Group Of Land Snails Research Articles

Review of the Pupilloidea of Pakistan (Gastropoda: Eupulmonata: Cochlicopidae, Chondrinidae, Orculidae, Pyramidulidae)

The land snail fauna of Pakistan is poorly known. During surveys conducted in the summer months of 1990–1992 the Pupilloidea was the most diverse and commonly encountered group of land snails. The Chondrinidae, Cochlicopidae, Orculidae, and Pyramidulidae are reviewed herein. Sphyradium doliolum (Bruguière, 1792) is recorded from Pakistan for the first time. New Pakistan records for Granopupa lapidaria (Hutton, 1849), Cochlicopa cf. lubrica (O. F. Müller, 1774), and Pyramidula humilis (Benson, 1838) are provided. Pyramidula cf. salimalii is reported from localities other than the type locality for the first time. An unidentifiable species of Pyramidula is also reported.

Geology constrains biomineralization expression and functional trait distribution in the Mountainsnails

AbstractAimGeographic variation in metabolic resources necessary for functional trait expression can set limits on species distributions. For species that need to produce and maintain biomineralized traits for survival, spatial variation in mineral macronutrients may constrain species distributions by limiting the expression of biomineralized traits. Here, we examine whether Oreohelix land snails that express heavily biomineralized shell ornaments are restricted to CaCO3 rock regions, if they incorporate greater amounts of CaCO3 rock carbon in their shell than less biomineralized smooth forms, and if ornamentation increases shell strength.LocationWestern United States.TaxonOreohelix land snails.MethodsWe used random forest classification models at multiple spatial resolutions to evaluate the contribution of topographic, vegetation, climate, and geologic variables in predicting the presence of heavily biomineralized shell ornaments across the range of Oreohelix. We then measured and compared shell biometric variables, 14C/12C ratios, and peak force for fracture for ornamented and smooth forms from calcareous and non‐calcareous substrates.ResultsDistance to CaCO3 rock was the most important variable in all models and closer proximity to CaCO3 rock was associated with greater probability of local ornamentation classification. Pairwise comparisons of 14C/12C ratios in closely occurring ornamented vs. smooth population pairs revealed ornamented forms incorporate greater CaCO3 rock carbon than smooth forms. Ornamented types measured in this study were generally heavier and required greater peak force for fracture than smooth forms, except when comparing ornamented forms to smooth forms sampled from CaCO3 rock.Main ConclusionsBiomineralization expression, species distribution, and trait function appear to be constrained by mineral supply in a highly diverse group of land snails. This trait‐environment relationship provides a basis for future investigations of CaCO3 macronutrient constraints on shell form and species distribution in other terrestrial molluscs and has a direct impact on the management of Oreohelix species.

Molecular phylogeny and trait evolution of Madeiran land snails: radiation of the Geomitrini (Stylommatophora: Helicoidea: Geomitridae)

AbstractThe Geomitrini is the most species‐rich group of land snails in the Madeiran Archipelago. The phylogeny of the group is reconstructed based on mitochondrial and nuclear genetic markers. The timing of diversification, the colonisation history of the islands of the Madeiran Archipelago and the evolution of characters of the dart apparatus are studied. The results of the phylogenetic analyses confirm the sister group relationship of Geomitrini and Cochlicellini, but also show that several previously accepted genus‐group taxa are not monophyletic. A new classification for the Geomitrini is proposed, including the description of two new genera, Domunculifex Brozzo, De Mattia, Harl & Neiber, n. gen. and Testudodiscula Brozzo, De Mattia, Harl & Neiber, n. gen. The onset of diversification of Geomitrini was dated in our analysis at 13 Ma, which largely coincides with the emergence of the present‐day islands. The ancestral state estimation recovered the presence of two appendiculae in the reproductive system as the ancestral state in Geomitrini. One appendicula was lost three times independently within the tribe and is even missing completely in one group. The ancestral area estimation suggests recurrent colonisations of Madeira (and the Ilhas Desertas) from the older island Porto Santo.

