Survival and differentiation of subspecies of the land snailCharpentieria italain mountain refuges in the Southern Alps

The Bayesian lens and Bayesian blinkers

I discuss the benefits of looking through the 'Bayesian lens' (seeking a Bayesian interpretation of ostensibly non-Bayesian methods), and the dangers of wearing 'Bayesian blinkers' (eschewing non-Bayesian methods as a matter of philosophical principle). I hope that the ideas may be useful to scientists trying to understand widely used statistical methods (including confidence intervals and [Formula: see text]-values), as well as teachers of statistics and practitioners who wish to avoid the mistake of overemphasizing philosophy at the expense of practical matters. This article is part of the theme issue 'Bayesian inference: challenges, perspectives, and prospects'.

Speciation of rock-dwelling snail species: disjunct ranges and mosaic patterns reveal the importance of long-distance dispersal in Chilostoma (Cingulifera) in the European Southern Alps

To better understand the origin of the high diversity and endemism in the Southern Alps of Europe, we investigated the phylogeny and population structure of the rock-dwelling snail group Chilostoma (Cingulifera) in the Southern Alps. We generated genomic ddRAD data and mitochondrial sequences of 104 Cingulifera specimens from 28 populations and 14 other Ariantinae. Until recently, about 30 Cingulifera taxa were classified as subspecies of a single polytypic species. The phylogenetic and population genetic analyses of the ddRAD data and mitochondrial sequences revealed that Cingulifera in the Southern Alps is differentiated into three species. Each of the three Chilostoma (Cingulifera) species occupies disjunct sub-areas, which are separated by areas occupied by other Chilostoma taxa. Neighbouring populations of different species show little or no admixture. Tests indicating that the genetic differentiation of the three Cingulifera taxa cannot be explained by isolation by distance confirmed their species status. The disjunct range patterns demonstrate the importance of stochastic events such as passive long-distance dispersal for the evolution of population structure and speciation in these snails, and of priority effects and ecological competition as important factors influencing species distributions.

Phylogeny and evolution of the land snail tribe Clausiliini (Gastropoda: Clausiliidae)

The phylogenetic relationships within the land snail group Clausiliini were analysed based on an almost complete taxon sampling (28 of 29 extant species) and a set of mitochondrial and nuclear markers. The phylogenetic analyses and character state reconstructions revealed several trends in the group that resulted in repeated convergences. The N-type closing apparatus was convergently transformed into a G-type clausilial apparatus in Graciliaria, Ruthenica + Micridyla and probably three times within Neostyriaca. There were parallel changes in the length of the male copulatory organs and repeated reductions of the basal keel in several lineages. Such trends resulting in repeated convergences are characteristic for several radiations of stylommatophoran land snails. They may reflect parallel adaptations of related lineages to similar environmental constraints. However, it is also possible that some of these transformations are not adaptive, but represent random changes in a restricted morphospace. We explored the timing of the Clausiliini radiation using different calibration strategies. Despite large numbers of fossils of Clausiliidae from Western and Central Europe, the results of these analyses and the fossil evidence for a Cretaceous origin of the Clausiliidae indicate that there are large gaps in the fossil record of the Clausiliini. Especially the origin and early evolution of the Clausiliini in Southeastern Europe is obscured by our insufficient knowledge of Neogene deposits there.

The introduction of the European Caucasotachea vindobonensis (Gastropoda: Helicidae) in North America, its origin and its potential range

We report the introduction of the central and eastern European helicid land snail Caucasotachea vindobonensis in North America. It was first recorded from Rensselaer County in the state of New York in 2015 by a community scientist. From 2016 to 2020, 14 additional occurrences in Rensselaer County, neighbouring Albany County and an imprecisely localized site in the Adirondack Mountains were recorded by community scientists. In 2020, the species was newly recorded at two sites in Schoharie County, NY, and at three sites in Québec, one of them approximately 700 km to the north of the initial record. Partial mitochondrial cox1 sequences from Rensselaer differ from an eastern Ukrainian haplotype only in a single substitution. Therefore, a Ukrainian origin for this introduction is likely, although not certain: the Rensselaer haplotype also differs in only two substitutions from a more widespread haplotype known from Ukraine, Hungary, Slovakia, Czechia, Serbia, and Bulgaria. An environmental niche model of the species based on occurrence data from central and eastern Europe indicated that a large region from the northern east coast to the midwestern United States is suitable for C. vindobonensis. The Canadian occurrences may indicate that the North American lineage is able to survive colder winters than predicted by the environmental niche model. Caucasotachea vindobonensis is not listed as a pest in Europe and it is unlikely to become an agricultural pest in North America as it prefers rotting plant material over living parts of plants, but its impact on native organisms can hardly be predicted.

