Connectivity is a fundamental process driving the persistence of marine populations and their adaptation potential in response to environmental change. In this study, we analysed the population genetics of two morphologically highly similar deep-sea sponge clades (Phakellia hirondellei and the ‘Topsentia-and-Petromica’ clade, (hereafter referred to as ‘TaP clade’)) at three locations in the Cantabrian Sea and simultaneously assessed the corresponding host microbiome by 16S rRNA gene sequencing. A virtual particle tracking approach (Lagrangian modelling) was applied to assess oceanographic connectivity in the study area. We observed overall genetic uniformity for both sponge clades. Notably, subtle genetic differences were observed for sponges of the TaP clade and also their microbiomes between a canyon and bank location, < 100 km apart and with the same depth range. The Lagrangian model output suggests a strong retention of larvae in the study area with variable inter-annual connectivity via currents between the three sampling regions. We conclude that geologic features (canyons) and the prevailing ocean currents may dictate sponge holobiont connectivity and that differentiation can emerge even on small spatial scales.

连通性是一个基本过程，可驱动海洋人口的持久性及其适应环境变化的适应潜力。在这项研究中，我们分析了两个形态高度相似的深海海绵进化枝（Phakellia hirondellei）的种群遗传学。在坎塔布连海的三个位置上的“ Topsentia-and-Petromica”进化枝（以下称为“ TaP进化枝”），并通过16S rRNA基因测序同时评估了相应的宿主微生物组。虚拟粒子跟踪方法（拉格朗日建模）用于评估研究区域的海洋学连通性。我们观察到两个海绵进化枝的整体遗传均匀性。值得注意的是，在峡谷和河岸位置（相距<100 km，且深度范围相同）之间，观察到TaP进化枝海绵及其微生物群存在细微的遗传差异。拉格朗日模型的输出表明，通过三个采样区域之间的电流，幼虫在研究区内的保留力强，年际连通性可变。