Can Environment Predict Cryptic Diversity? The Case of Niphargus Inhabiting Western Carpathian Groundwater

In the last decade, several studies have shown that subterranean aquatic habitats harbor cryptic species with restricted geographic ranges, frequently occurring as isolated populations. Previous studies on aquatic subterranean species have implied that habitat heterogeneity can promote speciation and that speciation events can be predicted from species’ distributions. We tested the prediction that species distributed across different drainage systems and karst sectors comprise sets of distinct species. Amphipods from the genus Niphargus from 11 caves distributed along the Western Carpathians (Romania) were investigated using three independent molecular markers (COI, H3 and 28S). The results showed that: 1) the studied populations belong to eight different species that derive from two phylogenetically unrelated Niphargus clades; 2) narrow endemic species in fact comprise complexes of morphologically similar species that are indistinguishable without using a molecular approach. The concept of monophyly, concordance between mitochondrial and nuclear DNA, and the value of patristic distances were used as species delimitation criteria. The concept of cryptic species is discussed within the framework of the present work and the contribution of these species to regional biodiversity is also addressed.

近十年来，多项研究表明，地下水生栖息地栖息着地理分布范围受限的隐存种（cryptic species），且这些类群常以孤立种群的形式存在。既往针对地下水生类群的研究表明，生境异质性可推动物种形成，且物种形成事件可通过物种分布情况进行预测。我们验证了这一预测：分布于不同流域系统与喀斯特（karst）区域的类群，实为多个独立物种的集合。本研究以罗马尼亚西喀尔巴阡山脉沿线11个洞穴中的钩虾属（Niphargus）端足类为研究对象，采用3种独立分子标记（COI、H3及28S）开展分析。研究结果显示：1）本次研究的种群隶属于8个不同的物种，均起源于两个系统发育关系互不相关的钩虾属演化支；2）狭域特有种实际上是由多个形态相似的物种组成的复合类群，若不借助分子手段则无法对其进行区分。本研究以单系群（monophyly）概念、线粒体DNA与核DNA的一致性，以及支系距离（patristic distances）数值作为物种界定标准。本研究还在研究框架内探讨了隐存种的概念，并分析了这类物种对区域生物多样性的贡献。