title: Genetics of sex determination in tilapiine species.
abstract: We identified DNA markers linked to sex determining genes in six closely related species of tilapiine fishes. The mode of sex determination differed among species. In Oreochromis karongae and Tilapia mariae the sex-determining locus is on linkage group (LG) 3 and the female is heterogametic (WZ-ZZ system). In O. niloticus and T. zillii the sex-determining locus is on LG1 and the male is heterogametic (XX-XY system). A more complex pattern was observed in O. aureus and O. mossambicus, in which markers on both LG1 and LG3 were associated with sex. We found evidence for sex-linked lethal effects on LG1, as well as interactions between loci in the two linkage groups. Comparison of genetic and physical maps demonstrated a broad region of recombination suppression harboring the sex-determining locus on LG3. Sex-specific recombination suppression was found in the female heterogametic sex. Sequence analysis showed the accumulation of repetitive elements in this region. Phylogenetic analysis suggests that at least two transitions in the mode of sex determination have occurred in this clade. This variation in sex determination mechanisms among closely related species makes tilapias an excellent model system for studying the evolution of sex chromosomes in vertebrates.
authors.affiliation: Department of Fisheries and Wildlife Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Va., USA.
authors.forename: A
authors.initials: A
authors.lastname: Cnaani
authors.forename: B-Y
authors.initials: BY
authors.lastname: Lee
authors.forename: N
authors.initials: N
authors.lastname: Zilberman
authors.forename: C
authors.initials: C
authors.lastname: Ozouf-Costaz
authors.forename: G
authors.initials: G
authors.lastname: Hulata
authors.forename: M
authors.initials: M
authors.lastname: Ron
authors.forename: A
authors.initials: A
authors.lastname: D'Hont
authors.forename: J-F
authors.initials: JF
authors.lastname: Baroiller
authors.forename: H
authors.initials: H
authors.lastname: D'Cotta
authors.forename: D J
authors.initials: DJ
authors.lastname: Penman
authors.forename: E
authors.initials: E
authors.lastname: Tomasino
authors.forename: J-P
authors.initials: JP
authors.lastname: Coutanceau
authors.forename: E
authors.initials: E
authors.lastname: Pepey
authors.forename: A
authors.initials: A
authors.lastname: Shirak
authors.forename: T D
authors.initials: TD
authors.lastname: Kocher
mesh_terms: D000818:Animals; D017756:Aquaculture; D005075:Biological Evolution; D001947:Breeding; D005260:Female; D005819:Genetic Markers; D005838:Genotype; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D010641:Phenotype; D010802:Phylogeny; D011995:Recombination, Genetic; D012730:Sex Chromosomes; D019849:Sex Determination Processes; D013045:Species Specificity; D017210:Tilapia / Q000235:genetics*
chemical_list: D005819:Genetic Markers