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!