Evaluating Species Delimitation Methods in Radiations: The Land Snail Albinaria cretensis Complex on Crete

Delimiting species in radiations is notoriously difficult because of the small differences between the incipient species, the star-like tree with short branches between species, incomplete lineage sorting, and the possibility of introgression between several of the incipient species. Next generation sequencing data may help to overcome some of these problems. We evaluated methods for species delimitation based on genome-wide markers in a land snail radiation on Crete. Species delimitation in the Albinaria cretensis group was based exclusively on shell characters until now and resulted in classifications distinguishing 3-9 species. We generated sequences of 4270 loci for 140 specimens of the Albinaria cretensis group from 48 populations by double-digest restriction site-associated DNA sequencing. We evaluated three methods for species discovery. The multispecies coalescent approach implemented in the program Bayesian Phylogenetics and Phylogeography resulted in a drastic overestimating of the number of species, whereas Gaussian clustering resulted in an overlumping. Primary species hypotheses based on the maximum percentage of the genome of the individuals derived from ancestral populations as estimated with the program ADMIXTURE moderately overestimated the number of species, but this was the only approach that provided information about gene flow between groups. Two of the methods for species validation that we applied, BFD* and delimitR, resulted in an acceptance of almost all primary species hypotheses, even such based on arbitrary subdivisions of hypotheses based on ADMIXTURE. In contrast, secondary species hypotheses, resulting from an evaluation of primary species hypotheses based on ADMIXTURE with isolation by distance tests, approached the morphological classification, but also uncovered two cryptic species and indicated that some of the previously delimited units should be combined. Thus, we recommend this combination of approaches that provided more detailed insights in the distinctness of barriers between the taxa of a species complex and the spatial distribution of admixture between them than the other methods. The recognition and delimitation of undersampled species remained a major challenge.

Incorporating palaeogeography into ancestral area estimation can explain the disjunct distribution of land snails in Macaronesia and the Balearic Islands (Helicidae: Allognathini)

The systematics and biogeographical history of the Eastern Mediterranean and Macaronesian land snail tribe Allognathini (Helicidae: Helicinae) is investigated based on mitochondrial and nuclear DNA sequence data. Our molecular phylogenetic analyses indicate that the genus-group systematics of the tribe needs to be revised. We show for the first time that the narrow-range endemics Lampadia and Idiomela from the Madeira Archipelago belong to Allognathini and represent together the sister group of the diverse Canary Island Hemicycla radiation. We therefore suggest synonymising Lampadiini with Allognathini. Sister to these Macaronesian genera was the Balearic Island Allognathus radiation. Pseudotachea was not recovered as a monophyletic group and the two currently recognised species clustered in Iberus. Similarly, Adiverticula was not recovered as a monophyletic group and clustered in Hemicycla. We therefore suggest synonymising Pseudotachea with Iberus and Adiverticula with Hemicycla. The six genera in Allognathini, which we distinguish here (Cepaea, Iberus, Allognathus, Hemicycla, Idiomela and Lampadia), originated in Western to South-western Europe according to our ancestral area estimation and the fossil record. The disjunct distribution of the Balearic Islands and Macaronesian sister clades and the mainly Iberian Iberus clade that separated earlier can be explained by the separation of the Betic-Rif System from the Iberian Peninsula during the late Oligocene to early Miocene, along with independent Miocene dispersals to the Balearic Islands and Macaronesia from the Iberian Peninsula, where the ancestral lineage became extinct.

