Pedigree reconstruction using molecular data reveals an early warning sign of gene diversity loss in an island population of Tasmanian devils (Sarcophilus harrisii)
Tasmanian devils have experienced an 85% population decline since the emergence of an infectious cancer. In response, a captive insurance population was established in 2006 with a subpopulation later introduced onto Maria Island, Tasmania. We aimed to (1) examine the genetic parameters of the Maria Island population as a stand-alone site and within its broader metapopulation context, (2) assess the efficacy of assisted colonisations, and (3) inform future translocations. This study reconstructs the pedigree of 86 island-born devils using 31 polymorphic microsatellite loci. Combined molecular and pedigree analysis was used to monitor change in population genetic parameters in 4 years since colonisation. Molecular analysis alone revealed no significant change in genetic diversity, while DNA-reconstructed pedigree analysis revealed a statistically significant increase in inbreeding due to skewed founder representation. Pedigree modelling predicted that gene diversity would only be maintained above the threshold of 95% for a further 2 years, dropping to 77.1% after 40 years. Modelling alternative supplementation strategies revealed introducing eight new founders every 3 years will enable the population to retain 95% gene diversity until 2056, provided the translocated animals breed; to ensure this we recommend introducing ten new females every 3 years. We highlight the value of combining pedigree analyses with molecular data, from both a single-site and metapopulation viewpoint, for analysing changes in genetic parameters within populations of conservation concern. The importance of post-release genetic monitoring in an established population is emphasised, given how quickly inbreeding can accumulate and gene diversity be lost.
KeywordsGenetic monitoring Inbreeding Maria Island Metapopulation Translocation
We thank the Save the Tasmanian Devil Program, in particular Phil Wise and Drew Lee, for providing essential DNA samples and field observation data for the Maria Island devil population. Thank you to Drew Lee for providing a map of Maria Island used in Fig. 1. Thanks also to the studbook keeper (C. Srb) for her maintenance of the Tasmanian devil studbook and species management from the Zoo and Aquarium Association Australasia. We thank two anonymous reviewers for their comments that improved this manuscript.
Funding for this study was provided via an ARC Linkage grant to KB, CJH and CEG (LP140100508).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
All Tasmanian devils sampled as part of the monitoring for the Maria Island population were done so under permit and the standard operating procedure of the Tasmanian Department of Primary Industries, Population, Water and the Environment.
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