While there has been some talk of bringing the wooly mammoth back to life à la Jurassic Park, it turns out that should such a project be undertaken, scientists would need to be careful with the genetic material they start with. It turns out that just before they went extinct, the massive herbivores had what new research is calling a "genomic meltdown."
In 2015, a group of researchers from a variety of universities published a study in which they extracted DNA from the molar tooth of a mammoth from Wrangle Island in the Arctic Ocean that was about 4,300 years old, and from the soft tissue of a juvenile mammoth from Siberia that dated to about 44,800 years ago. In comparing those samples, the researchers determined that the more recent animals, who were on decline as a species, had higher levels of genetic damage and less genetic variation than the older beasts. Now, researchers at UC Berkeley have taken that work further, identifying specific mutations on the Wrangle Island specimens.
They say that the mammoths that were closer to extinction had genetic abnormalities that would have led them to lack many olfactory receptors and that they lacked several urinary proteins that would be involved in broadcasting their social status and helping them choose mates. "The genome also revealed that the island mammoth had specific mutations that likely created an unusual translucent satin coat," says a UC Berkeley report on the study. The Wrangle Island mammoths lived in a group of about 300 and were some of the last of the species to survive on Earth.
"There is a long history of theoretical work about how genomes might change in small populations," said Rebekah Rogers, who led the work as a postdoctoral scholar at Berkeley. "Here we got a rare chance to look at snapshots of genomes 'before' and 'after' a population decline in a single species. The results we found were consistent with this theory that had been discussed for decades."
The theory about which she is speaking says that as population sizes decrease, genes deteriorate due to the inbreeding brought about by lack of species members. One cautionary tale the research tells is that conservationists looking to save species from extinction might need more than a small population to achieve their goal.
A warming climate and human hunting led to the extinction of the mammoths approximately 4,300 years ago.
The new research has been published in the journal PLOS Genetics.
Source: Berkeley News
