?s Apodemus peninsulae B chromosome B chromosomes B morphotypes DNA composition DNA copy number variation Drosophila FISH (fluorescence in situ hybridisation) GISH (genomic in situ hybridisation) Orthoptera Prospero autumnale complex RNA-Seq RepeatExplorer additional chromosomes centromere chromosome evolution chromosome polymorphism controlling element coverage ratio analysis cytogenetics de novo centromere formation dot-like (micro) Bs drive epigenetics euchromatin degradation evolution extra chromosomes fluorescent in situ hybridization genes