PgmNr P2067: Genomic disintegration in woolly mammoths on Wrangel island.

Authors:
Rebekah L. Rogers; Montgomery W. Slatkin


Institutes
University of California, Berkeley, Berkeley, CA.


Abstract:

   Woolly mammoths (Mammuthus primigenius) populated Siberia, Beringea, and North America during the Pleistocene and early Holocene.  Recent breakthroughs in ancient DNA sequencing have allowed for complete genome sequencing for two specimens of woolly mammoths (data from Palkopoulou et al. 2015).  One mammoth specimen comes from mainland populations ~40,000 years ago when mammoth populations were robust.   The second, a  4300 yr old specimen, is derived from an isolated population on Wrangel island where mammoths formed an isolated population with an effective population size 50-fold smaller than previous populations.  These extreme differences in effective population size offer a rare opportunity to test nearly neutral models of genome architecture evolution within a single species.   Using these previously published mammoth sequences, we identify deletions, retrogenes, and non-functionalizing point mutations in the genomes of these two specimens. In the Wrangel island mammoth, we identify a larger number of deletions, a larger proportion of deletions affecting gene sequences, and an increased number of premature stop codons.  We also identify more retrogenes, consistent with elevated retroelement activity.  This accumulation of detrimental mutations is consistent with genomic meltdown in response to low effective population size in the dwindling mammoth populations on Wrangel island, consistent with nearly-neutral theory.