Data from: Geographical and temporal dynamics of a global radiation and diversification in the killer whale

Global climate change during the Late Pleistocene periodically encroached and then released habitat during the glacial cycles, causing range expansions and contractions in some species. These dynamics have played a major role in geographic radiations, diversification and speciation. We investigate these dynamics in the most widely distributed of marine mammals, the killer whale (Orcinus orca), using a global dataset of over 450 samples. This marine top predator inhabits coastal and pelagic ecosystems ranging from the ice edge to the tropics, often exhibiting ecological, behavioral and morphological variation suggestive of local adaptation accompanied by reproductive isolation. Results suggest a rapid global radiation occurred over the last 350,000 years. Based on habitat models, we estimated there was only a 15% global contraction of core suitable habitat during the Last Glacial Maximum, and the resources appeared to sustain a constant global effective female population size throughout the Late Pleistocene. Reconstruction of the ancestral phylogeography highlighted the high mobility of this species, identifying 22 strongly supported long-range dispersal events including inter-oceanic and inter-hemispheric movement. Despite this propensity for geographic dispersal, the increased sampling of this study uncovered very few potential examples of ancestral dispersal among ecotypes. Concordance of nuclear and mitochondrial data further confirm genetic cohesiveness, with little or no current gene flow among sympatric ecotypes. Taken as a whole, our data suggest that the glacial cycles influenced local populations in different ways, with no clear global pattern, but with secondary contact among lineages following long-range dispersal as a potential mechanism driving ecological diversification.

晚更新世（Late Pleistocene）期间的全球气候变化在冰期旋回中周期性地侵占并释放栖息地，导致部分物种的分布范围发生扩张与收缩。这类动态过程在物种的地理辐射演化、多样化与物种形成进程中扮演了核心角色。我们以分布最广泛的海洋哺乳动物——虎鲸（Orcinus orca）为研究对象，依托涵盖逾450份样本的全球数据集，对上述动态展开系统探究。这类海洋顶级捕食者栖息于从冰缘区至热带海域的沿岸与远洋生态系统中，常表现出暗示本地适应且伴随生殖隔离的生态、行为与形态变异。研究结果表明，过去35万年间全球范围内曾发生一次快速的辐射演化事件。基于栖息地模型分析，我们估算得出末次冰盛期（Last Glacial Maximum）时核心适宜栖息地的全球缩减幅度仅为15%，且整个晚更新世期间，全球有效雌性种群规模似乎始终保持稳定。祖先谱系地理学重建凸显了该物种极强的移动能力，共识别出22个得到强力支持的长距离扩散事件，其中包含跨洋与跨半球的迁移活动。尽管该物种具有地理扩散的倾向，但本研究通过扩大采样范围仅发现了极少数跨生态型的祖先扩散潜在案例。核基因与线粒体数据的一致性进一步验证了其遗传一致性，而同域生态型之间目前几乎不存在或仅存在极微量的基因流。综合来看，我们的数据显示冰期旋回对各地种群的影响存在显著差异，并未呈现统一的全球模式，但长距离扩散后不同谱系间的次生接触，或许是推动生态分化的潜在机制。