Integrative taxonomic consideration of the Holarctic Euconulus fulvus group of land snails (Gastropoda, Stylommatophora)

While among the most common Holarctic land snails, species of the Euconulus fulvus group have been subject to considerable recent taxonomic controversy. Based on 76 Euconulus populations collected across Eurasia and North America, we empirically evaluated these competing taxonomic hypotheses through an integration of nDNA and mtDNA phylogenetics, shell morphometrics and various qualitative traits. Our results support the existence of five taxa: Euconulus alderi (Atlantic Europe to western North America), E. fresti sp. nov. (North America), E. fulvus fulvus (Europe), E. fulvus egenus (central Asia to Atlantic North America), and E. polygyratus (north-eastern North America). Each species-level entity possessed a unique suite of observable shell features allowing for accurate identification without need of DNA sequence information. Our data did not support the recent erection of E. callopisticus, E. praticola, and E. trochiformis to species-level status. This work also helps illustrate the importance of using consensus across DNA and shell/soft body features in assessing species-level taxonomy and in determining those features which allow for accurate identification. It furthermore documents the importance of basing taxonomic work on samples drawn from across the entire geographic and ecological range of the study group.http://zoobank.org/urn:lsid:zoobank.org:pub:97985479-EDF8-4B94-A825-AC42BF31F597

Trophic Transfer and Transformation of CeO2 Nanoparticles along a Terrestrial Food Chain: Influence of Exposure Routes.

The trophic transfer and transformation of CeO2 nanoparticles (NPs) through a simulated terrestrial food chain were investigated using a radiotracer technique and X-ray absorption near edge structure (XANES). Radioactive 141CeO2 NPs were applied to head lettuce ( Lactuca sativa), treated via root exposure in its potting soil (5.5 or 11 mg/plant) for 30 days or foliar exposure (7.2 mg/plant, with half of the leaves treated and the other half not) for 7 days. Subsequently, two groups of land snails ( Achatina fulica) were exposed to 141Ce via either a direct (i.e., feeding on the lettuce leaves with 141Ce-contaminated surfaces) or an indirect/trophic (i.e., feeding on the lettuce leaves with systemically distributed 141Ce) route. To evaluate the influence of exposure routes, the Ce contents of the lettuce, snail tissues, and feces were determined by radioactivity measurements. The results show that both assimilation efficiencies (AEs) and food ingestion rates of Ce are greater for the trophic (indirect) exposure. The low AEs indicate that the CeO2 NPs ingested by snails were mostly excreted subsequently, and those that remained in the body were mainly concentrated in the digestive gland. XANES analysis shows that >85% of Ce was reduced to Ce(III) in the digestive gland under direct exposure, whereas Ce in the rest of the food chain (including feces) was largely in its original oxidized (IV) state. This study suggests that CeO2 NPs present in the environment may be taken up by producers and transferred to consumers along food chains and trophic transfer may affect food safety.

Molecular phylogeny and biogeography of the land snail family Hygromiidae (Gastropoda: Helicoidea)

The Hygromiidae is a highly diverse group of land snails with a distribution range stretching throughout the Palearctic region from the Macaronesian Islands to the Russian Far East and reaching southwards to the north-eastern Ethiopian region. So far, the classification of the family largely rested on the structure of the dart apparatus, an accessory genital organ. We used nuclear and mitochondrial DNA sequences of almost all genera to reconstruct the phylogeny of the Hygromiidae. Several of the clades found in the molecular phylogenetic analyses represent regional radiations that partly show a high variation in the structure of the dart apparatus. Thus, several of the currently accepted subdivisions of the family, which included taxa with similar dart apparatus from different regions, turned out to be polyphyletic. We newly delimit three subfamilies within the family, Hygromiinae, Leptaxinae and Trochulinae on the basis of our phylogenetic analyses. The Hygromiinae are further subdivided into Hygromiini and Perforatellini trib. nov. The Leptaxinae are classified in Leptaxini, Metafruticicolini and Cryptosaccini trib. nov. The Trochulinae are the most diverse group including Ciliellini, Archaicini, Ganulini trib. nov., Urticicolini trib. nov., Trochulini, Caucasigenini trib. nov., Ashfordini trib. nov., Halolimnohelcini and Monachaini. Moreover, two new genera, Coronarchaica gen. nov. from Central Asia and Noricella gen. nov. from the Alps, are described. The Hygromiidae originated in the western Palaearctic, from where the Central Asian mountain regions, the Macaronesian Islands, the Caucasus region and sub-Saharan East Africa were colonized. The radiation of the Hygromiidae as well as those of several other land snail families was dispersal limited. Because of the low dispersal abilities of land snails, the period until an isolated region is colonized by a group by chance dispersal is comparatively longer than the period necessary for morphological and ecological diversification of the group within the newly colonized region. Some of the regional radiations coincided with orogeny in the respective areas and were probably triggered by the development of geographical barriers and new niches.

