Seabirds inhabiting vast water masses provide numerous examples where opposing phenomena, such as natal and breeding philopatry vs. vagility have dug cryptic taxonomic boundaries among closely related taxa. The taxonomy of little shearwaters of the North Atlantic Ocean (Little–Audubon’s shearwater complex, Puffinus assimilis–lherminieri) still remains unclear, and complementary information on non-breeding distributions and at-sea behaviour becomes essential to unravel divergent local adaptations to specific habitats. Using miniaturized light-level geolocators from seven study areas in the North Atlantic, we evaluate the spatial and habitat segregation, estimate the timing of their key life-cycle events and describe the at-sea behaviour of three taxa of these little shearwaters year-round to distinguish ecological patterns and specializations that could ultimately unravel potential lineage divergences. We also assess morphometric data from birds that were breeding at each study area to further discuss potential adaptations to specific habitats. Our results show that, while birds from different taxa segregated in space and habitats, they share ecological plasticity, similar annual phenology and diel foraging behaviour. These ecological inconsistencies, while defining the evolutionary stressors faced by these taxa, do not suggest the existence of three Evolutionary Significant Units. However, they confirm the recent evolutionary divergence among the three little shearwaters of the North Atlantic.

中文翻译：

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密切相关类群的空间生态学：以北大西洋小海鸥复合体为例

栖息在巨大水体中的海鸟提供了许多例子，其中对立的现象，例如出生和繁殖的亲缘与变异，在密切相关的分类群中挖掘了神秘的分类边界。北大西洋小剪切水（Little-Audubon 剪切水复合体，Puffinus assimilis-lherminieri）的分类学仍然不清楚，关于非繁殖分布和海上行为的补充信息对于解开对特定栖息地的不同当地适应性至关重要。使用来自北大西洋七个研究区的微型光级地理定位器，我们评估了空间和栖息地隔离，估计它们关键生命周期事件的时间，并描述这些小剪水动物的三个类群全年的海上行为，以区分可能最终解开潜在谱系分歧的生态模式和专业化。我们还评估了在每个研究区域繁殖的鸟类的形态测量数据，以进一步讨论对特定栖息地的潜在适应性。我们的研究结果表明，虽然来自不同分类群的鸟类在空间和栖息地隔离，但它们共享生态可塑性、相似的年度物候和日常觅食行为。这些生态不一致，虽然定义了这些分类群面临的进化压力源，但并不表明存在三个进化重要单元。然而，他们证实了北大西洋三个小剪切水最近的进化分歧。