Woolly mammoths were one of the most common herbivores in Siberia, Northern America and Beringia until warmer climates and human hunters wiped out the mainland mammoth 10,000 years ago.
Isolated herds, however, managed to hang around for another 6,000 years scattered across Serbian islands. These isolated island mammoths mutated, according to new findings, developing a rather uncomfortable evolutionary denouement. One that should serve as a warning to conservationists working to rescue endangered species, and to scientists attempting to resurrect the mammoth species.
The new study from PLOS Genetics by Rebekah Rogers and Montgomery Slatkin of the University of California, Berkeley compares the genomes of two unearthed Woolly Mammoths- one from mainland Siberia 45,000 years ago and one 4,300 years old from Wrangel Island, a barren rock, north of Siberia known as the “Last Mammoth Refuge”. Both Slatkin and Rodgers describe the woolly mammoth’s final years as a “genetic meltdown.” The woolly giants were so wrought with destructive mutations that they could no longer mate or smell.
The weird genome mutations turned their famously shaggy coat translucent and satin-like. The mammoths also lost their sense of smell and walked around with irritated stomachs. The worst of their mutations changed the proteins in the giant’s urine- ruining the beast’s sex life and social status.
The findings align with a mathematical model theory- when an animal population decreases, it can experience a genomic deterioration, so bad mutations that would normally be weeded out by natural selection, stick, simply because there are fewer genetic variants from which to select. Rebekah Roger explains;
This study was very interesting because it let us look at a snapshot of 'before' and 'after' a change in population size within a single species, in the Wrangel Island mammoth we see a massive excess of what appear to be bad mutations. It’s difficult to catch a population in the process of going extinct, but this study finally made it possible, thanks to advances in DNA sequencing.
The mutation of the island mammoths should serve as a warning for conservationists. Preserving a small group of isolated animals is not enough to deter inbreeding and genomic mutation. Biologist Love Dalén from the Swedish Museum of Natural History continues, “The finding that genomic deletions may increase in declining populations is something that has been overlooked in conservation biology. If this is a general pattern in other species, it will constitute an additive threat to the genetic health of threatened species.”
Essentially, the longer a species remains small in population, the more at risk it is of mutation. Bad news for the hundreds of species added to the endangered list this year.
Geneticist Dr George Church and his team at Harvard exploring the resurrection or “de-extinction” of the woolly mammoth need to consider the eventual mutation and deterioration of the species.
As Love Dalen so eloquently explains:
I don't know if they are planning to use the Wrangel genome, but if so, they could be in for some surprises—possibly satin-coloured surprises with gastric irritation.