The genetic mating system, male reproductive success and lack of selection on male traits in the greater bilby
Emily J. Miller A B E , Mark D. B. Eldridge C , Neil Thomas D , Nicola Marlow D and Catherine A. Herbert A BA School of Biological, Earth and Environmental Sciences, University of New South Wales, Kensington, NSW 2052, Australia.
B Current address: Faculty of Veterinary Science, University of Sydney, Camperdown, NSW 2006, Australia.
C Molecular Biology, Australian Museum, 6 College Street, Sydney, NSW 2010, Australia.
D Department of Environment and Conservation, PO Box 51, Wanneroo, WA 6946, Australia.
E Corresponding author. Email: emily.miller@sydney.edu.au
Australian Journal of Zoology 58(2) 113-120 https://doi.org/10.1071/ZO09092
Submitted: 7 September 2009 Accepted: 14 May 2010 Published: 28 June 2010
Abstract
The greater bilby (Macrotis lagotis) is the sole remaining species of desert bandicoot on the Australian mainland. The mating system of this species remains poorly understood, due to the bilby’s cryptic nature. We investigated the genetic mating system of the greater bilby in a five-year study of a semi-free-ranging captive population that simulated their wild environment. Morphological traits were examined to determine whether these influenced patterns of male reproductive success and whether selection was acting on them. In any given year more than half the males (59.2 ± 9.3%) failed to sire any offspring. Approximately 70% of sires fathered one offspring, and 30% two or three offspring. Since paternity was not dominated by few males, and given the species’ solitary nature, lack of territoriality and large home ranges, it is likely that males adopt a roving strategy to find receptive females. These results are consistent with an overlap promiscuous mating system. Sires and non-sires could not be distinguished by their morphological traits, and there was no evidence for strong linear or non-linear selection on male traits. These data increase our understanding of bandicoot life-history traits and will assist conservation and management efforts.
Additional keywords: captive breeding, conservation, Macrotis lagotis, male morphology, selection analysis.
Acknowledgements
We thank Brian MacMahon, Martin Clarke and Howard Robinson (DEC, WA); State Trustees M. A. Ingram Trust; Molecular Ecology and Evolution Laboratory (UNSW); Jennifer Sinclair, Russell Bonduriansky, Rob Brooks, Clare Holleley; and Susi Zajitschek and Angela Moles for comments that greatly improved this manuscript. We also thank Angela Higgins (Ramaciotti Centre, UNSW). All experimental work carried out was approved by the Department of Environment and Conservation, Western Australia, under the approval numbers 2003/36, 2006/24 and 2009/46.
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