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a Prince Henry's Institute of Medical Research, Clayton, Victoria 3168, Australia
b Department of Anatomy, Monash University, Clayton, Victoria 3168, Australia
c Conservation & Research Unit, Zoological Parks & Gardens Board, Parkville, Victoria 3052, Australia
ABSTRACT
Little is known about the reproductive biology of Australia's critically endangered northern hairy-nosed wombat (Lasiorhinus krefftii), largely due to its cryptic nature and the difficulty in accessing the small remaining population of about 70 animals. Using the noninvasive technique of fecal steroid analysis, we have examined the endocrinology of the more common yet closely related southern hairy-nosed wombat (Lasiorhinus latifrons). The aims of this study were to 1) develop and validate fecal androgen analysis in this species, 2) examine and compare seasonal differences in fecal and plasma androgens in male wombats, and 3) correlate seasonal differences in androgens with changes in male accessory glands (prostate and bulbourethral gland). Fecal androgens were extracted in ether; concentrated; separated by HPLC into testosterone (T), dihydrotestosterone (DHT), and 5
-androstane-3
,17ß-diol (Adiol) fractions; and quantitated by RIA. The concentrations of androgens in fecal pellets from 14 wild southern hairy-nosed wombats as determined by RIA varied over the range 6.625.0 ng/g dry weight for T, 4.024.2 ng/g dry weight for DHT, and 034.8 ng/g dry weight for Adiol. For each androgen, a highly significant linear correlation was observed between plasma and fecal concentrations. When individuals were grouped into either breeding season (pellets collected between AugustNovember) or nonbreeding season (collected between FebruaryApril), significant (P < 0.05) differences between seasons were observed for both plasma and fecal T, plasma DHT, and fecal Adiol. For all androgens, the mean fecal and plasma concentrations were higher during the breeding season than the nonbreeding season. A significant (P < 0.001) correlation was observed between fecal T and prostate weight, while DHT and Adiol correlations were nonsignificant. Significant correlations were observed, however, between all three fecal androgens and bulbourethral gland weight. These studies demonstrate that fecal T is a valid indicator of reproductive status in the male southern hairy-nosed wombat, with significant correlations observed between fecal T, plasma T, and prostate and bulbourethral gland weights. These findings have important implications for the study of the reproductive endocrinology of the critically endangered northern hairy-nosed wombat.
First decision: 20 January 1999.
1 The financial assistance of the Endangered Species Unit, Environment Australia, and the Queensland Department of Environment and Heritage is gratefully acknowledged.
2 Correspondence: Peter Temple-Smith, Director, Conservation and Research, Zoological Parks and Gardens Board, P.O. Box 74, Parkville, Victoria 3052, Australia. FAX: 61 3 9285 9346; ptsmith{at}zoo.org.au
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