Two complete mitochondrial genomes from Praticolella mexicana Perez, 2011 (Polygyridae) and gene order evolution in Helicoidea (Mollusca, Gastropoda).

Helicoidea is a diverse group of land snails with a global distribution. While much is known regarding the relationships of helicoid taxa, comparatively little is known about the evolution of the mitochondrial genome in the superfamily. We sequenced two complete mitochondrial genomes from Praticolella mexicana Perez, 2011 representing the first such data from the helicoid family Polygyridae, and used them in an evolutionary analysis of mitogenomic gene order. We found the mitochondrial genome of Praticolella mexicana to be 14,008 bp in size, possessing the typical 37 metazoan genes. Multiple alternate stop codons are used, as are incomplete stop codons. Mitogenome size and nucleotide content is consistent with other helicoid species. Our analysis of gene order suggested that Helicoidea has undergone four mitochondrial rearrangements in the past. Two rearrangements were limited to tRNA genes only, and two involved protein coding genes.

English

Limicolaria aurora belongs to the group of land snails commonly called garden snails. This study seeks to use shell morphology and random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) to examine gross morphological differences in populations of L. aurora from New Bussa (guinea savannah) and Benin City (tropical rain forest) in Nigeria and possibly delimit the populations into sub species. A total of one hundred and ten specimens of L. aurora made up of fifty five individuals from each of the two ecological zones were collected randomly for the study. Data on shell parameters including: height of shell (SH), width of shell (SW), aperture height (AH), aperture width (AW), spire length (SL), and first whorl length (1WL) measured on each snail were subjected to one way analysis of variance (ANOVA). Principal component analysis (PCA) and canonical variates analysis (CVA) were performed on the data using PAST statistical software. DNA which was extracted from the muscular tissues of the foot of eight individuals from each location using cetyltrimethylammonium bromide (CTAB) method was subjected to RAPD-PCR. Amplification of the DNA was done using five primers (OPB-12, OPB-18, OPH-08, OPD-11 and OPS-13). Analyses showed significant differences (P<0.05) in L. aurora populations within and between the vegetation zones revealing great heterogeneity in the populations. Both PCA and CVA clusters did not separate the populations into distinct sub-populations. SH was the most variable morphological characteristic and consequently the most suitable for the separation of L. aurora specimens into distinct populations. All the primers used in the amplification of the DNA produced polymorphic bands. The Unweighted Pair Group Method with Arithmetic Mean (UPGMA) cluster diagram revealed two major clades within the snail populations with about 74% similarity. The study showed that RAPD-PCR analysis is more suitable for delimiting populations of L. aurora than morphometrics and that the basis for gross morphological differences in these populations might not only be environmental but also genetic factors. Key words: Achatinidae, biodiversity, environmental factors, morphometrics, phylogenetics, shell, sub-populations, variation.