One, two or three? Integrative species delimitation of short-range endemic Hemicycla species (Gastropoda: Helicidae) from the Canary Islands based on morphology, barcoding, AFLP and ddRADseq data

Hemicycla mascaensis and H. diegoi are short-range endemics that occur allopatrically in small areas in the Teno Mountains in the western part of Tenerife (Canary Islands). Both taxa have been recognised as distinct species based on differences in shell morphology and genital anatomy. Preliminary molecular analyses using mitochondrial markers suggested a potential paraphyly of H. diegoi with regard to H. mascaensis. We here use multilocus AFLP data and ddRADseq data as well as distribution data, data on shell morphology and genital anatomy to assess the status of these taxa using phylogenetic analyses, species tree reconstruction and molecular species delimitation based on the multispecies coalescent as implemented in BFD* and BPP in an integrative approach. Our analyses show that, based on the analysis of multilocus data, the two taxa are reciprocally monophyletic. Species delimitation methods, however, tend to recognise all investigated populations as distinct species, albeit neither lending unambiguous support to any of the species hypotheses. The comparison of the anatomy of distal genital organs further suggests differentiation within H. mascaensis. This highlights the need for a balanced weighting of arguments from different lines of evidence to determine species status and calls for cautious interpretations of the results of molecular species delimitation analyses, especially in organisms with low active dispersal capacities and expected distinct population structuring such as land snails. Taking all available evidence into account, we favour to recognise H. mascaensis and H. diegoi as distinct species, acknowledging, though, that the recognition of both taxa as subspecies (with possibly a third yet undescribed) would also be an option as morphological differentiation is within the limits of other land snail species that are traditionally subdivided into subspecies.

Phylogeny, species delimitation and population structure of the steppe-inhabiting land snail genus Helicopsis in Eastern Europe

We here study the steppe-inhabiting land snail genus Helicopsis (Gastropoda: Geomitridae: Helicellinae) across Eastern Europe using mitochondrial 16S rDNA sequences and nuclear AFLP markers and compare the biogeographical patterns with those of other steppe-inhabiting organisms. The subdivision of Central and Eastern European Helicopsis reflects the geographical subdivision of the European steppe belt in Pontic, Pannonian and Northern steppes. The subdivision within Helicopsis is deeper, at the species level, than in most other steppe-inhabiting groups. Helicopsis populations from the Pontic steppes can be classified into two sister-species. Helicopsis lunulata includes mainly populations with depressed conical shells previously identified as H. striata, but also populations with disc-like shells previously identified as H. instabilis, and it is distributed mainly west of the Dnieper River. Most Helicopsis populations from east of the Dnieper, especially from Crimea, belong to the variable H. filimargo that includes H. gasprensis, H. retowskii, H. arenosa, H. luganica, H. martynovi and H. subfilimargo. The species inhabiting the Pannonian Basin and the Northern steppes form a well-supported monophylum, including H. hungarica in the Pannonian Basin, H. austriaca at the fringe of the Eastern Alps and H. striata mainly in the Northern steppes.

Repeated hybridization increased diversity in the door snail complex Charpentieria itala in the Southern Alps

The door snail species complex Charpentieria itala is widely distributed in the Southern Alps and subdivided into several morphologically differentiated subspecies. Thus, it can be used as a model group for understanding migration and differentiation processes in the Southern Alps. We generated genome-wide double digest Restriction Site Associated DNA (ddRAD) sequencing data for 166 specimens from 36 populations of the door snail Charpentieria itala and for 8 specimens of the other three Charpentieria species to reconstruct their evolutionary history and phylogeography. Phylogenetic and structure analyses based on the ddRAD data indicated that the repeated separation of the populations in western and eastern groups by the Garda glacier during the glacials was the process that most strongly shaped the population structure of C. itala. This process may also explain a similar phylogeographic boundary in many other southern Alpine animal and plant species. Our study revealed that some populations that resemble Charpentieria stenzii morphologically and ecologically, the 'stenzioid' subspecies, originated by a hybridization event with Charpentieria stenzii. A further hybridization event between stenzioid populations that survived the glacials in mountain refuges and non-stenzioid populations that probably came into contact with stenzioid populations as a result of climate warming during an interglacial resulted in the origin of a hybrid subspecies that is adapted to intermediate altitudes. Our study demonstrated that the origin of new differentiated taxa by hybridization, is more frequent than previously assumed.

