Context

Amazonian white-sand ecosystems (campinas) are open vegetation patches which form a natural island-like system in a matrix of tropical rainforest. Due to a clear distinction from the surrounding matrix, the spatial characteristics of campina patches may affect the genetic diversity and composition of their specialized organisms, such as the small and endemic passerine Elaenia ruficeps.

Objectives

To estimate the relative contribution of the current extension, configuration and geographical context of campina patches to the patterns of genetic diversity and population structure of E. ruficeps.

Methods

We sampled individuals of E. ruficeps from three landscapes in central Amazonia with contrasting campina spatial distribution, from landscapes with large and connected patches to landscapes with small and isolated patches. We estimated population structure, genetic diversity, and contemporary and historical migration within and among the three landscapes and used landscape metrics as predictor variables. Furthermore, we estimated genetic isolation by distance and resistance within landscapes.

Results

We identified three genetically distinct populations with asymmetrical gene flow among landscapes and a decreasing migration rate with distance. Within each landscape, we found low differentiation without genetic isolation by distance nor by resistance. In contrast, we found differentiation and spatial correlation between landscapes.

Conclusions

Together with previous studies, the population dynamics of E. ruficeps suggests that both regional context and landscape structure shape the connectivity among populations of campina specialist birds. Also, the spatial distribution of Amazonian landscapes, together with their associated biota, has changed in response to climatic changes in the Late Pleistocene.

中文翻译：

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亚马逊岛状生态系统的景观配置驱动了栖息地专家鸟类的种群结构和遗传多样性

上下文

亚马逊白沙生态系统 ( campinas ) 是开放的植被斑块，在热带雨林矩阵中形成一个天然的岛屿状系统。由于与周围基质的明显区别，坎皮纳斑块的空间特征可能会影响其特殊生物的遗传多样性和组成，例如小型和地方性的雀斑雀斑蝶。

目标

估计坎皮纳斑块的当前扩展、构造和地理背景对E. ruficeps遗传多样性模式和种群结构的相对贡献。

方法

我们从亚马逊中部的三个景观中采样了E. ruficeps个体，这些景观具有对比鲜明的坎皮纳空间分布，从具有大而相连斑块的景观到具有小而孤立斑块的景观。我们估计了三个景观内部和之间的人口结构、遗传多样性以及当代和历史迁移，并使用景观指标作为预测变量。此外，我们通过景观内的距离和阻力估计了遗传隔离。

结果

我们确定了三个基因不同的种群，它们在景观之间具有不对称的基因流动，并且迁移率随着距离的增加而降低。在每个景观中，我们发现在没有距离或抵抗力的遗传隔离的情况下，低分化。相比之下，我们发现景观之间的差异化和空间相关性。

结论

与先前的研究一起，E. ruficeps的种群动态表明区域环境和景观结构塑造了Campina专业鸟类种群之间的连通性。此外，亚马逊河流域景观的空间分布及其相关生物群已随着晚更新世的气候变化而变化。