Do divergent mitochondrial backgrounds alter the fate of nuclear alleles during hybridization and admixture?
- 1Brown University
Abstract
Hybridization brings together genetic variation from different populations or species into admixed genomes. As selection sorts this variation, the fate of each allele is determined by its fitness effect in the new hybrid genomic background. Because mitochondrial genes coevolve with the nuclear genome, they may be especially sensitive to foreign nuclear backgrounds, making them potential "hot-spots" for hybrid incompatibilities. Here, we test whether selection against mitonuclear incompatibilities drives repeatable hybridization outcomes. Specifically, we experimentally evolved three sets of five populations of hybrid Drosophila melanogaster, each carrying the same nuclear chromosomes but paired with one of three increasingly divergent mitochondrial DNA backgrounds. We hypothesized that accumulated incompatibilities would result in different patterns of nuclear admixture among mitochondrial backgrounds. To test this, we tracked nuclear allele frequencies in all 15 populations by whole-genome sequencing at intermediate time points. After 25 generations, we observed that rapid genomic evolution produced a strikingly parallel mosaic of both nuclear ancestries, independent of mitochondrial background. Contrary to our hypothesis, we found no evidence that mitochondrial background1 shaped nuclear admixture, even for interspecific combinations. These results suggest that in species with large effective population sizes, efficient purifying selection limits the accumulation of mitonuclear incompatibilities, allowing selection on nuclear alleles to promote repeatable ancestry sorting immediately following hybridization.
Related
- Sperm subpopulations differing in mitochondrial abundance show divergent nuclear allele frequencies
- Long‐term surveillance reveals hybridization by nuclear reassortment and intercontinental spread as major evolutionary drivers in wheat yellow rust
- Divergent mega-NUMT mimicking entirely functional complete mitochondrial genome
- A Cost-Effective, Kit-Free Method for Extracting Nuclear and Mitochondrial DNA From Low-Abundance Cells in Urine Samples.
- Chromosome-scale nuclear and mitochondrial genome assemblies reveal extreme genome compartmentalization in the hazelnut pathogen Anisogramma anomala
BibTeX
@misc{darwin2026divergent,
title = {{Do divergent mitochondrial backgrounds alter the fate of nuclear alleles during hybridization and admixture?}},
author = {L. J. Darwin and R. Z. Bachtel and F. A. Lemieux and Y. Raynes and D. M. Rand},
howpublished = {bioRxiv},
year = {2026},
month = nov,
doi = {10.64898/2026.11.04.764285},
url = {https://www.biorxiv.org/content/10.64898/2026.11.04.764285v1},
note = {CC BY-NC},
}
RIS
TY - UNPB
TI - Do divergent mitochondrial backgrounds alter the fate of nuclear alleles during hybridization and admixture?
AU - L. J. Darwin
AU - R. Z. Bachtel
AU - F. A. Lemieux
AU - Y. Raynes
AU - D. M. Rand
PY - 2026
DA - 2026/11/04
PB - bioRxiv
DO - 10.64898/2026.11.04.764285
UR - https://www.biorxiv.org/content/10.64898/2026.11.04.764285v1
AB - Hybridization brings together genetic variation from different populations or species into admixed genomes. As selection sorts this variation, the fate of each allele is determined by its fitness effect in the new hybrid genomic background. Because mitochondrial genes coevolve with the nuclear genome, they may be especially sensitive to foreign nuclear backgrounds, making them potential "hot-spots" for hybrid incompatibilities. Here, we test whether selection against mitonuclear incompatibilities drives repeatable hybridization outcomes. Specifically, we experimentally evolved three sets of five populations of hybrid Drosophila melanogaster, each carrying the same nuclear chromosomes but paired with one of three increasingly divergent mitochondrial DNA backgrounds. We hypothesized that accumulated incompatibilities would result in different patterns of nuclear admixture among mitochondrial backgrounds. To test this, we tracked nuclear allele frequencies in all 15 populations by whole-genome sequencing at intermediate time points. After 25 generations, we observed that rapid genomic evolution produced a strikingly parallel mosaic of both nuclear ancestries, independent of mitochondrial background. Contrary to our hypothesis, we found no evidence that mitochondrial background1 shaped nuclear admixture, even for interspecific combinations. These results suggest that in species with large effective population sizes, efficient purifying selection limits the accumulation of mitonuclear incompatibilities, allowing selection on nuclear alleles to promote repeatable ancestry sorting immediately following hybridization.
ER -