A Sicilian–Cretan biogeographical disjunction in the land snail genus Cornu (Gastropoda: Helicidae)

We report an unusual biogeographical disjunction between the western and the eastern Mediterranean region. Cornu (Gastropoda: Helicidae) is a western Mediterranean land snail genus. It includes Cornu (Cornu) aspersum, which originated in north-western Africa and was distributed by humans for food or accidentally, first throughout the Mediterranean region and, subsequently, to all continents except Antarctica. It also includes three species belonging to the subgenus Erctella, which are all endemic to Sicily. We discovered a new species of Cornu on the Greek island of Crete. The morphological and molecular genetic analyses showed that the species from Crete is a disjunct representative of the subgenus Erctella. We hypothesize that the disjunction originated by a long-distance dispersal event of the ancestors of the Cretan species from Sicily by birds or by sea currents, perhaps facilitated by a tsunami or a similar event. The Cretan lineage separated from the Sicilian species in the Late Miocene or Early Pliocene. This divergence time is compatible with the hypothesis that the ancestor of Cornu cretense sp. nov. was washed from Sicily to Crete by the Zanclean flood that refilled the Mediterranean basin after it had dried up during the Messinian salinity crisis.

One species, two developmental modes: a case of geographic poecilogony in marine gastropods

Background

Poecilogony, the presence of two developmental modes in the same animal species, is a rare phenomenon. Few cases of poecilogony have been suggested for marine invertebrates including molluscs and even less stood extensive testing, mostly revealing a species pair with differing developmental modes. We studied a textbook example of poecilogony in the viviparous snail Planaxis sulcatus (Gastropoda: Planaxidae), for the first time throughout its entire distribution range.

Results

In the Western Indian Ocean and Red Sea this intertidal species is observed to have large, shelled juveniles, whereas in the Indo-West Pacific planktotrophic veliger larvae are released from a subhaemocoelic brood pouch. We uncovered a shift in developmental modes across its range: from west to east successively earlier developmental stages are released. Furthermore, genetic data based on mitochondrial DNA suggests to recognize P. sulcatus as a single species rather than a group of cryptic species. A reconstruction of the ancestral area of P. sulcatus based on molecular data outlines the Western Indian Ocean and the Indo-West Pacific as area of origin.

Conclusion

The findings supporting Planaxis sulcatus as a single widespread species and the geographical shift from one reproductive mode to another suggest for this species to truly represent a case of geographic poecilogony, i.e. differing developmental modes between populations of the same species. Furthermore, the results of our ancestral range estimation imply the release of planktotrophic larvae as the ancestral developmental mode.

Phylogenetic relationships of ghost slugs (Selenochlamys) and overlooked instances of limacization in Western Palaearctic Limacoidei (Gastropoda: Stylommatophora)

We analysed the phylogenetic relationships of the enigmatic ghost slug Selenochlamys with other Western Palaearctic Limacoidei based on mitochondrial and nuclear sequences. Selenochlamys is a carnivorous slug group from the Caucasus region. Until now, it has been classified in Trigonochlamydidae, which includes several carnivorous slug groups from the Caucasus region. However, the molecular phylogenetic analyses revealed that Selenochlamys originated from omnivorous snails belonging to Oxychilidae. The similarities of Selenochlamys and Trigonochlamydidae are convergences resulting from limacization, the evolutionary transition from shelled snails to slugs, and from the transition from herbivory or detritivory via omnivory to obligate carnivory. These two evolutionary trends occurred repeatedly within the Limacoidei. Phylogenetic analyses based on morphological characters are prone to underestimate the instances with which such recurrent evolutionary trends occurred, as they depend on the parsimony criterion. The molecular phylogenetic analyses revealed that Limacoidea and Parmacelloidea, which were at least partly based on characters associated with limacization, are polyphyletic. The molecular phylogenetic tree implied that 5-7 independent limacizations occurred in the Western Palaearctic Limacoidei. Half of these limacizations remained undetected in a previous parsimony analysis based on morphological characters. Moreover, the analyses revealed that Godwiniinae belong to Gastrodontidae, not Oxychilidae.

