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Grueber CE, Farquharson KA, Wright BR, Wallis GP, Hogg CJ, Belov K. First evidence of deviation from Mendelian proportions in a conservation programme. Mol Ecol 2021; 30:3703-3715. [PMID: 34051005 DOI: 10.1111/mec.16004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Accepted: 05/05/2021] [Indexed: 11/29/2022]
Abstract
Classic Mendelian inheritance is the bedrock of population genetics and underpins pedigree-based management of animal populations. However, assumptions of Mendelian inheritance might not be upheld in conservation breeding programmes if early viability selection occurs, even when efforts are made to equalise genetic contributions of breeders. To test this possibility, we investigated deviations from Mendelian proportions in a captive metapopulation of the endangered Tasmanian devil. This marsupial population is ideal for addressing evolutionary questions in conservation due to its large size, range of enclosure types (varying in environmental conditions), good genomic resources (which aid interpretation), and the species' biology. Devil mothers give birth to more offspring than they can nurse in the pouch, providing the potential for intense viability selection amongst embryos. We used data from 140 known sire-dam-offspring triads to isolate within-family selection from population-level mechanisms (such as mate choice or inbreeding), and compared observed offspring genotypes at 123 targeted SNPs to neutral (i.e., Mendelian) expectations. We found lower offspring heterozygosity than expected, and subtle patterns that varied across a gradient of management intensity from zoo-like enclosures to semi-wild environments for some loci. Meiotic drive or maternal-foetal incompatibilities are consistent with our results, although we cannot statistically confirm these mechanisms. We found some evidence that maternal genotype affects annual litter size, suggesting that family-level patterns are driven by differential offspring mortality before birth or during early development. Our results show that deviations from Mendelian inheritance can occur in conservation programmes, despite best-practice management to prevent selection.
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Affiliation(s)
- Catherine E Grueber
- Faculty of Science, School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, Australia.,San Diego Zoo Global, San Diego, CA, USA
| | - Katherine A Farquharson
- Faculty of Science, School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, Australia
| | - Belinda R Wright
- Faculty of Science, School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, Australia
| | - Graham P Wallis
- Department of Zoology, University of Otago, Dunedin, New Zealand
| | - Carolyn J Hogg
- Faculty of Science, School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, Australia
| | - Katherine Belov
- Faculty of Science, School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, Australia
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Grueber CE, Peel E, Wright B, Hogg CJ, Belov K. A Tasmanian devil breeding program to support wild recovery. Reprod Fertil Dev 2020; 31:1296-1304. [PMID: 32172782 DOI: 10.1071/rd18152] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Accepted: 10/01/2018] [Indexed: 01/03/2023] Open
Abstract
Tasmanian devils are threatened in the wild by devil facial tumour disease: a transmissible cancer with a high fatality rate. In response, the Save the Tasmanian Devil Program (STDP) established an 'insurance population' to enable the preservation of genetic diversity and natural behaviours of devils. This breeding program includes a range of institutions and facilities, from zoo-based intensive enclosures to larger, more natural environments, and a strategic approach has been required to capture and maintain genetic diversity, natural behaviours and to ensure reproductive success. Laboratory-based research, particularly genetics, in tandem with adaptive management has helped the STDP reach its goals, and has directly contributed to the conservation of the species in the wild. Here we review this work and show that the Tasmanian devil breeding program is a powerful example of how genetic research can be used to understand and improve reproductive success in a threatened species.
