PLOS Science Wednesday: Hi reddit, my name is Rebekah Rogers and I found that, before extinction, two different species of woolly mammoths had bad genetic mutations, which likely didn't help their survival -- Ask Me Anything!

Abstract

Hi Reddit, My name is Rebekah L. Rogers and I am an Assistant Professor in the Department of Bioinformatics at UNC Charlotte. My research focuses on genome structure changes and new gene formation. I recently published a study titled “Excess of genomic defects in a woolly mammoth on Wrangel Island” with Montgomery Slatkin. We reanalyzed genome sequences for two woolly mammoths. One specimen came from Siberia at a time when mammoths were happy and healthy. The other comes from a small population that existed on Wrangel Island until 3700 years ago, another 600 years after all mainland mammoths had gone extinct. We found that bad mutations were accumulating in woolly mammoth genomes just before they went extinct. The accumulation of bad mutations is consistent with mathematical theories predicting that natural selection becomes inefficient in small populations. Under these circumstances, bad mutations could accumulate in genomes that normally would be weeded out by competition. The mammoth from Wrangel Island had 50% more of its genes broken compared with the mainland mammoth from much earlier. Several different types of bad mutations had accumulated— large deletions in the DNA, retrogenes (which reflect the action of selfish virus-like DNA sequences), and single letters that would cause genes to terminate early. Many of the broken genes are urinary proteins and the olfactory receptors that detect them — genes important for social signaling. We also discovered that the mammoth from the island had mutations that would give him a shiny satin coat. These results may be important for conservation. They suggest that other very small populations of endangered species might undergo the same type of mutational meltdown. In our mammoths, we found that it required many generations to see a signal as strong as what we observed in the Wrangel Island genome. The sooner we can intervene to bring endangered species back to normal levels, the better off their genomes will be. There are many factors that influence extinction. Climate change, habitat destruction, and hunting were all very important for the mammoths’ demise. Still, these bad mutations certainly did not help them as the struggled to adapt on the island. Listen to the 60 second Science podcast on our work. I will be answering your questions at 1pm ET. Ask me Anything! Don’t forget to follow me on Twitter @evolscientist or elsewhere on reddit as rlrogers. Alright! 1pm ET! Ready to go! Ok, thanks for all the fun questions!! I had a great time! Now it's back to the lab to collect fruit flies!