title: Asynchronous male and female gonadal cycles and plasma steroid concentrations in a viviparous lizard, Niveoscincus ocellatus (Scincidae), from Tasmania.
abstract: The reproductive cycle in males of the skink, Niveoscincus ocellatus, is characterised by testicular development during summer, followed by mating in autumn. Plasma testosterone concentrations show a bimodal seasonal cycle, with the major peak (18.6 +/- 1.2 ng/ml) in late summer/autumn and a minor peak (7.4 +/- 1.0 ng/ml) at spring emergence. In contrast to the males, the females have a gonadal cycle in which mating is temporally dissociated from peak development of the gonads: ovulation occurs in spring and the young are born in summer. Fresh mating marks on females in spring indicate that at least part of the population mates for a second time after spring emergence. In females, plasma estradiol concentrations are significantly elevated (956 +/- 214 pg/ml) through vitellogenesis and are highest (1241 +/- 175 pg/ml) during the preovulatory phase. Plasma progesterone concentrations rise during gestation to 6.5 +/- 1.5 ng/ml, but fall in the final stage of gestation to 1.6 +/- 0.2 ng/ml. There is minimal atresia of vitellogenic follicles, suggesting that clutch size is determined when the follicles are recruited for vitellogenesis.
authors.affiliation: Department of Zoology, University of Tasmania, Hobart, TAS 7001, Australia.
authors.forename: S M
authors.initials: SM
authors.lastname: Jones
authors.forename: E
authors.initials: E
authors.lastname: Wapstra
authors.forename: R
authors.initials: R
authors.lastname: Swain
mesh_terms: D000818:Animals; D004958:Estradiol / Q000097:blood; D005260:Female; D006066:Gonads / Q000502:physiology*; D008116:Lizards / Q000502:physiology*; D008297:Male; D010060:Ovulation; D011374:Progesterone / Q000097:blood; D012098:Reproduction; D012621:Seasons; D013256:Steroids / Q000097:blood*; D013737:Testis / Q000502:physiology; D013739:Testosterone / Q000097:blood; D014818:Vitellogenesis
chemical_list: D013256:Steroids; D013739:Testosterone; D011374:Progesterone; D004958:Estradiol