Feb. 7 (UPI) -- By the end of the last ice age, some 10,000 years ago, most of Earth's mammoths were gone. However, a few small, isolated populations pressed on.
The mammoths living on Wrangel Island in the Arctic Ocean were one of those isolated populations. The were likely some of the last mammoths on Earth. They died out 3,700 years ago.
New research, published this week in the journal Genome Biology and Evolution, suggests mutations accumulated in the genome of the Wrangel Island mammoth population prevented their genes from functioning properly.
Previous studies have shown that the mammoths living Wrangel Island suffered from a variety of genetic defects. As isolated populations decline, interbreeding and a lack of genetic diversity prevent species from purging their genomes of mutations.
The latest research showed that many of these mutations were disruptive.
"The key innovation of our paper is that we actually resurrect Wrangel Island mammoth genes to test whether their mutations actually were damaging -- most mutations don't actually do anything," lead study author Vincent Lynch, an evolutionary biologist at the University at Buffalo, said in a news release. "Beyond suggesting that the last mammoths were probably an unhealthy population, it's a cautionary tale for living species threatened with extinction: If their populations stay small, they too may accumulate deleterious mutations that can contribute to their extinction."
In California, studies have shown that mountain lions hemmed in by highways and other kinds of human development are suffering from low levels of genetic diversity.
For the new study, scientists compared sequenced DNA recovered from the remains of a Wrangel Island mammoth with the genomes of a pair of more ancient mammoths from larger, more diverse populations. Researchers also compared the mutation-rich mammoth genome with the genomes of three Asian elephants.
The analysis revealed genetic mutations unique to the Wrangel Island mammoth. In the lab, scientists synthesized the DNA mutations and inserted them into cells in petri dishes. Tests showed the proteins expressed by the mutated genes failed to interacted normally with other genes and molecules.
"We know how the genes responsible for our ability to detect scents work," Lynch said. "So we can resurrect the mammoth version, make cells in culture produce the mammoth gene, and then test whether the protein functions normally in cells. If it doesn't -- and it didn't -- we can infer that it probably means that Wrangel Island mammoths were unable to smell the flowers that they ate."
Authors of the new study suggest the latest findings complement the results of a 2017 study that showed gene mutations impacted the olfactory receptors of Wrangel Island mammoth, as well as their ability to produce of certain urinary proteins -- mutations that may have impacted mammoths' social status and mate choice.