Evolutionary and biogeographical history of the land snail family Urocoptidae (Gastropoda: Pulmonata) across the Caribbean region

AbstractAimLand snails, because of their low vagility, are ideal organisms for probing biogeographical hypotheses. This study is the first to examine the evolutionary and biogeographical history of a group of land snails from the Caribbean region using molecular phylogenetics. It focuses on the family Urocoptidae that displays extraordinary diversity, particularly in the Greater Antilles.LocationCaribbean region.MethodsWe reconstructed the phylogeny of Urocoptidae based on multi‐locus (partial 28S, H3 andCOIsequences) analyses (MrBayes,BEAST,GARLI) of 65 species, representing 44 recognized genera. Biogeographical analyses of a subset of the time‐calibratedBEASTtrees were made both with (DECandDEC+J analysis inBioGeoBEARS) and without (S‐DIVAinRASP) palaeogeographical assumptions. In theDECandDEC+J analyses we examined the effect of different settings for dispersal between directly connected areas relative to that between areas without direct land connection.ResultsUrocoptidae has been present on the Greater Antilles Arc from at least Middle Eocene onwards. Morphologically diverse and previously unrecognized clades evolved on most Caribbean (palaeo)islands. Jamaica was colonized at least twice. Dispersal multiplier matrices with moderately constrained dispersal between areas without direct land connections describe the phylogeographical history of the family with higherDECandDEC+J lnL scores than uniform matrices.Main conclusionsUrocoptids constitute an old element of the Greater Antillean biota, predating a proposedGAARlandia landspan connection to South America. The biogeographical history and evolution of Urocoptidae were shaped primarily by the geographical distribution of Caribbean landmasses, in combination with occasional oversea dispersal. Oversea dispersal allowed colonization of palaeogeographically isolated areas, such as Jamaica and present‐day western Cuba, where presumably the absence of ecological competitors led to independent radiations into similar shell types.

BIOGEOGRAPHICAL ANALYSIS OF LAND SNAILS OF CLAUSILIIDAE GRAY FAMILY, 1855 CAUCASUS

Aim. Use in scientific research of biogeographic maps for assessment of biological diversity of individual groups and territories today is a very important technique that is widely used by many researchers. The object of this study was elected phyletic compact group of land snails, characterized by stringent strictly confined to a particular environment and a poor ability to overcome geographical barriers, which makes it very convenient model when conducting ecological and zoogeographical studies. Methods. In work was used the method of blending the modern habitats of the terrestrial mollusk fauna on paleokarst Caucasian Islands Paleogene-Oligocene period. The family Clausiliidae Gray, 1855 was chosen for analysis , as occupying a leading position in species composition relative to other families of mollusks in the Caucasus. Results. The analysis of the propagation of biological diversity of land snails Caucasian family Clausiliidae using the method of «overlay areas», showed a high percentage of the study group attachment to the Caucasus paleo islands - 79% or 50 species from 20 genius are placed within them, while 8 species from 6 genius paleo island found near the borders, and 5 species belonging to 4 genius, marked a considerable distance. Main conclusions. The results demonstrate the ability to use the group of land snails as a model for the study of correlations and paleogeographic reconstruction of the events of the Caucasus Isthmus

Leiostyla beatae n. sp. from eastern Georgia (Gastropoda: Lauriidae).

Leiostyla R.T. Lowe, 1852 is a disjunctly distributed pupilloid group of land snails known from the Macaronesian islands, Western Europe, Algeria, Bulgaria, Turkey, the Caucasus region and Iran (Pilsbry 1922-1923; Schileyko 1984; Gittenberger & Pieper 1988; Hausdorf 1990). In the Neogene the genus was more widespread in Central and Western Europe (Pilsbry 1922). Thus, the Caucasus region and the Macaronesian islands, where the highest recent diversity of Leiostyla species is found (Pilsbry 1922-1923), can be considered refugial areas.

