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Asynchronous male and female gonadal cycles and plasma steroid concentrations in a viviparous lizard, Niveoscincus ocellatus (Scincidae), from Tasmania

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Jones, SM and Wapstra, E and Swain, R (1997) Asynchronous male and female gonadal cycles and plasma steroid concentrations in a viviparous lizard, Niveoscincus ocellatus (Scincidae), from Tasmania. General and Comparative Endocrinology, 108 (2). pp. 271-281. ISSN 0016-6480

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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.

Item Type: Article
Journal or Publication Title: General and Comparative Endocrinology
Page Range: pp. 271-281
ISSN: 0016-6480
Identification Number - DOI: 10.1006/gcen.1997.6971
Additional Information: Definitive version is available online at http://www.sciencedirect.com/
Date Deposited: 15 Nov 2007 02:45
Last Modified: 18 Nov 2014 03:24
URI: http://eprints.utas.edu.au/id/eprint/2423
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