example, climate change.
A team of researchers led by Adanai Lord (Edana Lord) of Stockholm University decided to look into the reasons for the disappearance of woolly rhinoceros (Coelodonta antiquitatis) is one of the most famous megafauna. Once this species was widely distributed throughout Northern Eurasia, but died about fourteen thousand years ago.
Scientists have identified genetic material from the remnants of rhinoceros, discovered in Eastern Siberia and dated 14-50 thousands of years. With the help of modern technology they were able to restore one complete nuclear and 14 mitochondrial genomes.
Analysis of mitochondrial genome revealed woolly rhinoceros 13 haplogroups. They belonged to two evolutionary clades that diverged about 205 thousand years ago. 154 thousands of years ago from the first clade separated another line that is unique to Wrangel island. High diversity of mitochondrial genomes remained until the extinction of the species — indeed, 86-22 thousands of years ago within both the treasure, there was a rapid diversification.
On the basis of genetic data, researchers have constructed a demographic model for the population of woolly rhinoceros, according to which in the period 110-14 thousand years ago, the species population is not reduced. On the contrary, it some time grew, and then remained stable. The increase in population could be linked to climate change, through which about 29 thousand years ago in Eastern Siberia was formed more suitable conditions for cold-water rhinoceros.
Judging from the nuclear genome of an individual, who lived 18,5 thousand years ago, at this time, the woolly rhinos were still widespread in Eastern Siberia. The appearance of people who inhabited the region about 31.6 thousand years ago, did not impact their numbers — at least the genome has not preserved the traces of the decline of populations and inbreeding. This means that humans and woolly rhinoceros co-existed for at least 13 thousand years and the main factor that led to the final extinction of the ancient giants, was not hunting.
The authors suggest that the disappearance of this species can be blamed on abrupt climate change. According to genetic data, the woolly Rhino became extinct very quickly, and it happened from 18.5 to 14 thousand years ago. This will coincide with a sharp belling-allerersten warming, which started around 14.6 thousand years ago. Maybe it was deprived of the woolly rhinoceros of suitable habitat.
Additionally, scientists have been searching for the genes that allowed woolly rhinos to adapt to the cold climate. To do this, they compared the nuclear genome of the extinct species with the genome sumatrensis rhinoceros (Dicerorhinus sumatrensis), which is considered to be his closest surviving relative.
19556 comparing genes of two species, the scientists found in the genome of the woolly rhinoceros 1524 nonsynonymous substitutions. Among them were genetic variants associated with cellular processes, metabolism and reproduction. Unlike mammoths (Mammuthus primigenius), woolly rhinoceros did not become particularly genes associated with fat accumulation and changes in circadian rhythms. However, some adaptations to cold in two species were common — for example, specialized receptor gene TRPA1, are involved in the perception of temperature.
At the other end of the Earth, in Australia, too, once inhabited by gigantic herbivores, and predators. Most scientists are inclined to the hypothesis that they exterminated people. However, new data indicatethat at least in some parts of the continent’s megafauna coexisted with humans for 20 thousand years. Perhaps the ancient giants killed is not hunting, and the gradual desiccation of the climate.
Sergey Knee High