The effect of landscape on functional connectivity and shell shape in the land snail Humboldtiana durangoensis

The populations of Humboldtiana durangoensis have experienced a drastic reduction in the effective population size; in addition, the species is threatened by anthropogenic activities. For the aforementioned, landscape genetics will serve as a tool to define the potential evolutionarily significant units (ESU) for this species. To complete our objective, we evaluated the effect of cover vegetation and climate on the functional connectivity of the species from the last glacial maximum (LGM) to the present as well as the effect of climate on shell shape. Partial Mantel tests, distance-based redundance analysis and a Bayesian framework were used to evaluate connectivity. On the other hand, geometric morphometrics, phylogenetic principal component analysis and redundancy analysis were used for the analysis of shell shape. Our results suggest that the suitable areas have been decreasing since the LGM; also, vegetation cover rather than climate has influenced the genetic connectivity among land snail populations, although temperature had a high influence on shell shape in this species. In conclusion, vegetation cover was the main factor that determined the functional connectivity for the land snail; however, local selective pressures led to different phenotypes in shell shape that allowed us to postulate that each one of the previously defined genetic groups must be considered as a different ESU.

Ecological specialization resulting in restricted gene flow promotes differentiation in door snails

We tested the hypothesis that ecological specialization that affects dispersal promotes diversification by a comparison of the genetic structure of two sister species of door snails across their broadly overlapping ranges in the Crimean Mountains. The hypothesized effect of ecological specialization on diversification is supported by STRUCTURE analyses that showed that Mentissa gracilicosta that is restricted to limestone rocks, is subdivided into several distinct clusters, whereas all populations of the species adapted to more continuous habitat, the forests-dwelling Mentissa canalifera, were assigned to a single cluster. Furthermore, it is supported by AMOVAs that showed that a larger part of the genetic variation of M. gracilicosta is apportioned among populations than in M. canalifera. The stronger genetic differentiation of the M. gracilicosta populations corresponds to their more distinct morphological differentiation that resulted in the classification of M. gracilicosta into several geographical subspecies, whereas the more continuously distributed M. canalifera was not subdivided into subspecies. The stronger differentiation of populations of M. gracilicosta compared to M. canalifera can be ascribed to reduced gene flow between the isolated populations of M. gracilicosta and to founder events associated with the long distance dispersal events that are necessary for the colonization of isolated rocks by M. gracilicosta. In Central Europe, the Pleistocene climatic oscillations selected for species with high dispersal abilities, whereas the more stable climate in southern Europe facilitated the non-adaptive radiation of rock-dwelling door snails. Thus, the intrinsic ecological properties of these species groups contributed to the latitudinal diversity gradient.

Exploration of phylogeography of Monachacantiana s.l. continues: the populations of the Apuan Alps (NW Tuscany, Italy) (Eupulmonata, Stylommatophora, Hygromiidae)

Two new lineages CAN-5 and CAN-6 were recognised in four populations of Monachacantiana (Montagu, 1803) s.l. from the Italian Apuan Alps by joint molecular and morphological analysis. They are different from other M.cantiana lineages known from English, Italian, Austrian and French populations, i.e. CAN-1, CAN-2, CAN-3 and CAN-4, as well as from the other Italian Monacha species used for comparisons (M.parumcincta and M.cartusiana). Although a definite taxonomic and nomenclatural setting seems to be premature, we suggest that the name or names for these new lineages as one or two species should be found among 19th century names (Helixsobara Mabille, 1881, H.ardesa Mabille, 1881, H.apuanica Mabille, 1881, H.carfaniensis De Stefani, 1883 and H.spallanzanii De Stefani, 1884).

Revision of the genus-group Hystricella R. T. Lowe, 1855 from Porto Santo (Madeira Archipelago), with descriptions of new recent and fossil taxa (Gastropoda, Helicoidea, Geomitridae)

