Hohenlohe Paul A, McCallum Hamish I, Jones Menna E, Lawrance Matthew F, Hamede Rodrigo K, Storfer Andrew
Institute for Bioinformatics and Evolutionary Studies, Department of Biological Sciences, University of Idaho, Moscow, ID 83843, USA.
Environmental Futures Research Institute, Griffith University, Brisbane, QLD 4111, Australia.
Conserv Genet. 2019 Feb;20(1):81-87. doi: 10.1007/s10592-019-01157-5. Epub 2019 Feb 14.
Maintenance of adaptive genetic variation has long been a goal of management of natural populations, but only recently have genomic tools allowed identification of specific loci associated with fitness-related traits in species of conservation concern. This raises the possibility of managing for genetic variation directly relevant to specific threats, such as those due to climate change or emerging infectious disease. Tasmanian devils face the threat of a transmissible cancer, devil facial tumor disease (DFTD), that has decimated wild populations and led to intensive management efforts. Recent discoveries from genomic and modeling studies reveal how natural devil populations are responding to DFTD, and can inform management of both captive and wild devil populations. Notably, recent studies have documented genetic variation for disease-related traits and rapid evolution in response to DFTD, as well as potential mechanisms for disease resistance such as immune response and tumor regression in wild devils. Recent models predict dynamic persistence of devils with or without DFTD under a variety of modeling scenarios, although at much lower population densities than before DFTD emerged, contrary to previous predictions of extinction. As a result, current management that focuses on captive breeding and release for maintaining genome-wide genetic diversity or demographic supplementation of populations could have negative consequences. Translocations of captive devils into wild populations evolving with DFTD can cause outbreeding depression and/or increases in the force of infection and thereby the severity of the epidemic, and we argue that these risks outweigh any benefits of demographic supplementation in wild populations. We also argue that genetic variation at loci associated with DFTD should be monitored in both captive and wild populations, and that as our understanding of DFTD-related genetic variation improves, considering genetic management approaches to target this variation is warranted in developing conservation strategies for Tasmanian devils.
维持适应性遗传变异长期以来一直是自然种群管理的目标，但直到最近，基因组工具才使人们能够识别与受保护物种中与适应性相关性状相关的特定基因座。这增加了针对与特定威胁直接相关的遗传变异进行管理的可能性，比如那些由气候变化或新出现的传染病导致的威胁。袋獾面临着一种可传播癌症——袋獾面部肿瘤病（DFTD）的威胁，这种疾病已经使野生种群数量大幅减少，并促使人们进行密集管理。基因组和建模研究的最新发现揭示了袋獾自然种群对DFTD的反应方式，并可为圈养和野生袋獾种群的管理提供参考。值得注意的是，最近的研究记录了与疾病相关性状的遗传变异以及对DFTD的快速进化反应，还有野生袋獾的抗病潜在机制，如免疫反应和肿瘤消退。最近的模型预测了在各种建模情景下，有或没有DFTD时袋獾的动态持续性，尽管种群密度比DFTD出现之前要低得多，这与之前的灭绝预测相反。因此，目前侧重于圈养繁殖和放归以维持全基因组遗传多样性或对种群进行数量补充的管理可能会产生负面后果。将圈养袋獾转移到因DFTD而进化的野生种群中，可能会导致远交衰退和/或感染强度增加，从而使疫情更加严重，我们认为这些风险超过了对野生种群进行数量补充的任何好处。我们还认为，应该在圈养和野生种群中监测与DFTD相关基因座的遗传变异，并且随着我们对与DFTD相关遗传变异的理解不断加深，在制定袋獾保护策略时，考虑针对这种变异的遗传管理方法是有必要的。
