Wildlife Research Wildlife Research Society
Ecology, management and conservation in natural and modified habitats
RESEARCH ARTICLE

Inbreeding and testicular abnormalities in a bottlenecked population of koalas (Phascolarctos cinereus)

Romane Cristescu A H , Valma Cahill B , William B. Sherwin A , Kathrine Handasyde C , Kris Carlyon A , Desley Whisson D , Catherine A. Herbert A E , Britt Louise J. Carlsson F , Alan N. Wilton F G and Des W. Cooper A

A School of Biological, Earth and Environmental Sciences, University of New South Wales, NSW 2052, Australia.

B Creek Street, Oakey, Qld 4401, Australia.

C Department of Zoology, University of Melbourne, Vic. 3010, Australia.

D School of Life and Environmental Sciences, Deakin University, 221 Burwood Highway, Burwood, Vic. 3125, Australia.

E Faculty of Veterinary Science, University of Sydney, Sydney, NSW 2006, Australia.

F School of Biotechnology and Biomolecular Sciences, University of New South Wales, NSW 2052, Australia.

G Ramaciotti Centre for Gene Function Analysis, University of New South Wales, NSW 2052, Australia.

H Corresponding author. Email: romane@student.unsw.edu.au

Wildlife Research 36(4) 299-308 https://doi.org/10.1071/WR08010
Submitted: 23 January 2008  Accepted: 23 March 2009   Published: 1 June 2009

Abstract

Habitat destruction and fragmentation, interactions with introduced species or the relocation of animals to form new populations for conservation purposes may result in a multiplication of population bottlenecks. Examples are the translocations of koalas to French Island and its derivative Kangaroo Island population, with both populations established as insurance policies against koala extinction. In terms of population size, these conservation programs were success stories. However, the genetic story could be different. We conducted a genetic investigation of French and Kangaroo Island koalas by using 15 microsatellite markers, 11 of which are described here for the first time. The results confirm very low genetic diversity. French Island koalas have 3.8 alleles per locus and Kangaroo Island koalas 2.4. The present study found a 19% incidence of testicular abnormality in Kangaroo Island animals. Internal relatedness, an individual inbreeding coefficient, was not significantly different in koalas with testicular abnormalities from that in other males, suggesting the condition is not related to recent inbreeding. It could instead result from an unfortunate selection of founder individuals carrying alleles for testicular abnormalities, followed by a subsequent increase in these alleles’ frequencies through genetic drift and small population-related inefficiency of selection. Given the low diversity and possible high prevalence of deleterious alleles, the genetic viability of the population remains uncertain, despite its exponential growth so far. This stands as a warning to other introductions for conservation reasons.


Acknowledgements

This work was funded by ARC linkage grant (LPO560344). We thank the Department for Environment and Heritage (DEH), South Australia, for providing access to unpublished data from the Koala Management Program. We also thank the Rangers from French Island National Park (Parks Victoria) and the members of the Koala Management Program (DEH) for their support and assistance in the field and Bill Amos for providing the program to estimate IR. We also thank Andrea Taylor and three anonymous reviewers for their most helpful comments. All the work and particularly manipulations of koalas were approved by relevant ethic committees and accredited with relevant licences and permits. Authorisations were obtained under the Prevention of Cruelty to Animals Act 1985 (SA), Licence #46, dated 14 October 1997, the Macquarie University ACEC Permit #97041, the University of Melbourne Science Animal Experimentation Ethics Committee Project #03147, the Victorian Department of Sustainability & Environment Wildlife Research Permit #10003860, the Department for Environment and Heritage, South Australia, Wildlife Ethics Committee Approval #45/2005, Scientific Research Permit #E25038-2 and Licence #169.


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