A molecular test for cryptic diversity in ground water: how large are the ranges of macro‐stygobionts?

Abstract

SUMMARY1. Various groundwater habitats have exceptionally high levels of endemism caused by strong hydrographical isolation and low dispersal abilities of their inhabitants. More than 10% of macro-stygobiotic species nevertheless occupy relatively large ranges, measuring from some hundred to over 2000 km in length. These species represent a challenge because their distributions disregard hydrographical boundaries, and their means to disperse and maintain long-term gene flow are unknown. 2. Based on mitochondrial and nuclear gene sequences, we examined the phylogeographic structure of six formally recognised stygobiotic species (Niphargus virei, N. rhenorhodanensis, Troglocaris anophthalmus, T. hercegovinensis, Spelaeocaris pretneri, Proteus anguinus) and searched for cryptic lineage diversity in a genus-wide phylogeny of Niphargus. Using treebased criteria as well as comparative divergence measures, we identified cryptic lineages, which may tentatively be equated with cryptic species. 3. Fourteen analysed nominal stygobiotic species with large ranges emerged as highly diversified, splitting into 51 tentative cryptic lineages. The degree of divergence was within the range or larger than the divergence of other related pairs of sister species. A substantial part (94%) of the cryptic lineages had ranges <200 km in length. One half of them were recorded at single sites only. The largest range recorded was that of a cryptic N. virei lineage (700 km), while none of the very large traditional ranges (e.g. Niphargus aquilex -2300 km, N. tauri -1900 km) could be corroborated. 4. These data suggest that small ranges of macro-stygobionts are the rule, and ranges over 200 km are extremely rare. 5. The implications of this result for groundwater biodiversity assessment and conservation include a considerable increase in overall diversity at the regional and continental scale and a strong decrease in faunal similarities among regions, coupled with greater endemism.

Origin of the interstitial isopod Microcharon (Crustacea, Microparasellidae) from the western Languedoc and the northern Pyrenees (France) with the description of two new species

“…According to Trontelj et al (2009), stygobiont ranges seem to "reflect historical rather than current hydrogeological conditions". Therefore, geological history is an important determinant of species richness.…”

“…A high level of endemism is one of the general patterns emerging in the outcome of the large-scale European survey of groundwater biodiversity in the framework of the European PAS-CALIS project . Trontelj et al (2009) states that this pronounced endemism "is caused by strong hydrographical isolation and low dispersal abilities of their inhabitants". Small ranges of stygobionts are the rule and "ranges over 200 km are extremely rare".…”

Distribution and a comparative analysis of the aquatic invertebrate fauna in caves of the western Caucasus

“…Recently, genetic analysis of the Niphargus genus revealed many cryptic species (Trontelj et al 2009). Most of these species have narrow local ranges, but about 25% of them have been found in caves 100 km or more apart (Lefébure et al 2006, Lefébure et al 2007, Trontelj et al 2009). The latter is peculiar to N. arbiter Karaman G., 1984, N. fontanus Bate, 1859, N. illidzensis cf.…”

Niche-based mechanisms operating within extreme habitats: a case study of subterranean amphipod communities

“…Convergent evolution is well documented for morphological [18], physiological and behavioural traits [19]. Furthermore, migration is constrained in subterranean habitats, high endemism and small ranges being the rule [20]. Finally, the inability to monopolize food resources might promote the coexistence of species [21].…”