A Complex System of Glacial Sub-Refugia Drives Endemic Freshwater Biodiversity on the Tibetan Plateau

• Published in: PloS one 2016-08, Vol.11 (8), p.e0160286-e0160286
• Main Authors: Clewing, Catharina, Albrecht, Christian, Wilke, Thomas
• Format: Article
• Language: English
• Subjects: Amplified fragment length polymorphism; Amplified Fragment Length Polymorphism Analysis - methods; Analysis; Animals; Aquatic ecosystems; Bayes Theorem; Biodiversity; Biology and Life Sciences; Cladistic analysis; Clustering; Data processing; Demographics; Deoxyribonucleic acid; DNA; DNA, Mitochondrial - genetics; Drainage; Drainage systems; Earth Sciences; Ecology; Ecology and Environmental Sciences; Ecosystem; Ecosystems; Endemism; Evolution; Evolution, Molecular; Freshwater Biology; Freshwater invertebrates; Genetics, Population; Genotypes; Glacial lakes; Glaciers; High altitude; High-altitude environments; Lakes; Last Glacial Maximum; Mitochondrial DNA; People and Places; Permafrost; Phylogenetics; Phylogeny; Phylogeography; Pleistocene; Ponds; Population Dynamics; Populations; Refugia; Regional analysis; Research and Analysis Methods; Sequence Analysis, DNA - methods; Snails; Snails - genetics; Spatial distribution; Studies; Taxa; Tibet; Water springs; Watersheds; Wetlands
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0160286

Although only relatively few freshwater invertebrate families are reported from the Tibetan Plateau, the degree of endemism may be high. Many endemic lineages occur within permafrost areas, raising questions about the existence of isolated intra-plateau glacial refugia. Moreover, if such refugia existed, it might be instructive to learn whether they were associated with lakes or with more dynamic ecosystems such as ponds, wetlands, or springs. To study these hypotheses, we used pulmonate snails of the plateau-wide distributed genus Radix as model group and the Lake Donggi Cona drainage system, located in the north-eastern part of the plateau, as model site. First, we performed plateau-wide phylogenetic analyses using mtDNA data to assess the overall relationships of Radix populations inhabiting the Lake Donggi Cona system for revealing refugial lineages. We then conducted regional phylogeographical analyses applying a combination of mtDNA and nuclear AFLP markers to infer the local structure and demographic history of the most abundant endemic Radix clade for identifying location and type of (sub-)refugia within the drainage system. Our phylogenetic analysis showed a high diversity of Radix lineages in the Lake Donggi Cona system. Subsequent phylogeographical analyses of the most abundant endemic clade indicated a habitat-related clustering of genotypes and several Late Pleistocene spatial/demographic expansion events. The most parsimonious explanation for these patterns would be a scenario of an intra-plateau glacial refugium in the Lake Donggi Cona drainage system, which might have consisted of isolated sub-refugia. Though the underlying processes remain unknown, an initial separation of lake and watershed populations could have been triggered by lake-level fluctuations before and during the Last Glacial Maximum. This study inferred the first intra-plateau refugium for freshwater animals on the Tibetan Plateau. It thus sheds new light on the evolutionary history of its endemic taxa and provides important insights into the complex refugial history of a high-altitude ecosystem.