The genus-group Hystricella R. T. Lowe, 1855 is revised on the basis of conchological, anatomical and genetic characteristics. A new genus Wollastoniagen. n., two recent species, W.jessicaesp. n. and W.klausgrohisp. n., and one recent subspecies, W.jessicaemonticolassp. n. are described as new to science, as well as five fossil taxa, H.microcarinatasp. n., W.beckmannisp. n., W.falknerorumsp. n., W.ripkenisp. n., and W.inexpectatasp. n. For Helixvermetiformis R. T. Lowe, 1855, H.leacockiana Wollaston, 1878, H.oxytropis R. T. Lowe, 1831, H.duplicata R. T. Lowe, 1831 and H.oxytropisvar.ßsubcarinulata Wollaston, 1878 lectotypes are designated. For the taxa Helixbicarinata G. B. Sowerby I, 1824, Helixbicarinatavar.ßaucta Wollaston, 1878 and Disculabulverii W. Wood, 1828 neotypes are selected. The taxa aucta and subcarinulata are elevated to specific rank. For the hitherto monospecific (sub-) genus Callina R. T. Lowe, 1855 it is shown that it is not closely related to the genus Discula but to the Hystricella-group and its generic rank is confirmed. The taxon D.bulverii W. Wood, 1828 is transferred from the genus Discula s. str. to the genus Callina. A further fossil taxon C.waldenisp. n. is described as new to science.

Snails in the desert: Species diversification of Theba (Gastropoda: Helicidae) along the Atlantic coast of NW Africa

The spatial subdivision of species often plays a pivotal role in speciation. Across their entire range, species are rarely panmictic and crucial consequences of spatial subdivision are (1) random genetic drift including historical factors, (2) uniform selection, and (3) divergent selection. Each of these consequences may result in geographic variation and eventually reproductive isolation, but their relative importance in speciation is still unclear. In this study, we used a combination of genetic, morphological, and climatic data to obtain a comprehensive picture of differentiation among three closely related, parapatrically distributed taxa of the land snail genus Theba occurring along the Atlantic coasts of South Morocco and Western Sahara. We conducted Mantel and partial Mantel tests to relate phenotypic and genotypic variation of these species to geography and/or climate. As null hypothesis for an evolutionary scenario, we assumed nonadaptive speciation and expected a pattern of isolation by distance among taxa. Rejection of the null hypothesis would indicate isolation by environment due to adaptation. Generally, genetic drift plays an important role but is rarely considered as sole driver of speciation. It is the combination of drift and selection that predominantly drives speciation. This study, however, provides a potential example, in which nonadaptive speciation, that is, genetic drift, is apparently the main driver of shaping the diversity of Theba in NW Africa. Restriction of gene flow between populations caused by geographic isolation probably has played an important role. Climate oscillations during the Plio- and Pleistocene may have led to repeated ecological changes in NW Africa and disruptions of habitats promoting differentiation by geographic isolation. The inferred evolutionary scenario, however, did not fully explain the incongruence between the AFLP- and mtDNA-tree topologies. This incongruence might indicate past hybridization among the studied Theba forms.

First establishment of microsatellite markers in clausiliid snails (Mollusca: Gastropoda: Clausiliidae)

Background

Clausiliidae (door snails) are gastropods with a very high diversity concerning shell morphology, especially of their complex closing apparatus, which provides the most important diagnostic traits for classification of taxa. Due to the high variability, a high number of taxa has been described, though their systematics and taxonomy is partially controversially discussed. Montenegrina is the second most speciose door snail genus in Europe. It is an obligate rock-dwelling land snail and has, compared to its complex systematics, a rather small distribution range in the western parts of the Balkan Peninsula. The different taxa themselves show a very narrow and patchy distribution range. As Montenegrina is comprehensively sampled over the whole distribution range, it is a perfect study system for general questions on speciation and morphological differentiation in land snails. To study the amount of gene flow between geographically close or co-occurring populations, highly polymorphic markers are needed.

Results

Thirteen microsatellite loci with a tetranucleotid repeat were isolated and tested in three geographically close Montenegrina populations (two populations of M. dofleini prespaensis from the Prespa Lake, n = 35 and one population from M. stankovici from the Ohrid Lake, n = 20). The number of alleles per locus ranged from 2 to 27. No significant linkage disequilibria between the same two loci were found in all three tested populations. The deviation from Hardy–Weinberg equilibrium reveal only for two loci a significant deviation from HWE in more than one population (Mont_5483 and Mont_4477).

Conclusion

The 13 newly established genetic markers will help to gain better insights to the population genetic structure of Montenegrina and might reveal new results about speciation processes in co-occurring taxa. Furthermore, these microsatellite loci could also be tested in other clausiliid species.

