Researchers have gotten their first look at the complete genome of the wooly mammoth and it provides important clues about the decline and eventual extinction of the animals.
An international team actually got a look at two mammoth genome sequences from specimens born 40,000 years apart. The first was a representative of the last known mammoth population from Russia’s Wrangel Island. It lived 4,300 years ago, just a few hundred years before the species became extinct. The second came from northeastern Siberia and lived 44,800 years ago.
In a report in the journal Current Biology the researchers report that the younger of the two specimens showed significantly less genetic variation than it’s older Siberian ancestor. Large portions of its DNA showed no variation at all, which is a sign of a small population in which inbreeding becomes the norm.
“We found that the genome from one of the world’s last mammoths displayed low genetic variation and a signature consistent with inbreeding, likely due to the small number of mammoths that managed to survive on Wrangel Island during the last 5,000 years of the species’ existence,” says Love Dalén of the Swedish Museum of Natural History in a statement.
Sequencing genomes from long dead animals is very difficult and frequently impossible. The DNA is usually damaged and contaminated by DNA from other organisms such as microbes. However, partially due to the cold conditions in which they lived, the researchers were able to find two samples well preserved enough for accurate sequencing.
By analyzing the full genome the researchers were able to look back in time to study the populations the animals came from. Based on their examination, the researchers report that in the Middle or Early Pleistocene, about 250,000 years ago, wooly mammoth populations suffered a blow which decreased genetic diversity.
At the end of the last glaciation, the mammoth population suffered an even more severe decline from which it never recovered.
“Only by generating high-quality genomes could we discover population-size changes far back in time, revealing two significant population crashes in the mammoth’s history,” said Eleftheria Palkopoulou of the Swedish Museum of Natural History, lead author of the new paper.
The researchers from the United States, Canada, Sweden and Russia say that they plan to continue sequencing mammoth genomes in the hope of painting a more complete picture of the animal’s evolution and decline.
“Sequencing the genomes from extinct animals will not only help us better understand the biology and history of these species, but can also provide important information on how and why species become extinct in general,” Dalén says.
The study comes on the heels of a report last month from a team at Harvard that has successfully copied genes from a wooly mammoth onto the genome of an asian elephant.
Although they are still in the very early stages, that team hopes to one day have the capability of creating an actual, living, breathing mammoth. The, still controversial, concept is called de-extinction and could someday allow scientists to bring back extinct species and bolster the numbers of extremely endangered species.
