Isolation and endemism in subterranean aquatic snails: unexpected case of Montenegrospeum bogici (Pe\u0161i\u0107 et Gl\xf6er, 2012) (Gastropoda: Truncatelloidea: Hydrobiidae)

Andrzej Falniowski,Brian Lewarne,Sebastian Hofman,Jozef Grego,Artur Osikowski,Vladimir Pešić,Aleksandra Rysiewska

doi:10.1007/s10750-021-04688-6

Abstract

The subterranean aquatic snails may serve as a model of endemism and isolation vs. migration in subterranean habitats. The aim of the present paper is to verify the hypothesis that subterranean aquatic snails can migrate through diverse subterranean habitats, applying four molecular markers as well as a RAPD technique and shell morphometry. They were used to estimate the differences and gene flow between populations of the hydrobiid subterranean aquatic species Montenegrospeum bogici, collected in the Dinaric karst region. Three molecularly distinct taxonomic units were distinguished. The mOTU B was found at single locality, mOTU C at two, but the mOTU A at ten localities, scattered along 236 km distance, at two of them in sympatry with either mOTU B or C. Within mOTU A, the estimated levels of the gene flow were high. The pairwise measures of genetic differentiation were statistically significantly associated with geographic distances between the populations. In general, neither the infinite-island model of interpopulation differentiation, expected for isolated populations, nor the stepping-stone one, but rather the isolation-by-distance model explained the observed pattern. Our results suggest that interstitial habitats provide ways of migration for the stygobiont M. bogici, as has been already suggested for other subterranean gastropods.

Highlights

The subterranean aquatic snails may serve as a model of endemism and isolation vs. migration in subterranean habitats
Our results suggest that interstitial habitats provide ways of migration for the stygobiont M. bogici, as has been already suggested for other subterranean gastropods
Of the approximately 20,000 worldwide described species of subterranean animals (Culver & Pipan, 2009), stygobionts and troglobionts, there are over 350 described species of stygobiont gastropods, with 97% of them, and over 50 genera representing the superfamily Truncatelloidea (‘‘Hydrobiidae s. lato’’ in Bernasconi & Riedel, 1994; Culver, 2012)

Summary

Introduction

The subterranean aquatic snails may serve as a model of endemism and isolation vs. migration in subterranean habitats. A relatively high species diversity of the subterranean snails could be expected, as the group is well preadapted to such an environment, as being nocturnal (or at least avoiding direct sunlight), opportunistic, ecologically (especially feeding) generalist animals, with well-developed mechano-sensory and/or chemosensory traits (Trajano & Cobolli, 2012). They are well adapted to food-limited habitats, since their sizerelated energy requirements are low, being four times lower than in fishes and salamanders, and more than twice lower than in arthropod detritivores (Poulson, 2012). The stygobiont gastropods (whose interstitial representatives hardly differ from the ones inhabiting caves) are known nearly only from taxonomic descriptions, mostly based on their shell morphology alone

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