Spatial soft sweeps: Patterns of adaptation in populations with long-range dispersal
Spatial soft sweeps: Patterns of adaptation in populations with long-range dispersal
复制标题
空间软扫描：远距离扩散种群的适应模式
DOI：
10.1371/journal.pgen.1007936
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发表时间：
2018
期刊：
影响因子：
4.5
通讯作者：
O. Hallatschek
中科院分区：
文献类型：
--
作者：
J. Paulose;J. Hermisson;O. Hallatschek
扩展种群的适应通常是通过多个独立的突变来同时应对共同的选择压力。当突变同时在人群中传播时，它们在选定的基因座附近留下了多态性的特征模式，即所谓的软扫描，在适应完成后仍然可见。这些模式在有益突变的传播动力学的两个限制中得到了很好的理解：完全没有空间结构的泛繁殖情况，以及通过短程或扩散扩散事件传播，该事件将空间镶嵌成不同的紧凑区域，每个区域都来自一个独特的突变。然而，在大多数自然种群的传播行为并不完全是panmictic或扩散，但包括短距离和长距离的传播事件。在这里，我们的特点的空间模式的软扫描驱动的扩散事件，其跳跃距离广泛分布，使用基于格子的模拟和缩放参数。我们发现，突变体克隆采取了独特的结构，包括紧凑的核心周围的碎片“晕”混合从其他克隆的晕。作为远程分散变得更加突出，从扩散到panmictic行为的进展是由两个过渡分离制度与不同的相对大小的晕核心。我们分析的核心晕结构的影响，从人口的小基因组样本的软扫描检测的统计数据，并发现相反的影响，长程扩散的预期多样性在全球样本相比，从地理分区的范围内的本地样本。我们还讨论了软扫描对未来的适应和混合引起的常设遗传变异的后果。
Adaptation in extended populations often occurs through multiple independent mutations responding in parallel to a common selection pressure. As the mutations spread concurrently through the population, they leave behind characteristic patterns of polymorphism near selected loci—so-called soft sweeps—which remain visible after adaptation is complete. These patterns are well-understood in two limits of the spreading dynamics of beneficial mutations: the panmictic case with complete absence of spatial structure, and spreading via short-ranged or diffusive dispersal events, which tessellates space into distinct compact regions each descended from a unique mutation. However, spreading behaviour in most natural populations is not exclusively panmictic or diffusive, but incorporates both short-range and long-range dispersal events. Here, we characterize the spatial patterns of soft sweeps driven by dispersal events whose jump distances are broadly distributed, using lattice-based simulations and scaling arguments. We find that mutant clones adopt a distinctive structure consisting of compact cores surrounded by fragmented “haloes” which mingle with haloes from other clones. As long-range dispersal becomes more prominent, the progression from diffusive to panmictic behaviour is marked by two transitions separating regimes with differing relative sizes of halo to core. We analyze the implications of the core-halo structure for the statistics of soft sweep detection in small genomic samples from the population, and find opposing effects of long-range dispersal on the expected diversity in global samples compared to local samples from geographic subregions of the range. We also discuss consequences of the standing genetic variation induced by the soft sweep on future adaptation and mixing.