Mutation Load in Sunflower Inversions Is Negatively Correlated with Inversion Heterozygosity

作者：Kaichi Huang, Kate L. Ostevik, Cassandra Elphinstone, Marco Todesco, Natalia Bercovich, Gregory L. Owens, Loren H. Rieseberg · 发表于：Molecular Biology and Evolution · 年份：2022 · DOI：10.1093/molbev/msac101 · 被引用次数：51 · 研究领域：Chromosomal and Genetic Variations、RNA and protein synthesis mechanisms、Genetic diversity and population structure

Recombination is critical both for accelerating adaptation and purging deleterious mutations. Chromosomal inversions can act as recombination modifiers that suppress local recombination in heterozygotes and thus, under some conditions, are predicted to accumulate such mutations. In this study, we investigated patterns of recombination, transposable element abundance, and coding sequence evolution across the genomes of 1,445 individuals from three sunflower species, as well as within nine inversions segregating within species. We also analyzed the effects of inversion genotypes on 87 phenotypic traits to test for overdominance. We found significant negative correlations of long terminal repeat retrotransposon abundance and deleterious mutations with recombination rates across the genome in all three species. However, we failed to detect an increase in these features in the inversions, except for a modest increase in the proportion of stop codon mutations in several very large or rare inversions. Consistent with this finding, there was little evidence of overdominance of inversions in phenotypes that may relate to fitness. On the other hand, significantly greater load was observed for inversions in populations polymorphic for a given inversion compared to populations monomorphic for one of the arrangements, suggesting that the local state of inversion polymorphism affects deleterious load. These seemingly contradictory results can be explained by the low frequency of inversion ...