Epistatic selection on a selfish Segregation Distorter supergene – drive, recombination, and genetic load
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eLife
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2022-04-29Referencia bibliográfica
Beatriz Navarro-Dominguez... [et al.] (2022) Epistatic selection on a selfish Segregation Distorter supergene – drive, recombination, and genetic load eLife 11:e78981 [https://doi.org/10.7554/eLife.78981]
Patrocinador
United States Department of Health & Human Services National Institutes of Health (NIH) - USA NIH National Institute of General Medical Sciences (NIGMS) R35 GM119515 F32GM105317Resumen
Meiotic drive supergenes are complexes of alleles at linked loci that together subvert
Mendelian segregation resulting in preferential transmission. In males, the most common mechanism
of drive involves the disruption of sperm bearing one of a pair of alternative alleles. While at
least two loci are important for male drive—the driver and the target—linked modifiers can enhance
drive, creating selection pressure to suppress recombination. In this work, we investigate the evolution
and genomic consequences of an autosomal, multilocus, male meiotic drive system, Segregation
Distorter (SD) in the fruit fly, Drosophila melanogaster. In African populations, the predominant
SD chromosome variant, SD-Mal,
is characterized by two overlapping, paracentric inversions on
chromosome arm 2R and nearly perfect (~100%) transmission. We study the SD-Mal
system in detail,
exploring its components, chromosomal structure, and evolutionary history. Our findings reveal a
recent chromosome-scale
selective sweep mediated by strong epistatic selection for haplotypes
carrying Sd, the main driving allele, and one or more factors within the double inversion. While
most SD-Mal
chromosomes are homozygous lethal, SD-Mal
haplotypes can recombine with other,
complementing haplotypes via crossing over, and with wildtype chromosomes via gene conversion.
SD-Mal
chromosomes have nevertheless accumulated lethal mutations, excess non-synonymous
mutations, and excess transposable element insertions. Therefore, SD-Mal
haplotypes evolve as a
small, semi-isolated
subpopulation with a history of strong selection. These results may explain the
evolutionary turnover of SD haplotypes in different populations around the world and have implications
for supergene evolution broadly.