title: Simultaneous Mendelian and clonal genome transmission in a sexually reproducing, all-triploid vertebrate.
abstract: Meiosis in triploids faces the seemingly insuperable difficulty of dividing an odd number of chromosome sets by two. Triploid vertebrates usually circumvent this problem through either asexuality or some forms of hybridogenesis, including meiotic hybridogenesis that involve a reproductive community of different ploidy levels and genome composition. Batura toads (Bufo baturae; 3n = 33 chromosomes), however, present an all-triploid sexual reproduction. This hybrid species has two genome copies carrying a nucleolus-organizing region (NOR+) on chromosome 6, and a third copy without it (NOR-). Males only produce haploid NOR+ sperm, while ova are diploid, containing one NOR+ and one NOR- set. Here, we conduct sibship analyses with co-dominant microsatellite markers so as (i) to confirm the purely clonal and maternal transmission of the NOR- set, and (ii) to demonstrate Mendelian segregation and recombination of the NOR+ sets in both sexes. This new reproductive mode in vertebrates ('pre-equalizing hybrid meiosis') offers an ideal opportunity to study the evolution of non-recombining genomes. Elucidating the mechanisms that allow simultaneous transmission of two genomes, one of Mendelian, the other of clonal inheritance, might shed light on the general processes that regulate meiosis in vertebrates.
authors: Department of Ecology and Evolution, University of Lausanne, Biophore, 1015 Lausanne, Switzerland.
authors: Matthias
authors: M
authors: Stöck
authors: Jana
authors: J
authors: Ustinova
authors: Caroline
authors: C
authors: Betto-Colliard
authors: Manfred
authors: M
authors: Schartl
authors: Craig
authors: C
authors: Moritz
authors: Nicolas
authors: N
authors: Perrin
mesh_terms: D000818:Animals; D002025:Bufonidae / Q000235:genetics* / Q000502:physiology; D003433:Crosses, Genetic; D004171:Diploidy; D019143:Evolution, Molecular; D005260:Female; D006238:Haploidy; D008297:Male; D008540:Meiosis / Q000235:genetics; D018895:Microsatellite Repeats; D008957:Models, Genetic; D009697:Nucleolus Organizer Region / Q000235:genetics; D010063:Ovum / Q000502:physiology; D011995:Recombination, Genetic; D012098:Reproduction / Q000235:genetics / Q000502:physiology; D013094:Spermatozoa / Q000502:physiology; D057885:Triploidy