Ecological speciation in an island snail: evidence for the parallel evolution of a novel ecotype and maintenance by ecologically dependent postzygotic isolation

Speciation is the process by which reproductive isolation evolves between populations. Two general models of speciation have been proposed: ecological speciation, where reproductive barriers evolve due to ecologically based divergent selection, and mutation-order speciation, where populations fix different mutations as they adapt to similar selection pressures. I evaluate these alternative models and determine the progress of speciation in a diverse group of land snails, genus Rhagada, inhabiting Rosemary Island. A recently derived keeled-flat morphotype occupies two isolated rocky hills, while globose-shelled snails inhabit the surrounding plains. The study of one hill reveals that they are separated by a narrow hybrid zone. As predicted by ecological speciation theory, there are local and landscape level associations between shell shape and habitat, and the morphological transition coincides with a narrow ecotone between the two distinct environments. Microsatellite DNA revealed a cline of hybrid index scores much wider than the morphological cline, further supporting the ecological maintenance of the morphotypes. The hybrid zone does not run through an area of low population density, as is expected for mutation-order hybrid zones, and there is a unimodal distribution of phenotypes at the centre, suggesting that there is little or no prezygotic isolation. Instead, these data suggest that the ecotypes are maintained by ecologically dependent postzygotic isolation (i.e. ecological selection against hybrids). Mitochondrial and Microsatellite DNA indicate that the keeled-flat form evolved recently, and without major historical disruptions to gene flow. The data also suggest that the two keeled-flat populations, inhabiting similar rocky hills, have evolved in parallel. These snails provide a complex example of ecological speciation in its early stages.

Determinants of species richness and similarity of species composition of land snail communities on Kimberley islands

We investigated patterns in species richness and similarity in species composition of land snail communities in relation to biogeographic and environmental gradients on continental islands along the Kimberley coastline of Western Australia. The camaenid land snails demonstrated high overall species richness, restricted geographical ranges (mostly to a single island) and almost complete turnover of species among islands. In comparison, the overall number of the smaller non-camaenid land snail species was much lower. They also had much wider distributions and a lower level of species turnover among islands. These results are consistent with the differing dispersal abilities of the two groups, one fostering in situ speciation and the other inter-island colonisation. We also show that dispersal ability was not the only driver of species richness and composition of land snail species on islands, but that rainfall, island area and availability of habitat also played a role. Rainfall was the major environmental driver of richness and composition for both groups of land snails. Rainfall was also highly correlated with extent of rainforest cover, habitat that provides a suitable micro-climate for snails and additional ecological niches compared to more open habitats.

Phylogeography and morphological variability in land snails: the Sicilian Marmorana (Pulmonata, Helicidae)

Land snails have long been recognized as suitable organisms for studying phenotypic differentiation and phylogeny in relation to geographical distribution. Morphological data (shell and anatomy biometry on different geographical scales) and partial sequences from mitochondrial genes (cytochrome oxidase subunit I, 16S rDNA) were used to test whether morphological patterns match phylogeny in a diversified group of Sicilian rock-dwelling land snails belonging to the genus Marmorana. The taxonomic implications of the three character sets (shell and anatomical biometry and molecular data) were also considered. The inferred phylogenetic relationships do not match morphological (shell and genitalia) patterns. This result may significantly modify the current taxonomy. Mitochondrial based reconstructions define several supported clades well correlated with geographic distribution and populations were found to be distributed parapatrically. The progressive decline in mitochondrial DNA sequence similarity over a distance of 250 km is consistent with a model of isolation by distance, a pattern previously recognized for other groups of land snails. For one clade of Marmorana, colonization along Mediterranean trade routes appears to be a possibility. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 94, 809–823.

Bronze Age shipwreck snails from Turkey: first direct evidence for oversea carriage of land snails in antiquity

Thirty-six shells of terrestrial gastropods were discovered in underwater archaeological excavations of a Late Bronze Age (3,300 years BP) shipwreck at Uluburun, southern Turkey. Four shells were not related to the wreck and belonged to local species from the nearby coast. The other 32 specimens were accidentally transported with the merchant ship, which had sunk when sailing in a counterclockwise route from the Syro-Palestinian coast via Cyprus to the Aegean and then to Egypt. The Near Eastern endemic Xerocrassa langloisiana and the common eastern Mediterranean synanthrope Xeropicta krynickii were found in amphoras originally containing terebinth resin, destined for Egypt. The combined ranges of the two species and the morphological record point to a narrow area near the Dead Sea, more than 50 km distant from the Mediterranean coast, as the harvesting locality of the resin. A second group of land snails, partly determined as Xp. krynickii, must have been on board the vessel under different circumstances, attached to spiny bushes used to cushion the heavy freight and to prevent the planks from being damaged. The finds provide direct evidence that land snails have been carried on ships for more than 3,000 years, and underline assumptions that human-based oversea dispersal of anthropochorous species in the Mediterranean has occurred since antiquity. The results also show how much can be done if we possess a detailed faunistic knowledge of species distributions and shell morphology.