Taxonomic revision of the rock-dwelling door snail genus Montenegrina Boettger, 1877 (Mollusca, Gastropoda, Clausiliidae)

The genus Montenegrina is revised on the basis of material available at the Hungarian Natural History Museum (Budapest), Naturhistorisches Museum Wien (Vienna), and the Naturmuseum Senckenberg (Frankfurt am Main), as well as newly discovered populations. The following new taxa are described: Montenegrina haringae sp. n., Montenegrina lillae sp. n., Montenegrina prokletiana sp. n., Montenegrina sturanyana sp. n., Montenegrina grammica erosszoltani ssp. n., Montenegrina grammica improvisa ssp. n., Montenegrina hiltrudae desaretica ssp. n., Montenegrina hiltrudae selcensis ssp. n., Montenegrina laxa delii ssp. n., Montenegrina nana barinai ssp. n., Montenegrina prokletiana kovacsorum ssp. n., Montenegrina rugilabris golikutensis ssp. n., Montenegrina rugilabris gregoi ssp. n., Montenegrina skipetarica danyii ssp. n., Montenegrina skipetarica gurelurensis ssp. n., Montenegrina skipetarica pifkoi ssp. n., Montenegrina skipetarica puskasi ssp. n., Montenegrina sporadica tropojana ssp. n., Montenegrina sturanyana gropana ssp. n., Montenegrina sturanyana ostrovicensis ssp. n., and Montenegrina tomorosi hunyadii ssp. n. A neotype is designated for Montenegrina helvola (Küster, 1860), and Montenegrina cattaroensis antivaricostata nom. n. was introduced to replace the junior homonym Clausilia umbilicata costata Boettger, 1907 (non Pfeiffer, 1928). Of each taxon types or specimens from the type localities are figured, and distribution maps are provided.

Phylogeography of the land snail genus Orcula (Orculidae, Stylommatophora) with emphasis on the Eastern Alpine taxa: speciation, hybridization and morphological variation

BACKGROUND

The Central and Southern European mountain ranges represent important biodiversity hotspots and show high levels of endemism. In the land snail genus Orcula Held, 1837 nine species are distributed in the Alps and a few taxa inhabit the Carpathians, the Dinarids and the Western Black Sea region. In order to elucidate the general patterns of temporal and geographic diversification, mitochondrial and nuclear markers were analyzed in all 13 Orcula species. We particularly aimed to clarify whether the Alpine taxa represent a monophyletic group and if the local species diversity is rather the result of isolation in geographically separated Pleistocene glacial refuges or earlier Tertiary and Quaternary palaeogeographic events. In order to test if patterns of molecular genetic and morphological differentiation were congruent and/or if hybridization had occurred, shell morphometric investigations were performed on the Orcula species endemic to the Alps.

RESULTS

The phylogenetic trees resulting from the analyses of both the mitochondrial (COI, 12S and 16S) and the nuclear (H4/H3) data sets revealed three main groups, which correspond to the three subgenera Orcula, Illyriobanatica and Hausdorfia. The reconstruction of the historic geographic ranges suggested that the genus originated in the Dinarides during the Middle Miocene and first colonized the Alps during the Late Miocene, giving rise to the most diverse subgenus Orcula. Within the latter subgenus (including all Alpine endemics) almost all species were differentiated by both molecular genetic markers and by shell morphometrics, except O. gularis and O. pseudodolium.

CONCLUSIONS

The present study confirms the importance of the Alps as biodiversity hotspot and origin center of land snail diversity. The species diversity in the subgenus Orcula was likely promoted by Miocene to Pliocene palaeogeographic events and the insular distribution of preferred limestone areas. In some cases, speciation events could be linked to the divergence of populations in glacial refuges during the Pleistocene. Sporadic contact between geographically separated and reproductively not yet isolated populations led to intermixture of haplogroups within species and even hybridization and mitochondrial capture between species.

