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Annual cycles of urinary reproductive steroid concentrations in wild and captive endangered Fijian ground frogs (Platymantis vitiana)

Narayan, Edward J. and Molinia, F.C. and Christi, Ketan S. and Morley, Craig and Cockrem, J.F. (2010) Annual cycles of urinary reproductive steroid concentrations in wild and captive endangered Fijian ground frogs (Platymantis vitiana). General and Comparative Endocrinology, 166 (1). pp. 172-179. ISSN 0016-6480

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Annual cycles of reproductive steroid metabolites were measured in urine collected from free-living and captive tropical endangered Fijian ground frogs (Platymantis vitiana) a terrestrial breeding. Free-living frogs were sampled on Viwa Island, Fiji and captive frogs were maintained in an outdoor enclosure in Suva, Fiji. Urinary estrone, progesterone and testosterone metabolite concentrations increased in male and female frogs after HCG challenges, with clear peaks in steroid concentrations 2 or 3 days after the challenges. There were annual cycles of testosterone metabolites in wild and captive males, and of estrone and progesterone metabolites in wild and captive females. Peaks of steroid concentrations in the wet season corresponded with periods of mating and egg laying in females in December and January. Steroid concentrations declined in January and February when maximum egg sizes in females were also declining. Body weights of wild male and vitellogenic female frogs showed annual cycles. Body weights of non-vitellogenic female frogs varied significantly between months, although there was no clear pattern of annual changes. Body weights of the 3 captive male frogs and 4 captive female frogs were similar to those of the wild frogs. Estrone metabolites were 80% successful in identifying non-vitellogenic females from males. The results suggest that the Fijian ground frog is a seasonal breeder with an annual gonadal cycle, and this species is likely to be photoperiodic. Urinary steroid measurements can provide useful information on reproductive cycles in endangered amphibians.

Item Type: Journal Article
Subjects: Q Science > QH Natural history > QH301 Biology
Divisions: Faculty of Science, Technology and Environment (FSTE) > School of Biological and Chemical Sciences
Depositing User: Ms Mereoni Camailakeba
Date Deposited: 24 May 2010 02:05
Last Modified: 16 Jul 2012 04:04

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