Niches within a niche: ecological differentiation of subterranean amphipods across Europe’s interstitial waters

Species that successfully colonized subterranean environments are subject to two opposing selection processes. Stringent abiotic factors select for convergent adaptations, such as loss of eyes and pigments, while interspecific competition drives between-species divergence. Subterranean species can resolve opposing selection by adaptation to physically different microhabitats. Yet, species frequently co-occur in physically homogeneous subterranean habitats, like interstitial. These co-occurrences in such a narrow ecological context can be explained either by equalizing mechanisms, in which neither of the co-occurring species has a competitive advantage, or by more complex niche models that include species’ differentiation along a trophic niche axis. We tested these hypotheses using the amphipod genus Niphargus. We analysed Europe-wide co-occurrence records of Niphargus species from interstitial habitats, split into six independent large-scale regions. Firstly, we addressed whether specie...

成功定殖地下环境的物种会经受两种对立的选择进程。严苛的非生物因子会筛选出趋同适应性特征，例如视觉器官与色素的丢失；而种间竞争则会推动物种间的性状分化。地下物种可通过适应物理特性各异的微生境，来调和这一对立的选择压力。然而，物种常常会在物理性质均一的地下生境（如间隙生境（interstitial habitats））中共存。在这种狭窄的生态背景下的共存现象，可通过两类机制加以解释：其一为均衡机制（equalizing mechanisms），即共存的物种之间不存在竞争优势差异；其二为更复杂的生态位模型，该模型纳入了物种沿营养生态位轴的性状分化。我们以端足类（amphipod）钩虾属的泥钩虾属（Niphargus）为研究类群，对上述假说进行了检验。我们分析了欧洲范围内间隙生境中泥钩虾属物种的共存记录，并将其划分为6个独立的大尺度区域。首先，我们探究了物种……