Nascent evolution of recombination rate differences as a consequence of chromosomal rearrangements

• Published in: PLoS genetics Vol. 19; no. 8; p. e1010717
• Main Authors: Näsvall, Karin, Boman, Jesper, Höök, Lars, Vila, Roger, Wiklund, Christer, Backström, Niclas
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 07.08.2023; Public Library of Science (PLoS)
• Subjects: Analysis; Biological diversity; Biology and life sciences; Butterflies; Chromosome rearrangements; Chromosomes; Comparative analysis; Ecology and Environmental Sciences; Estimates; Evolution; Gene mapping; Genetic aspects; Genetic diversity; Genetic polymorphisms; Genomes; Homologous recombination; Identification and classification; Karyotypes; Mutation; Natural selection; Organisms; People and places; Population genetics; Research and Analysis Methods; Segregation; Yeast; Sweden; Spain
• ISSN: 1553-7404; 1553-7390; 1553-7404
• DOI: 10.1371/journal.pgen.1010717

Reshuffling of genetic variation occurs both by independent assortment of chromosomes and by homologous recombination. Such reshuffling can generate novel allele combinations and break linkage between advantageous and deleterious variants which increases both the potential and the efficacy of natural selection. Here we used high-density linkage maps to characterize global and regional recombination rate variation in two populations of the wood white butterfly (Leptidea sinapis) that differ considerably in their karyotype as a consequence of at least 27 chromosome fissions and fusions. The recombination data were compared to estimates of genetic diversity and measures of selection to assess the relationship between chromosomal rearrangements, crossing over, maintenance of genetic diversity and adaptation. Our data show that the recombination rate is influenced by both chromosome size and number, but that the difference in the number of crossovers between karyotypes is reduced as a consequence of a higher frequency of double crossovers in larger chromosomes. As expected from effects of selection on linked sites, we observed an overall positive association between recombination rate and genetic diversity in both populations. Our results also revealed a significant effect of chromosomal rearrangements on the rate of intergenic diversity change between populations, but limited effects on polymorphisms in coding sequence. We conclude that chromosomal rearrangements can have considerable effects on the recombination landscape and consequently influence both maintenance of genetic diversity and efficiency of selection in natural populations.