Evidence of long-term purging of mutation burden in killer whale Orcinus orca genomes

Details

• Journal Title:
  Heredity
• Personal Author:
  Foote, Andrew D. ; Gilbert, M. Thomas P. ; Shyam Gopalakrishnan ; Louis, Marie ; Martin, Michael D. ; Morin, Phillip A. ; Nykänen, Milaja ; Scharff-Olsen, Camilla Hjorth ; Excoffier, Laurent
• NOAA Program & Office:
  NMFS (National Marine Fisheries Service) ; SWFSC (Southwest Fisheries Science Center)
• Description:
  Genomes of high latitude killer whales (Orcinus orca) harbour signatures of post-glacial founding and expansion. Here, we investigate whether reduced efficacy of selection increased the predicted mutation burden in founder populations with low Ne, or whether recessive deleterious mutations exposed to selection in homozygous genotypes were purged. Comparing the accumulation of synonymous and non-synonymous mutations across pairs of globally sampled genomes reveals that high latitude North Atlantic genomes have accumulated proportionally fewer non-synonymous mutations than other populations. The genome of a 7.5-Kyr-old North Atlantic killer whale, inferred to be closely related to the direct ancestors of the present-day Icelandic and Norwegian populations, was used to calibrate the timing of the action of selection on non-synonymous mutations predominantly to the Holocene. Non-synonymous mutations purged in modern Norwegian killer whale genomes are found as globally shared standing variation in heterozygote genotypes more often than expected, suggesting associative- or pseudo-overdominance. Taken together, our findings are consistent with purging of recessive non-synonymous mutations exposed to selection in founder-associated homozygous genotypes.
• Keywords:
  • Orcinus orca
• Source:
  Heredity 134, 671-679 (2025)
• DOI:
  https://doi.org/10.1038/s41437-025-00806-5
• Format:
  PDF
• Document Type:
  Journal Article
• Rights Information:
  Accepted Manuscript
• Compliance:
  Submitted
• Download URL:
  https://repository.library.noaa.gov/view/noaa/76625/noaa_76625_DS1.pdf
• File Type:
  [PDF - 2.03 MB]
• Collection(s):
  National Marine Fisheries Service (NMFS)
• Main Document Checksum:
  urn:sha-512:079f243f4312dc2be8d69d10d21274000dd7c67c3414e0188553d685f53a321bbd0e23d8fbd539a65df79f8e895d60b5f1a2d208f8c6cd71bbf2b00abe2b1c73