Kovach Ryan P, Muhlfeld Clint C, Wade Alisa A, Hand Brian K, Whited Diane C, DeHaan Patrick W, Al-Chokhachy Robert, Luikart Gordon
Northern Rocky Mountain Science Center, U.S. Geological Survey, West Glacier, MT, 59936, USA.
Flathead Biological Station, Fish and Wildlife Genomics Group, University of Montana, Polson, MT, 59860, USA.
Glob Chang Biol. 2015 Jul;21(7):2510-2524. doi: 10.1111/gcb.12850. Epub 2015 Feb 6.
Understanding how climatic variation influences ecological and evolutionary processes is crucial for informed conservation decision-making. Nevertheless, few studies have measured how climatic variation influences genetic diversity within populations or how genetic diversity is distributed across space relative to future climatic stress. Here, we tested whether patterns of genetic diversity (allelic richness) were related to climatic variation and habitat features in 130 bull trout (Salvelinus confluentus) populations from 24 watersheds (i.e., ~4-7th order river subbasins) across the Columbia River Basin, USA. We then determined whether bull trout genetic diversity was related to climate vulnerability at the watershed scale, which we quantified on the basis of exposure to future climatic conditions (projected scenarios for the 2040s) and existing habitat complexity. We found a strong gradient in genetic diversity in bull trout populations across the Columbia River Basin, where populations located in the most upstream headwater areas had the greatest genetic diversity. After accounting for spatial patterns with linear mixed models, allelic richness in bull trout populations was positively related to habitat patch size and complexity, and negatively related to maximum summer temperature and the frequency of winter flooding. These relationships strongly suggest that climatic variation influences evolutionary processes in this threatened species and that genetic diversity will likely decrease due to future climate change. Vulnerability at a watershed scale was negatively correlated with average genetic diversity (r = -0.77; P < 0.001); watersheds containing populations with lower average genetic diversity generally had the lowest habitat complexity, warmest stream temperatures, and greatest frequency of winter flooding. Together, these findings have important conservation implications for bull trout and other imperiled species. Genetic diversity is already depressed where climatic vulnerability is highest; it will likely erode further in the very places where diversity may be most needed for future persistence.
了解气候变化如何影响生态和进化过程对于做出明智的保护决策至关重要。然而，很少有研究测量气候变化如何影响种群内的遗传多样性，或者相对于未来气候压力，遗传多样性如何在空间上分布。在这里，我们测试了来自美国哥伦比亚河流域24个流域（即约4 - 7级河流子流域）的130个公牛鳟（Salvelinus confluentus）种群的遗传多样性模式（等位基因丰富度）是否与气候变化和栖息地特征相关。然后，我们确定公牛鳟的遗传多样性是否与流域尺度上的气候脆弱性相关，我们根据对未来气候条件（2040年代的预测情景）的暴露程度和现有的栖息地复杂性对其进行了量化。我们发现哥伦比亚河流域的公牛鳟种群遗传多样性存在强烈梯度，位于最上游源头地区的种群遗传多样性最高。在用线性混合模型考虑空间模式后，公牛鳟种群的等位基因丰富度与栖息地斑块大小和复杂性呈正相关，与夏季最高温度和冬季洪水频率呈负相关。这些关系强烈表明气候变化影响了这种濒危物种的进化过程，并且由于未来气候变化，遗传多样性可能会降低。流域尺度上的脆弱性与平均遗传多样性呈负相关（r = -0.77；P < 0.001）；包含平均遗传多样性较低种群的流域通常栖息地复杂性最低、溪流温度最高且冬季洪水频率最高。总之，这些发现对公牛鳟和其他濒危物种具有重要的保护意义。在气候脆弱性最高的地方，遗传多样性已经受到抑制；在未来物种存续可能最需要多样性的地方，它可能会进一步受到侵蚀。