In search of glacial refuges of the land snail Orcula dolium (Pulmonata, Orculidae)--an integrative approach using DNA sequence and fossil data

Harboring a large number of endemic species, the Alps and the Western Carpathians are considered as major centers of biodiversity. Nonetheless, the general opinion until the turn of the millennium was that both Central European mountain regions did not provide suitable habitat during the Last Glacial Maximum, but were colonized later from southern refuges. However, recent molecular genetic studies provide new evidence for peripheral Alpine refuges. We studied the phylogeography of the calciphilous land snail O. dolium across its distribution in the Alps and the Western Carpathians to assess the amount of intraspecific differentiation and to detect potential glacial refuges. A partial sequence of the mitochondrial COI was analyzed in 373 specimens from 135 sampling sites, and for a subset of individuals, partial sequences of the mitochondrial 16S and the nuclear histone H3 and H4 were sequenced. A molecular clock analysis was combined with a reconstruction of the species' geographic range history to estimate how its lineages spread in the course of time. In order to obtain further information on the species' past distribution, we also screened its extensive Pleistocene fossil record. The reconstruction of geographic range history suggests that O. dolium is of Western Carpathian origin and diversified already around the Miocene-Pliocene boundary. The fossil record supports the species' presence at more than 40 sites during the last glacial and earlier cold periods, most of them in the Western Carpathians and the Pannonian Basin. The populations of O. dolium display a high genetic diversity with maximum intraspecific p-distances of 18.4% (COI) and 14.4% (16S). The existence of various diverged clades suggests the survival in several geographically separated refuges. Moreover, the sequence patterns provide evidence of multiple migrations between the Alps and the Western Carpathians. The results indicate that the Southern Calcareous Alps were probably colonized only during the Holocene.

Paraphyly and budding speciation in the hairy snail (Pulmonata, Hygromiidae)

Delimitation of species is often complicated by discordance of morphological and genetic data. This may be caused by the existence of cryptic or polymorphic species. The latter case is particularly true for certain snail species showing an exceptionally high intraspecific genetic diversity. The present investigation deals with the Trochulus hispidus complex, which has a complicated taxonomy. Our analyses of the COI sequence revealed that individuals showing a T. hispidus phenotype are distributed in nine highly differentiated mitochondrial clades (showing p-distances up to 19%). The results of a parallel morphometric investigation did not reveal any differentiation between these clades, although the overall variability is quite high. The phylogenetic analyses based on 12S, 16S and COI sequences show that the T. hispidus complex is paraphyletic with respect to several other morphologically well-defined Trochulus species (T. clandestinus, T. villosus, T. villosulus and T. striolatus) which form well-supported monophyletic groups. The nc marker sequence (5.8S-ITS2-28S) shows only a clear separation of T. o. oreinos and T. o. scheerpeltzi, and a weakly supported separation of T. clandestinus, whereas all other species and the clades of the T. hispidus complex appear within one homogeneous group. The paraphyly of the T. hispidus complex reflects its complicated history, which was probably driven by geographic isolation in different glacial refugia and budding speciation. At our present state of knowledge, it cannot be excluded that several cryptic species are embedded within the T. hispidus complex. However, the lack of morphological differentiation of the T. hispidus mitochondrial clades does not provide any hints in this direction. Thus, we currently do not recommend any taxonomic changes. The results of the current investigation exemplify the limitations of barcoding attempts in highly diverse species such as T. hispidus.

Continuing fragmentation of a widespread species by geographical barriers as initial step in a land snail radiation on crete

The phylogeographic structure of the land snail Xerocrassa mesostena on Crete inferred from AFLP markers and mitochondrial cox1 sequences can be explained by three mechanisms: gene flow restriction, population expansion and leptokurtic dispersal. Gene flow restriction by geographic barriers caused subdivision of the gene pool into distinct clusters. Population expansion was probably facilitated by deforestation of Crete in the postglacial. Newly available areas were colonized by leptokurtic dispersal, i.e. slow active expansion resulting in isolation by distance within the clusters and occasional long distance dispersal events that resulted in departures from the isolation by distance model. Less than one percent of the AFLP markers show correlations with environmental variables. Random phylogeographic breaks in the distribution of the mitochondrial haplotype groups indicate that single locus markers, especially mitochondrial DNA, might result in a misleading picture of the phylogeographic structure of a species. Restriction of gene flow between metapopulations caused by geographical barriers can interact with sexual selection resulting in the differentiation of these metapopulations into separate species without noticeable ecological differentiation. Evidence for gene flow between parapatrically distributed evolutionary units representing different stages of the speciation process suggests that the ongoing process of fragmentation of the X. mesostena complex might be an example for parapatric speciation. The lack of ecological differentiation between these units confirms theoretical predictions that divergent selection for local adaptation is not required for rapid speciation.