Abstract
Captive breeding for conservation is widely used to prevent extinction, however these programs face many challenges due to small population size, founder effects, lack of migration and potential adaptation to captivity. Together these influence how selection, genetic drift and gene flow shape the genetic makeup of small populations, so examining these in a captive setting is valuable for appropriate biodiversity management. We have quantified the effects of selection, drift and gene flow in 503 individuals across five generations from the Tasmanian devil insurance population. To determine whether different processes were acting in different settings, we separately analysed animals housed under individual-based management, versus those that were released to an island site. We found that a greater proportion of alleles were lost over time in the smaller island population than in captivity and propose that genetic drift is the most likely process influencing this result. We found that the captive population became more heterozygous over time, while the island population stayed constant. Our molecular measure of inbreeding found a decrease over generations in captivity that is not captured by pedigree-based analysis. As management of breeding interactions only takes place in the captive population, our results are consistent with gene flow through managed breeding in captivity minimising inbreeding over time. Gene flow was also evident through changes to population structure in the captive population. Our findings serve as an example of how conservation managers can assess the impact of evolutionary processes on managed populations and adapt management practices if required.
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Acknowledgements
We thank the staff and management of the Save the Tasmanian Devil Program, the Zoo and Aquarium Association Australasia and all their member zoos who participate in the devil program. Thanks also to the past and present students and post-docs of the Australasian Wildlife Genomics Group at the University of Sydney. This work was funded by the Australian Research Council LP140100508 and DP170101253.
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This work was funded by the Australian Research Council LP140100508 and DP170101253.
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BW undertook statistical analyses, and prepared the first draft; CJH contributed to study design and project coordination, coordinated sample acquisition, and contributed to writing the manuscript; EAM undertook analysis of RRS data and contributed to writing the manuscript; KB contributed to study design and project coordination, and critically revised the manuscript; CEG contributed to study design and project coordination, oversaw statistical analyses, and contributed to writing the manuscript.
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Wright, B.R., Hogg, C.J., McLennan, E.A. et al. Assessing evolutionary processes over time in a conservation breeding program: a combined approach using molecular data, simulations and pedigree analysis. Biodivers Conserv 30, 1011–1029 (2021). https://doi.org/10.1007/s10531-021-02128-4
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DOI: https://doi.org/10.1007/s10531-021-02128-4