Testosterone and tusks: Maturation and seasonal reproductive patterns of live, free-ranging male dugongs (Dugong dugon) in a subtropical population

Burgess, Elizabeth A., Lanyon, Janet M. and Keeley, Tamara (2012) Testosterone and tusks: Maturation and seasonal reproductive patterns of live, free-ranging male dugongs (Dugong dugon) in a subtropical population. Reproduction, 143 5: 683-697.


Author Burgess, Elizabeth A.
Lanyon, Janet M.
Keeley, Tamara
Title Testosterone and tusks: Maturation and seasonal reproductive patterns of live, free-ranging male dugongs (Dugong dugon) in a subtropical population
Formatted title Testosterone and tusks: Maturation and seasonal reproductive patterns of live, free-ranging male dugongs (Dugong dugon) in a subtropical population
Journal name Reproduction   Check publisher's open access policy
ISSN 1470-1626
1741-7899
Publication date 2012-05
Sub-type Article (original research)
DOI 10.1530/REP-11-0434
Volume 143
Issue 5
Start page 683
End page 697
Total pages 15
Place of publication Bristol, United Kingdom
Publisher BioScientifica
Collection year 2013
Language eng
Formatted abstract Knowledge of male reproductive status and activity in free-ranging animals is vital to understanding reproductive patterns and population dynamics. Until now, almost all information regarding reproductive behavior of the dugong, a cryptic marine mammal, has relied on post-mortem examination. We examined the relationships between body length, tusk eruption (secondary sexual characteristic), seasonality, and group association on fecal testosterone metabolite concentrations in 322 free-ranging dugongs (159 males, 163 females) in subtropical Moreton Bay, Australia. Fecal testosterone concentrations demonstrated biologically meaningful differences in testicular activity between sexes and across reproductive/age classes, and were correlated with circulating concentrations in serum. Male dugongs have a pre-reproductive period that persists until a body length of 240 cm is achieved. Puberty apparently occurs between 240 and 260 cm body length when fecal testosterone levels increase fourfold (O500 ng/g) over juvenile levels, and is associated with tusk eruption. However, social maturity may be delayed until male dugongs are larger than 260 cm with well-developed tusks. In mature males, the lowest (!500 ng/g) fecal testosterone concentrations occur in the austral autumn months with maximal concentrations in September-October, coincident with the onset of a spring mating season. During spring, solitary mature males had fecal testosterone concentrations double those of mature males sampled within groups, potentially suggesting a mating strategy involving roving of reproductively active males. This study demonstrates that single-point physiological data from individuals across a population have value as indicators of reproductive processes. Our approach provides an efficacious non-lethal method for the census of reproductive status and seasonality in live male dugongs.
Keyword Male African elephants
Fecal testosterone
Loxodonta-Africana
Feeding season
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2013 Collection
School of Biological Sciences Publications
 
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