Chromosomal Inversions in Chromosome U of : A Story from Population Studies to Molecular Level.

is a Palearctic species that colonized the west coast of South and North America in the last quarter of the 20th century. This species stands out for its large chromosomal inversion polymorphism that affects its five long chromosomes. Studies of natural populations revealed that the inversion polymorphism has an adaptive character and while the arrangement U was classified as adapted to cold, other arrangements, such as U and U, were considered warm adapted. Characterization of the inversion breakpoints will allow a first approach to the genes included in the inversions and to find candidates to be affected by selection. In this work, we take advantage of the existence of a reference genomic sequence carrying the U arrangement to locate the breakpoints of the U and U inversions, mapping paired-end Illumina reads from two homokaryotypic strains to U and U, respectively. To date, most of the characterized inversion breakpoints in have been generated by non-homologous end-joining. In contrast, the U and U inversions seem to have originated by transposons, and, at the distal breakpoint of inversion U, we describe a new fold-back-like element characteristic of the suboscura species group that we have named .