Tracking Chromosomal Origins in the Northern Italy System of Metacentric Races of the House Mouse

The Western European house mouse is chromosomally diverse, with diploid karyotypes ranging from the standard 40 telocentric chromosomes down to 22 chromosomes. Karyotypes are modified through Robertsonian (Rb) fusion of 2 telocentrics into a single metacentric, occurring repeatedly with fixation, and whole-arm reciprocal translocations (WARTs) generating additional novel karyotypes. Over 100 metacentric populations (chromosomal races) have been identified, geographically clustered into “systems.” Chromosomal races within systems often hybridise, and new races may emerge through this hybridisation (“zonal raciation”). We wished to determine the degree to which chromosomal races in a system have evolved independently or share common ancestry. Recombination between chromosome s from hybridising chromosomal races can erase the signals associated with a particular metacentric of interest, making inferences challenging. However, reduced recombination near the centromeres of chromosomal race-specific metacentrics makes centromere-adjacent markers ideal for solving this probl em. For the Northern Italy System (NIS), we used microsatellite markers near the centromere to test previous hypotheses about evolutionary relationships of 5 chromosomal races. We chose markers from chromosomes 1, 3, 4, and 6, all of which comprise one arm of a metacentric in at least 2 of these NIS metacentric populations. We used estimates of FST and RST, as well as principal components analyses and ne...

Source: Cytogenetic and Genome Research - December 1, 2022 Category: Genetics & Stem Cells Source Type: research