Large-scale disturbance events provide ideal opportunities to directly study recolonisation processes in natural environments, via the removal of competitors and the formation of newly vacant habitat. A high magnitude earthquake in central New Zealand in 2016 created major ecological disturbance, with coastal tectonic uplift of up to ~ 6 m extirpating vast swathes of intertidal organisms. One of the affected species was Durvillaea antarctica (rimurapa or southern bull kelp), which is an important habitat-forming intertidal macroalga capable of long-distance dispersal. Across the complex fault system with varying amounts of uplift, the species was either locally extirpated or heavily reduced in abundance. We hypothesised that neutral priority effects and chance dispersal from other populations would influence which lineages would establish. We sampled individuals of D. antarctica across the uplift zone immediately after the earthquake in 2016 and then repeatedly sampled new recruits in the same areas between 2017 and 2020, using genotyping-by-sequencing to provide ‘before' and ‘after' genomic comparisons. Our results revealed strong geographic clustering but little evidence of new lineages establishing at disturbed sites, although populations at uplifted sites remain at remarkably low densities. We infer that recolonisation has thus far primarily originated from refugial, remnant patches within the uplift zone. To complement the phylogeographic analysis, we estimated oceanographic connectivity among the uplift zone sample locations. The connectivity modelling estimated that northbound dispersal of D. antarctica was more likely, but we have not yet detected southern genotypes in the recolonised populations. As the ongoing recolonisation process transitions from an ecological to an evolutionary timescale, change remains possible. This study provides the first genomic ‘snapshots' of a natural recolonisation process following a large-scale ecological disturbance event, and ongoing research has the potential to reveal important insight into both micro- and macroevolutionary processes.

中文翻译：

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毁灭性地震后重新殖民谱系的首个基因组快照


大规模干扰事件通过消除竞争者和形成新的空置栖息地，为直接研究自然环境中的再殖民过程提供了理想的机会。 2016 年新西兰中部发生的一场高强度地震造成了严重的生态扰动，海岸构造抬升高达约 6 m，消灭了大片潮间带生物。受影响的物种之一是 Durvillaea antarctica（rimurapa 或南方巨藻），它是一种重要的形成栖息地的潮间带大型藻类，能够长距离扩散。在具有不同程度隆升的复杂断层系统中，该物种要么局部灭绝，要么数量大幅减少。我们假设中性优先效应和来自其他种群的机会扩散会影响建立哪些谱系。我们在 2016 年地震发生后立即对隆起区的南极洲 D. antarctica 个体进行了采样，然后在 2017 年至 2020 年间对同一地区的新补充个体进行了重复采样，利用测序基因分型来提供“之前”和“之后”的基因组比较。我们的结果显示了强烈的地理集群，但几乎没有证据表明新的谱系在受干扰的地点建立，尽管隆起地点的种群密度仍然非常低。我们推断，迄今为止，重新殖民化主要起源于隆起区内的避难残余斑块。为了补充系统地理学分析，我们估计了隆起区样本位置之间的海洋学连通性。连通性模型估计，D. antarctica 更有可能向北扩散，但我们尚未在重新殖民的种群中检测到南方基因型。 随着正在进行的重新殖民过程从生态时间尺度过渡到进化时间尺度，变化仍然是可能的。这项研究提供了大规模生态干扰事件后自然重新殖民过程的第一个基因组“快照”，正在进行的研究有可能揭示对微观和宏观进化过程的重要见解。