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Affiliation(s)
- C E Grueber
- The University of Sydney, School of Life and Environmental Sciences, Faculty of Science, Sydney, NSW 2006, Australia
| | - E Peel
- The University of Sydney, School of Life and Environmental Sciences, Faculty of Science, Sydney, NSW 2006, Australia
| | - B Wright
- The University of Sydney, School of Life and Environmental Sciences, Faculty of Science, Sydney, NSW 2006, Australia
| | - C J Hogg
- The University of Sydney, School of Life and Environmental Sciences, Faculty of Science, Sydney, NSW 2006, Australia
| | - K Belov
- The University of Sydney, School of Life and Environmental Sciences, Faculty of Science, Sydney, NSW 2006, Australia
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Gooley RM, Hogg CJ, Fox S, Pemberton D, Belov K, Grueber CE. Inbreeding depression in one of the last DFTD-free wild populations of Tasmanian devils. PeerJ 2020; 8:e9220. [PMID: 32587794 PMCID: PMC7304431 DOI: 10.7717/peerj.9220] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 04/28/2020] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND Vulnerable species experiencing inbreeding depression are prone to localised extinctions because of their reduced fitness. For Tasmanian devils, the rapid spread of devil facial tumour disease (DFTD) has led to population declines and fragmentation across the species' range. Here we show that one of the few remaining DFTD-free populations of Tasmanian devils is experiencing inbreeding depression. Moreover, this population has experienced a significant reduction in reproductive success over recent years. METHODS We used 32 microsatellite loci to examine changes in genetic diversity and inbreeding in the wild population at Woolnorth, alongside field data on breeding success from females to test for inbreeding depression. RESULTS Wefound that maternal internal relatedness has a negative impact on litter sizes. The results of this study imply that this population may be entering an extinction vortex and that to protect the population genetic rescue should be considered. This study provides conservation managers with useful information for managing wild devils and provides support for the "Wild Devil Recovery Program", which is currently augmenting small, isolated populations.
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Affiliation(s)
- Rebecca M. Gooley
- School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales, Australia
| | - Carolyn J. Hogg
- School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales, Australia
| | - Samantha Fox
- Save the Tasmanian Devil Program, Hobart, Tasmania, Australia
- Toledo Zoo, Toledo, OH, United States of America
| | - David Pemberton
- Save the Tasmanian Devil Program, Hobart, Tasmania, Australia
| | - Katherine Belov
- School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales, Australia
| | - Catherine E. Grueber
- School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales, Australia
- San Diego Zoo Global, San Diego, CA, United States of America
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Flies AS, Flies EJ, Fox S, Gilbert A, Johnson SR, Liu GS, Lyons AB, Patchett AL, Pemberton D, Pye RJ. An oral bait vaccination approach for the Tasmanian devil facial tumor diseases. Expert Rev Vaccines 2020; 19:1-10. [PMID: 31971036 DOI: 10.1080/14760584.2020.1711058] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Introduction: The Tasmanian devil (Sarcophilus harrisii) is the largest extant carnivorous marsupial. Since 1996, its population has declined by 77% primarily due to a clonal transmissible tumor, known as devil facial tumor (DFT1) disease. In 2014, a second transmissible devil facial tumor (DFT2) was discovered. DFT1 and DFT2 are nearly 100% fatal.Areas covered: We review DFT control approaches and propose a rabies-style oral bait vaccine (OBV) platform for DFTs. This approach has an extensive safety record and was a primary tool in large-scale rabies virus elimination from wild carnivores across diverse landscapes. Like rabies virus, DFTs are transmitted by oral contact, so immunizing the oral cavity and stimulating resident memory cells could be advantageous. Additionally, exposing infected devils that already have tumors to OBVs could serve as an oncolytic virus immunotherapy. The primary challenges may be identifying appropriate DFT-specific antigens and optimization of field delivery methods.Expert opinion: DFT2 is currently found on a peninsula in southern Tasmania, so an OBV that could eliminate DFT2 should be the priority for this vaccine approach. Translation of an OBV approach to control DFTs will be challenging, but the approach is feasible for combatting ongoing and future disease threats.
