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Evolutionary, molecular and comparative zoology
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RESEARCH ARTICLE
Contents Vol 57(2)

Age and seasonal changes in the semiochemicals of the sternal gland secretions of male koalas (Phascolarctos cinereus)

J. R. Tobey A C , T. R. Nute B and F. B. Bercovitch A
+ Author Affiliations
- Author Affiliations

A San Diego Zoo’s Institute for Conservation Research, 15600 San Pasqual Valley Road, Escondido, CA 92027, USA.

B Expert Chemical Analysis Inc., 10366 Roselle Street #C, San Diego, CA 92121, USA.

C Corresponding author. Email: jtobey@sandiegozoo.org

Australian Journal of Zoology 57(2) 111-118 https://doi.org/10.1071/ZO08090
Submitted: 2 December 2008  Accepted: 15 June 2009   Published: 21 July 2009

Abstract

Male koalas communicate with conspecifics using scent markings from their sternal scent gland. We examined age and seasonal changes in the profile of organic compounds produced by koala sternal glands. Scent exudates from 12 male koalas were collected over a one-year period and analysed by direct-injection gas chromatography–mass spectrometry (GC–MS) of the methanol extract. Carboxylic acids, aldehydes, ketones, and alcohols were found to dominate the scent mixture. Thirty-seven compounds were identified by comparison of their spectra with those in the Wiley 138K library. The identity, complexity and relative concentrations of these compounds were found to vary both seasonally and by age of the individuals, with the most odorous and complex mixtures occurring during the mating season. We suggest that seasonal and age differences in the complexity of the chemical composition of the koala scent gland exudate provides evidence that olfactory communication probably has important ramifications for male reproductive success in the wild.

Additional keywords: gas chromatography, mass spectrometry, olfactory communication.


Acknowledgments

We thank Carmi Penny for facilitating this research, as well as those individuals who helped with scent sample collection at the San Diego Zoo, especially Chris Hamlin-Andrus, Lenna Doyle, Jennifer Moll, Mel Cote and Amy Alfrey. A special thanks to The Menard Family Foundation for funding and to Corinne Pisacane for sharing her insights about chemical profiles. This study was approved by the Institutional Animal Care and Use Committee of the Zoological Society of San Diego (Proposal #165), and was conducted in compliance with all appropriate animal welfare rules and regulations.


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