title: Sex chromosome evolution in moths and butterflies.
abstract: Lepidoptera, i.e. moths and butterflies, have a female heterogametic sex chromosome system, with most females having a WZ constitution while males are ZZ. Besides this predominant WZ/ZZ system, Z/ZZ, WZ(1)Z(2)/Z(1)Z(1)Z(2)Z(2) and W(1)W(2)Z/ZZ systems also occur. Sex is determined by an unknown W-linked gene or genes in Bombyx mori, but by dosage-dependent and equally unknown Z-linked genes in all Z/ZZ species. The female heterogametic sex chromosome system has been conserved for at least 180 MY in the phylogenetic branch that combines Lepidoptera and Trichoptera. The W chromosome, which is present in most lepidopteran species, was incorporated in the sex chromosome system much later, about 90-100 MY ago. The Z chromosomes are highly conserved among Lepidoptera, much like the Z in birds or the X in mammals. The W, on the other hand, is evolving rapidly. It is crammed with repetitive elements which appear to have a high turnover rate but poor in or even devoid of protein-coding genes. It has frequently undergone fusion with autosomes or sporadically lost altogether.
authors.affiliation: Laboratory of Applied Molecular Entomology, Research Faculty of Agriculture, Hokkaido University, Kita-ku, Sapporo, Japan. sahara@abs.agr.hokudai.ac.jp
authors.forename: Ken
authors.initials: K
authors.lastname: Sahara
authors.forename: Atsuo
authors.initials: A
authors.lastname: Yoshido
authors.forename: Walther
authors.initials: W
authors.lastname: Traut
mesh_terms: D000818:Animals; D002080:Butterflies / Q000145:classification / Q000235:genetics*; D022004:Chromosome Structures / Q000235:genetics; D059006:Chromosomes, Insect / Q000235:genetics* / Q000502:physiology; D055028:Comparative Genomic Hybridization; D004303:Dosage Compensation, Genetic; D019143:Evolution, Molecular; D005260:Female; D017344:Genes, Insect; D008297:Male; D009036:Moths / Q000145:classification / Q000235:genetics*; D012730:Sex Chromosomes / Q000145:classification / Q000235:genetics*; D019849:Sex Determination Processes; D026801:Synteny; D014178:Translocation, Genetic