Biogeographic barriers such as rivers have been shown to shape spatial patterns of biodiversity in the Amazon basin, yet relatively little is known about the distribution of genetic variation across continuous rainforest. Here, we characterize the genetic structure of the brilliant-thighed poison frog (Allobates femoralis) across an 880 km long transect along the Purus-Madeira interfluve south of the Amazon river, based on 64 individuals genotyped at 7 609 SNP loci. A population tree and clustering analyses revealed four distinct genetic groups, one of which was strongly divergent. These genetic groups were concomitant with femoral spot coloration differences, which was intermediate within a zone of admixture between two of the groups. The location of these genetic groups did not consistently correspond to current ecological transitions between major forest types. A multi-model approach to quantify the relative influence of isolation-by-distance (IBD) and isolation-by-environmental resistance (IBR) nevertheless revealed that, in addition to a strong signal of IBD, spatial genetic differentiation was explained by IBR primarily linked to dry season intensity (r 2 = 8.4%) and canopy cover (r 2 = 6.4%). We show significant phylogenetic divergence in the absence of obvious biogeographical barriers and that finer-scaled measures of genetic structure show patterns that are associated with environmental variables also known to predict the density of A. femoralis.

中文翻译：

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环境变异对分布于连续亚马逊雨林的毒蛙遗传结构的影响

河流等生物地理障碍已被证明可以塑造亚马逊流域生物多样性的空间格局，但对连续雨林中遗传变异的分布知之甚少。在这里，我们基于在 7 609 个 SNP 位点进行基因分型的 64 个个体，在亚马逊河以南的 Purus-Madeira 交汇处沿 880 公里长的横断面表征了亮大腿毒蛙（Allobates femoralis）的遗传结构。种群树和聚类分析揭示了四个不同的遗传组，其中一个非常不同。这些遗传组伴随着股骨斑点颜色差异，这是两个组之间的混合区域的中间区域。这些遗传群体的位置与当前主要森林类型之间的生态转变不一致。然而，一种量化距离隔离 (IBD) 和环境抗性隔离 (IBR) 相对影响的多模型方法表明，除了 IBD 的强信号外，空间遗传分化主要由 IBR 解释与旱季强度 (r 2 = 8.4%) 和树冠盖度 (r 2 = 6.4%) 相关。我们在没有明显的生物地理障碍的情况下显示出显着的系统发育差异，并且更精细的遗传结构测量显示与环境变量相关的模式，也已知可预测 A. femoralis 的密度。然而，一种量化距离隔离 (IBD) 和环境抗性隔离 (IBR) 相对影响的多模型方法表明，除了 IBD 的强信号外，空间遗传分化主要由 IBR 解释与旱季强度 (r 2 = 8.4%) 和树冠盖度 (r 2 = 6.4%) 相关。我们在没有明显的生物地理障碍的情况下显示出显着的系统发育差异，并且更精细的遗传结构测量显示与环境变量相关的模式，也已知可预测 A. femoralis 的密度。然而，一种量化距离隔离 (IBD) 和环境抗性隔离 (IBR) 相对影响的多模型方法表明，除了 IBD 的强信号外，空间遗传分化主要由 IBR 解释与旱季强度 (r 2 = 8.4%) 和树冠盖度 (r 2 = 6.4%) 相关。我们在没有明显的生物地理障碍的情况下显示出显着的系统发育差异，并且更精细的遗传结构测量显示与环境变量相关的模式，也已知可预测 A. femoralis 的密度。