RT Journal Article
SR Electronic
T1 Evidence of long-term purging of mutation load in killer whale genomes
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2021.08.21.457186
DO 10.1101/2021.08.21.457186
A1 Andrew D. Foote
A1 M. Thomas P. Gilbert
A1 Shyam Gopalakrishnan
A1 Marie Louis
A1 Michael D. Martin
A1 Phillip A. Morin
A1 Milaja Nykänen
A1 Camilla Hjorth Scharff-Olsen
A1 Laurent Excoffier
YR 2021
UL http://biorxiv.org/content/early/2021/08/21/2021.08.21.457186.1.abstract
AB Genomes of high latitude killer whales harbour signatures of post-glacial founding and expansion. Here, we investigate whether reduced efficacy of selection increased mutation load in founder populations, 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 the most significant outliers are high latitude North Atlantic genomes, which have accumulated significantly fewer non-synonymous mutations than all other populations. Comparisons with the genome of a 7.5-Kyr-old North Atlantic killer whale, inferred to be closely related to the population directly ancestral to present-day Icelandic and Norwegian populations, calibrates the timing of the action of selection on non-synonymous mutations predominantly to the mid-late 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 overdominance. Taken together, our findings are consistent with purging of recessive non-synonymous mutations exposed to selection in founder-associated homozygous genotypes.Competing Interest StatementThe authors have declared no competing interest.