Thomas Nia Evelyn, Chadwick Elizabeth A, Bruford Michael W, Hailer Frank
Organisms and Environment, School of Biosciences and Water Research Institute Cardiff University Wales UK.
Cardiff University - Institute of Zoology Joint Laboratory for Biocomplexity Research (CIBR) Chinese Academy of Sciences Beijing China.
Evol Appl. 2025 Jan 17;18(1):e70067. doi: 10.1111/eva.70067. eCollection 2025 Jan.
Conservation efforts are leading to demographic growth and spatial expansion of some previously endangered species. However, past population bottlenecks or population size fluctuations can have lasting effects on effective population size ( ), even when census size ( ) appears large or recovered. The UK metapopulation of Eurasian otters () has a well-documented history of population recovery over recent decades, with indicators of presence (faeces and footprints) increasing in distribution and number over successive national surveys. To determine whether this increase in is reflected in increased , we analysed a large-scale microsatellite dataset (21 years: 1993-2014; 407 individuals) for signals of recent change using BOTTLENECK and LDNe, and evaluated potential biases associated with unaccounted spatial genetic structuring and inclusion of admixed genotypes. We obtained clear bottleneck signals in East England, and signals of recent population expansion in Wales and South West England in some analyses, consistent with national otter surveys and recent findings from whole-genome sequencing. Analyses that did not account for spatial genetic structuring yielded strong spurious signals of United Kingdom-wide population expansion, and estimates from these analyses were suppressed by a factor of 3-4. Inclusion of admixed individuals had weaker impacts on estimates, with overlapping 95% confidence intervals from different analyses. Notably, total summed across regions was small and well below the = 500 size deemed necessary for long-term population viability (sum of river basin district groups: 170.6, 95% C.I.: 102.1-348.3). Conclusions drawn from UK otter surveys, which had suggested a robust population close to panmixia, are therefore not supported by our genetic evidence. Our study highlights the value of including genetic monitoring of endangered or recovering species in monitoring plans, while also providing methodologically important information about estimation from real-world datasets.
保护工作正促使一些先前濒危物种的种群数量增长和空间扩张。然而，过去的种群瓶颈或种群数量波动可能会对有效种群大小（ ）产生持久影响，即使普查种群大小（ ）看起来很大或已恢复。英国欧亚水獭的集合种群在近几十年有记载的种群恢复历史，在连续的全国性调查中，出现迹象（粪便和足迹）的分布和数量都在增加。为了确定 的这种增加是否反映在 的增加上，我们分析了一个大规模微卫星数据集（21年：1993 - 2014年；407个个体），使用BOTTLENECK和LDNe来寻找近期 变化的信号，并评估与未考虑的空间遗传结构和混合基因型纳入相关的潜在偏差。我们在英格兰东部获得了明显的瓶颈信号，在一些分析中，威尔士和英格兰西南部有近期种群扩张的信号，这与全国水獭调查以及全基因组测序的近期发现一致。未考虑空间遗传结构的分析产生了全英种群扩张的强烈虚假信号，这些分析得出的 估计值被压低了三到四倍。纳入混合个体对 估计值的影响较弱，不同分析的95%置信区间有重叠。值得注意的是，各区域的总 很小，远低于长期种群生存能力所需的 = 500的大小（流域区组总和：170.6，95%置信区间：102.1 - 348.3）。因此，我们的遗传证据不支持英国水獭调查得出的结论，即认为种群强大且接近随机交配。我们的研究强调了在监测计划中纳入濒危或正在恢复物种的遗传监测的价值，同时也提供了关于从实际数据集估计 的重要方法学信息。
