Grueber Catherine E, Fox Samantha, McLennan Elspeth A, Gooley Rebecca M, Pemberton David, Hogg Carolyn J, Belov Katherine
Faculty of Science, School of Life and Environmental Sciences The University of Sydney Sydney New South Wales Australia.
San Diego Zoo Global San Diego California.
Evol Appl. 2018 Dec 26;12(2):280-291. doi: 10.1111/eva.12715. eCollection 2019 Feb.
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, , 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.
对于濒危物种的瓶颈种群而言,倘若能够遵循相关准则以避免负面结果,补充种群通常会带来种群指标的改善(基因拯救)。在不存在“理想”源种群的情况下,或者存在诸如流行疾病等其他复杂因素时,补充种群的益处就变得不确定了。整合多种数据和分析类型来规划基因管理活动会有所帮助。在此,我们将袋獾的三个种群视为基因拯救的候选对象。自1996年以来,袋獾种群受到袋獾面部肿瘤病(DFTD)的严重影响,导致种群数量显著下降和碎片化。与许多濒危物种一样,目前袋獾面临的关键威胁过程无法得到完全缓解,因此物种管理需要采取多方面的方法。我们研究了三个残余野生袋獾种群(其中一个在两个时间点进行了采样)的31个假定中性微卫星位点和11个与主要组织相容性复合体(MHC)相关的微卫星位点的多样性,同时结合了通过DFTD存在和不存在地点的实地数据进行参数化的计算多样性预测。结果表明,这些种群多样性较低,连通性较差,并且在过去十年中多样性可能有所下降。随机模拟预测多样性会进一步丧失。对于给定的种群规模,DFTD对种群人口统计学的影响(包括死亡年龄提前和雌性繁殖力增加)并未影响多样性的保留,多样性在很大程度上由最终种群规模驱动。即使存在DFTD,种群规模≥500(取决于奠基者数量)对于在其他未管理的种群中维持多样性也是必要的。模型表明,较小的种群可以通过持续的移民来维持多样性。综合来看,我们的结果说明了如何结合多种分析类型来应对复杂的种群遗传挑战。