Genetic variation in recombination rates and genetic shuffling in pigs, cattle and Atlantic salmon

• Main Author: Brekke, Cathrine
• Other Authors: Berg, Peer, Johnston, Susan E., Gjuvsland, Arne B., Knutsen, Tim Martin
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Norwegian University of Life Sciences, Ås 2022
• Subjects: Recombination; Linkage; genetic shuffling; Atlanterhavslaks; Atlantic salmon
• Online Access: https://hdl.handle.net/11250/3038527

Meiotic recombination ensures proper segregation of homologues chromosomes in meiosis while also breaking down linkage disequilibrium and creating novel haplotypes by shuffling alleles of genes located on the same chromosome. Understanding how rates and distribution of meiotic recombination vary between populations, sex and individuals is of particular interest in breeding as it can break up unfavorable linkage and produce genetic variance to exploit in selection. In this study we use dense SNP marker data on full-sib families from Norwegian Red cattle, an Atlantic salmon breeding population and five different pig breeding populations to investigate the genetic variation in individual measures of recombination within and between domestic species. All three species exhibit marked sex differences, but with different direction and magnitude. Genome-wide rates are higher in females in pigs and Atlantic salmon, but higher in males in cattle. Heritability of genome-wide rates of recombination was low but significant in both sexes in all three species (ranging from h2 = 0.04 in female cattle to 0.12 in male Atlantic salmon) which is comparable to estimates in other mammalian species. We detected five regions associated with variation in individual recombination rates in pig with candidate genes associated with meiosis, namely PRDM7, MEI1, RNF212, SYCP2 and MSH4. In cattle, three loci were significantly associated with the trait with four candidate genes that have all been associated with individual recombination rates previously: CEP55, NEK9, MLH3 and RNF212b. The sex specific patterns of recombination in pigs and Atlantic salmon lead to marked differences in the amount of intrachromosomal shuffling of alleles in maternal and paternal gametes, however it is not clear how this affects the overall genetic shuffling in a breeding population across generations. The genetic variation, and oligogenic architecture suggests a potential for genetic change in overall rates and distribution of recombination in these populations. ...