A report in “Nature” suggests that Woolly Mammoths had bad genes towards the end of their days that may have stripped them of their sense of smell and turned their hairy coats translucent. The study involved with uncovering this may give us a glimpse into how genomes change as a species dies out and begins to enter into extinction.
The Woolly Mammoths had mostly died out around 4 kya save for about 300 remaining on Wrangel Island off the coast of Siberia. Researchers compared the complete genome of a mainland mammoth that lived 45 kya to one from Wrangel Island who lived about 4.3 kya and what they found was that the Wrangel specimen had a lot of excessive bad mutations! For one, the Wrangel specimen’s genome was riddled with gene deletions and an abundance of “stop codons” that tell a cell when to stop transcribing a section of DNA.
Some of the resulting changes would have been visible to the naked eye such as changes in the behavior of this animal and changes in its appearance. The researchers also found that changes in smell and urinary protein genes likely important to mating behaviors and maybe signifying social status were shut down in the Wrangel Island specimen by the gene mutations. Researchers also believe that the later Woolly Mammoths would have had a satin-like coat that was shiny and translucent although the coat would have still had its color.
I would say that the reduced sense of smell and the reduced urinary protein which in modern elephants are very important for eliciting breeding behaviors and signaling social status most likely led to reduced breeding and, thus, reduced offspring which only helped the process of extinction of these creatures along further.
Researchers also found that bad mutations that are normally weeded out were not weeded out but remained. In short, the Woolly Mammoth was in a sort of “genetic meltdown” prior to its extinction. Researchers think that these genetic changes took place in the Wrangel Island population after the mainland population had been wiped out.
This study and its findings may help us understand current populations being threatened by extinction. When it comes to extinction there are MANY factors at play not just one. Climate change, human hunting, and other factors all contribute to a species going extinct and now we know that genetics plays a key role too.
So in short as a species enters into extinction reproduction is reduced and likely a break down in the social order. DNA mutations that are normally weeded out in a population and not weeded out but left in the genome and this causes a range of problems for the species. Now that we know what to look for in endangered species this results of this study will be helpful. And, additionally, now we know what to look for in our own species should we face our own extinction.