Maintenance of quantitative genetic variation in regions of restricted recombination via associative overdominance
- 1University of British Columbia
Abstract
Mutation-selection balance is the most plausible general mechanism for the maintenance of additive genetic variance (VA) for quantitative traits in natural populations. It is well established that the genetic variants affecting traits (QTLs) are widely distributed across species' genomes. At the same time, unconditionally deleterious mutations are also expected to be common, with those with the largest fitness effects tending to be strongly recessive. Many genomes possess regions of restricted recombination that could result in tight linkage between largely recessive deleterious alleles, conditions which can lead to elevated heterozygosity via associative overdominance (AOD). Here we show that weakly selected QTLs linked to genomic regions exhibiting AOD can elevate VA above what is expected in the absence of unconditionally deleterious mutations. Selection on traits when VA is maintained by AOD, however, may expose recessive deleterious alleles as homozygotes, reducing fitness. Thus, while AOD may contribute to the maintenance of VA, variation maintained in this way may not be readily accessible by natural or artificial selection.
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BibTeX
@misc{zhao2026maintenance,
title = {{Maintenance of quantitative genetic variation in regions of restricted recombination via associative overdominance}},
author = {Y. Zhao and C. Lee and P. Johri and B. Charlesworth and T. R. Booker},
howpublished = {bioRxiv},
year = {2026},
month = sep,
doi = {10.64898/2026.09.20.752755},
url = {https://www.biorxiv.org/content/10.64898/2026.09.20.752755v1},
note = {CC BY-NC},
}
RIS
TY - UNPB
TI - Maintenance of quantitative genetic variation in regions of restricted recombination via associative overdominance
AU - Y. Zhao
AU - C. Lee
AU - P. Johri
AU - B. Charlesworth
AU - T. R. Booker
PY - 2026
DA - 2026/09/20
PB - bioRxiv
DO - 10.64898/2026.09.20.752755
UR - https://www.biorxiv.org/content/10.64898/2026.09.20.752755v1
AB - Mutation-selection balance is the most plausible general mechanism for the maintenance of additive genetic variance (VA) for quantitative traits in natural populations. It is well established that the genetic variants affecting traits (QTLs) are widely distributed across species' genomes. At the same time, unconditionally deleterious mutations are also expected to be common, with those with the largest fitness effects tending to be strongly recessive. Many genomes possess regions of restricted recombination that could result in tight linkage between largely recessive deleterious alleles, conditions which can lead to elevated heterozygosity via associative overdominance (AOD). Here we show that weakly selected QTLs linked to genomic regions exhibiting AOD can elevate VA above what is expected in the absence of unconditionally deleterious mutations. Selection on traits when VA is maintained by AOD, however, may expose recessive deleterious alleles as homozygotes, reducing fitness. Thus, while AOD may contribute to the maintenance of VA, variation maintained in this way may not be readily accessible by natural or artificial selection.
ER -