Scientists have named a species of animal that is dying for millions of years

© Photo : Tom UhlmanНосорог of Ipoh whose DNA decoded scientistsScientists have named a species of animal that is dying for millions of years© Photo : Tom Uhlman

On the island of Sumatra, lives a unique population of rhinos, whose numbers began to decline about a million years ago and never recovered for all this time, say scientists in an article published in the journal Current Biology.

«Our analysis of the genome indicates that the entire Pleistocene was an extremely difficult time for the populations of rhinos in Sumatra. When the sea levels rose and the modern Sunda Islands were isolated from the Asian continent, the number of rhinos has decreased dramatically and never recovered,» says Herman Mays (Herman Mays) from Marshall University in Huntington (USA).

The island of Sumatra, and some parts of the Malay Peninsula and Borneo, it inhabits a very unusual species of rhinoceros — Dicerorhinus sumatrensis, the hallmark of which is that their skin is covered with thick hair, like the famous woolly rhinos of the ice age. In the past, Sumatran rhinos inhabited the entire territory of Southeast Asia, but today their number was reduced to a critically low figure of about two hundred individuals.

The main reason for the reduction in their numbers in recent years, as environmentalists say, is poaching – Rhino horn is one of the most expensive components of traditional Chinese medicines, which even the most stringent bans do not stop hunters from killing rare animals of the world. Additional problem creates the fact that these rhinos almost never breed in captivity, leading scientists to think even about their cloning.

Mace and his colleagues found that these animals began to die out not recently, but nearly a million years ago, first deciphering and studying the genome sumatrensis Rhino. The donor genetic material was made by a male named Ipuh, who died in the zoo of the city of Cincinnati about four years ago.

Comparing halves of his DNA with each other and with similar sites in the genomes of other rhinos, biologists have found when Dicerorhinus sumatrensis separated from the common tree of the evolution of these ungulates, as changing the size of their populations over time, and how many harmful mutations in their genes contain.

These observations showed that Sumatran rhinos are very degenerate animals. The level of genetic diversity at a record low for the wild animals – the number of equal sections in both halves of their DNA they can compete with thoroughbred horses and other domestic animals, which the breeders are constantly crossing between them.

The reason is simple: about a million years ago the number of these rhinos was relatively large, about 60 thousand individuals. Approximately 700-800 thousand years ago there was a cataclysm, in which that number fell about 5-6 times, with the result that Dicerorhinus sumatrensis has set foot on the road to extinction, where they have been going on for a million years.

It appears that their number is slowly but steadily decreased throughout this time, down to the level of about 10 thousand individuals by the time of the latest occurrence of the glaciers that occurred 35-25 thousand years ago, and again fell to the level of 700 individuals after the last ice retreated and sea level rose about 15 thousand years ago.

Like the life story of Dicerorhinus sumatrensis, as the researchers note, suggests that these animals are extremely vulnerable to the impact of climate change and that environmentalists have to take really serious measures to keep their population from complete collapse.

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