Opposite shell‐coiling morphs of the tropical land snail Amphidromus martensi show no spatial‐scale effects

Much can be learned about evolution from the identification of those factors maintaining polymorphisms in natural populations. One polymorphism that is only partially understood occurs in land snail species where individuals may coil clockwise or anti‐clockwise. Theory shows that polymorphism in coiling direction should not persist yet species in several unrelated groups of land snails occur in stably polymorphic populations. A solution to this paradox may advance our understanding of evolution in general. Here, we examine two possible explanations: firstly, negative frequency‐dependent selection due to predation; secondly, random fixation of alternative coiling morphs in tree‐sized demes, giving the impression of wider polymorphism. We test these hypotheses by investigating morph‐clustering of empty shells at two spatial scales in Amphidromus martensi populations in northern Borneo: the spatial structure of snail populations is relatively easy to estimate and this information may support one or other of the hypotheses under test. For the smaller scale we make novel use of a statistic previously used in botanical studies (the K‐function statistic), which allows clustering of more than one morph to be simultaneously investigated at a range of scales and which we have corrected for anisotropy. We believe this method could be of more general use to ecologists. The results show that consistent clustering or separation of morphs cannot be clearly detected at any spatial scale and that predation is not frequency‐dependent. Alternative explanations that do not require strong spatial structuring of the population may be needed, for instance ones involving a mechanism of selection actively maintaining the polymorphism.

Effects of Karst Forest Degradation on Pulmonate and Prosobranch Land Snail Communities in Sabah, Malaysian Borneo

Abstract: Limestone (karst) outcrops in Southeast Asia are rich in land snails. Certain groups of land snails, in particular Prosobranchia species, are restricted to limestone and show a high degree of short‐range endemism. Karst habitats are, however, seriously degraded by quarrying, logging, agriculture, and burning. The effect of these disturbances on land snail fauna is unknown, so we studied paired primary and secondary forest localities on six separate limestone hills in Sabah, Malaysian Borneo. Land snails were sampled with a standard protocol and identified to species level. More than 16,000 individuals, belonging to 74 species, were recorded. In most sites, snail diversities did not differ between disturbed and undisturbed plots. However, pulmonate snails were significantly more abundant at disturbed localities than prosobranch snails, whereas abundances for both groups were similar at undisturbed sites. Because Prosobranchia contain many site‐endemic species, our findings suggest that continued exposure to these disturbances will eventually lead to extinctions in this group.

Sexual selection on land snail shell ornamentation: a hypothesis that may explain shell diversity

BackgroundMany groups of land snails show great interspecific diversity in shell ornamentation, which may include spines on the shell and flanges on the aperture. Such structures have been explained as camouflage or defence, but the possibility that they might be under sexual selection has not previously been explored.Presentation of the hypothesisThe hypothesis that is presented consists of two parts. First, that shell ornamentation is the result of sexual selection. Second, that such sexual selection has caused the divergence in shell shape in different species.Testing the hypothesisThe first part of the hypothesis may be tested by searching for sexual dimorphism in shell ornamentation in gonochoristic snails, by searching for increased variance in shell ornamentation relative to other shell traits, and by mate choice experiments using individuals with experimentally enhanced ornamentation. The second part of the hypothesis may be tested by comparing sister groups and correlating shell diversity with degree of polygamy.Implications of the hypothesisIf the hypothesis were true, it would provide an explanation for the many cases of allopatric evolutionary radiation in snails, where shell diversity cannot be related to any niche differentiation or environmental differences.