title: About PAR: the distinct evolutionary dynamics of the pseudoautosomal region.
abstract: Sex chromosomes differ from other chromosomes in the striking divergence they often show in size, structure, and gene content. Not only do they possess genes controlling sex determination that are restricted to either the X or Y (or Z or W) chromosomes, but in many taxa they also include recombining regions. In these 'pseudoautosomal regions' (PARs), sequence homology is maintained by meiotic pairing and exchange in the heterogametic sex. PARs are unique genomic regions, exhibiting some features of autosomes, but they are also influenced by their partial sex linkage. Here we review the distribution and structure of PARs among animals and plants, the theoretical predictions concerning their evolutionary dynamics, the reasons for their persistence, and the diversity and content of genes that reside within them. It is now clear that the evolution of the PAR differs in important ways from that of genes in either the non-recombining regions of sex chromosomes or the autosomes.
authors.affiliation: Department of Zoology, 6270 University Boulevard, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
authors.forename: Sarah P
authors.initials: SP
authors.lastname: Otto
authors.forename: John R
authors.initials: JR
authors.lastname: Pannell
authors.forename: Catherine L
authors.initials: CL
authors.lastname: Peichel
authors.forename: Tia-Lynn
authors.initials: TL
authors.lastname: Ashman
authors.forename: Deborah
authors.initials: D
authors.lastname: Charlesworth
authors.forename: Adam K
authors.initials: AK
authors.lastname: Chippindale
authors.forename: Lynda F
authors.initials: LF
authors.lastname: Delph
authors.forename: Rafael F
authors.initials: RF
authors.lastname: Guerrero
authors.forename: Samuel V
authors.initials: SV
authors.lastname: Scarpino
authors.forename: Bryant F
authors.initials: BF
authors.lastname: McAllister
mesh_terms: D000465:Algorithms; D000818:Animals; D002874:Chromosome Mapping; D019143:Evolution, Molecular; D056426:Genetic Loci; D014644:Genetic Variation; D006801:Humans; D008957:Models, Genetic; D011995:Recombination, Genetic; D012727:Sex Characteristics; D012730:Sex Chromosomes / Q000235:genetics*