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Affiliation(s)
- Andrew S Flies
- Menzies Institute for Medical Research, College of Health and Medicine, University of Tasmania, Hobart, Australia
| | - Emily J Flies
- School of Natural Sciences, College of Sciences and Engineering, University of Tasmania, Sandy Bay, Australia
| | - Samantha Fox
- Save the Tasmanian Devil Program, DPIPWE, Hobart, Australia.,Toledo Zoo, Toledo, OH, USA
| | - Amy Gilbert
- National Wildlife Research Center, USDA, APHIS, Wildlife Services, Fort Collins, CO, USA
| | - Shylo R Johnson
- National Wildlife Research Center, USDA, APHIS, Wildlife Services, Fort Collins, CO, USA
| | - Guei-Sheung Liu
- Menzies Institute for Medical Research, College of Health and Medicine, University of Tasmania, Hobart, Australia.,Ophthalmology, Department of Surgery, University of Melbourne, East Melbourne, Australia
| | - A Bruce Lyons
- School of Medicine, College of Health and Medicine, University of Tasmania, Hobart, Australia
| | - Amanda L Patchett
- Menzies Institute for Medical Research, College of Health and Medicine, University of Tasmania, Hobart, Australia
| | | | - Ruth J Pye
- Menzies Institute for Medical Research, College of Health and Medicine, University of Tasmania, Hobart, Australia
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Grueber CE, Fox S, McLennan EA, Gooley RM, Pemberton D, Hogg CJ, Belov K. Complex problems need detailed solutions: Harnessing multiple data types to inform genetic management in the wild. Evol Appl 2019; 12:280-291. [PMID: 30697339 PMCID: PMC6346650 DOI: 10.1111/eva.12715] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 08/15/2018] [Accepted: 09/04/2018] [Indexed: 12/18/2022] Open
Abstract
For bottlenecked populations of threatened species, supplementation often leads to improved population metrics (genetic rescue), provided that guidelines can be followed to avoid negative outcomes. In cases where no "ideal" source populations exist, or there are other complicating factors such as prevailing disease, the benefit of supplementation becomes uncertain. Bringing multiple data and analysis types together to plan genetic management activities can help. Here, we consider three populations of Tasmanian devil, Sarcophilus harrisii, as candidates for genetic rescue. Since 1996, devil populations have been severely impacted by devil facial tumour disease (DFTD), causing significant population decline and fragmentation. Like many threatened species, the key threatening process for devils cannot currently be fully mitigated, so species management requires a multifaceted approach. We examined diversity of 31 putatively neutral and 11 MHC-linked microsatellite loci of three remnant wild devil populations (one sampled at two time-points), alongside computational diversity projections, parameterized by field data from DFTD-present and DFTD-absent sites. Results showed that populations had low diversity, connectivity was poor, and diversity has likely decreased over the last decade. Stochastic simulations projected further diversity losses. For a given population size, the effects of DFTD on population demography (including earlier age at death and increased female productivity) did not impact diversity retention, which was largely driven by final population size. Population sizes ≥500 (depending on the number of founders) were necessary for maintaining diversity in otherwise unmanaged populations, even if DFTD is present. Models indicated that smaller populations could maintain diversity with ongoing immigration. Taken together, our results illustrate how multiple analysis types can be combined to address complex population genetic challenges.
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Affiliation(s)
- Catherine E. Grueber
- Faculty of Science, School of Life and Environmental SciencesThe University of SydneySydneyNew South WalesAustralia
- San Diego Zoo GlobalSan DiegoCalifornia
| | - Samantha Fox
- Save the Tasmanian Devil ProgramDPIPWEHobartTasmaniaAustralia
- Toledo ZooToledoOhio
| | - Elspeth A. McLennan
- Faculty of Science, School of Life and Environmental SciencesThe University of SydneySydneyNew South WalesAustralia
| | - Rebecca M. Gooley
- Faculty of Science, School of Life and Environmental SciencesThe University of SydneySydneyNew South WalesAustralia
| | - David Pemberton
- Save the Tasmanian Devil ProgramDPIPWEHobartTasmaniaAustralia
| | - Carolyn J. Hogg
- Faculty of Science, School of Life and Environmental SciencesThe University of SydneySydneyNew South WalesAustralia
- Zoo and Aquarium Association AustralasiaMosmanNew South WalesAustralia
| | - Katherine Belov
- Faculty of Science, School of Life and Environmental SciencesThe University of SydneySydneyNew South WalesAustralia
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