Do diversity patterns of the spring-inhabiting snail Bythinella (Gastropoda, Bythinellidae) on the Aegean Islands reflect geological history?

Abstract

To explain the origin of the differentiation of the spring-inhabiting fauna on an island system, this study focused on the Aegean Islands and the Bythinella snails as a model organism. We inferred the phylogeographic pattern of the Aegean Bythinella with two molecular markers, and compared the inferred pattern with the geological history of the region and the estimated levels of biodiversity of Bythinella in Greece. 95 sequences of COI and 60 of ITS-1 were obtained from samples collected from Andros, Crete, Naxos, Chios, Kithira, and western Turkey, and pooled with previously published sequences from continental Greece. Phylogenetic analysis based on the COI revealed seven new clades. On Crete, three distinct clades were identified. The estimated divergence time indicated that the geological history of the island, which was divided into smaller islands until 2-3 Mya, was most probably responsible for such high diversity. Bythinella populations inhabiting Turkey were distinct from the Aegean populations, and the divergence began after the Zanclean flood (5.3 Mya). Shell morphology and anatomy of reproductive organs confirmed that molecularly distinct clades were real entities. Biodiversity analysis revealed that, in addition to five previously known Bythinella hotspots, there is a sixth in central Greece.Keywords Origin and history of spring fauna Á Springs as ephemeral habitats Á mtDNA Á COI Á ITS-1 Á Morphology Á Phylogeography Á Biodiversity

Does the genetic structure of spring snail Bythinella (Caenogastropoda, Truncatelloidea) in Bulgaria reflect geological history?

“…The authors of the present paper discovered another Bythinella hotspot in central Greece (Szarowska et al 2015). Thus, all the hotspots occur in mountain areas, which strongly suggests, that this type of landscape is especially favourable for Bythinella .…”

A new species of Bythinella Moquin-Tandon, 1855 (Caenogastropoda: Truncatelloidea) from Naxos Island, Greece

“…On the other hand, species identification with DNA sequences is always certain, although species boundaries remain disputable, especially with one locus and small divergence. In the case of B. walensae, however, there are two loci, and the p-distances are high (szArowskA et al 2016). …”

“…Species boundaries in Bythinella are still unclear, despite hundreds of sequences now available in the GenBank (FAlniowski 1987, 1992, bicHAin et al 2007a, b, szArowskA & FAlniowski 2008, benke et al 2009, FAlniowski & szArowskA 2011, 2012, szArowskA et al 2016. The simple and highly variable morphology is not sufficient even for species determination, thus molecular data are necessary.…”

“…Morphological characters within the Truncatelloidea usually lack the states which are unique, or characteristic at least, the ranges of variation are nearly always wide and overlap between the species or even genera (e.g. FAlniowski 1987, szArowskA & FAlniowski 2008, FAlniowski & szArowskA 2011, FAlniowski et al 2012a, szArowskA et al 2016. On the other hand, species identification with DNA sequences is always certain, although species boundaries remain disputable, especially with one locus and small divergence.…”

“…Ten sequences of internal transcribed spacer ITS-1, GenBank numbers: KT353614-KT353615 from locality N01 (Aghio Kyriaki), and KT353616-KT353623 from the type locality N02 (Aria Pygi) (szArowskA et al 2016). Diagnosis.…”