scholarly journals Adult Shell-size Regulation in Conispirally-coiled Shells: Evidence for a Widespread Negative Covariance between Whorls Growth-rate and the Final Number of Whorls in Land Snails

2021 ◽  
pp. 95-106
Author(s):  
Jean Béguinot
Keyword(s):  
Growth Rate ◽  
Present Report ◽  
Land Snail ◽  
Land Snails ◽  
Snail Species ◽  
Shell Size ◽  
Regulation Process ◽  
Intraspecific Variations ◽  
Taxonomic Range ◽  
Species Specific

As shown, in particular, by the late S.J. Gould, the involvement of a regulation process, aiming at limiting the range of intraspecific variations in adult shell size, in those land snail species with determinate growth, can be indirectly, but conveniently, diagnosed by highlighting a negative covariance between the whorls growth-rate and the whorls number reached at adulthood. However, up to now, such kind of regulation had only been demonstrated in very few cases among land snails and shelled Gastropods in general. Accordingly, quite more extensive checking is required, across both the taxonomic spectrum and the geometrical range of shell profiles. The present report is a very preliminary contribution addressing these issues, which have been neglected for too long. Considering a still limited number of eight species, yet largely encompassing both taxonomic range and shell profiles, it is shown that strong negative covariances between whorls growth-rate and whorls number are systematically highlighted, thereby supporting the involvement of an efficient regulation process of adult shell size and shape in each eight species. Moreover, the degree of regulation of the adult shell size has been quantified and this regulation proves being remarkably effective as a whole, while yet remaining highly species-specific, with very significant disparities among species – and this, somewhat surprisingly, being quite irrespective of the type of geometrical profiles of shells, among the studied species.

scholarly journals Intra-Specific Variability in Whorl Growth-Rate among Land Gastropods with Conispirally-Coiled Shells

2021 ◽  
pp. 59-69
Author(s):  
Jean Béguinot
Keyword(s):  
Growth Rate ◽  
Statistical Significance ◽  
Repeated Measurements ◽  
Species Level ◽  
Shell Shape ◽  
Snail Species ◽  
Strong Positive Correlation ◽  
Shell Size ◽  
Strong Negative Correlation ◽  
Species Specific

For most conispirally-coiled Gastropods with determinate growth, the geometry of spirally-winding whorls is usually constrained by a strong negative correlation between whorl growth rate and the number of whorls reached at adulthood, as originally reported by the late S.J. Gould. Yet, beyond the tight control of shell-shape at the species level – resulting from this constraint – what about the amplitude of the intra-specific variability of whorl growth-rate, partly contributing to the variability of the overall shell-size at the species level? I address the issue by designing and implementing a new, indirect method for routinely evaluating whorl growth-rate, thereby aiming at considerably saving measurement time, and making it possible to easily achieve repeated measurements across samples large enough to reach statistical significance. This approach was applied to a series of eight common land snail species. The amplitude of intra-specific variability in whorl growth, evaluated this way, proves: (i) being markedly different among the eight investigated species (by a factor that can exceed 2x); (ii) being, yet, high enough, in all cases, to require compensating variations in the adult number of whorls, so as to limit the resulting consequences on the amplitude of the intra-specific variability of adult shell-size. Despite those marked differences in the amplitudes of intra-specific variability of whorl growth-rate among species, no significant relationship was observed between intraspecific variability of whorl growth rate and species-specific shell-shape types (discoidal/globular/elongate) and only weak positive relationship was observed with species-specific typical shell sizes. However, a rather strong positive correlation was found, as expected, between the degree of intra-specific variability of the whorl growth-rate and the degree of intra-specific variability of the number of whorls reached at adulthood (with the yet unexplained exception of one among the eight investigated species).

Organ- and species-specific accumulation of metals in two land snail species (Gastropoda, Pulmonata)

2013 ◽  
Vol 449 ◽  
pp. 470-481 ◽  
Author(s):  
Magdalena Boshoff ◽  
Kurt Jordaens ◽  
Thierry Backeljau ◽  
Suzanna Lettens ◽  
Filip Tack ◽  
...  
Keyword(s):  
Land Snail ◽  
Snail Species ◽  
Specific Accumulation ◽  
Accumulation Of Metals ◽  
Species Specific

scholarly journals The direct cost of traumatic secretion transfer in hermaphroditic land snails: individuals stabbed with a love dart decrease lifetime fecundity

2015 ◽  
Vol 282 (1804) ◽  
pp. 20143063 ◽  
Author(s):  
Kazuki Kimura ◽  
Satoshi Chiba
Keyword(s):  
Direct Cost ◽  
Sexual Conflict ◽  
Mating Behaviour ◽  
Land Snail ◽  
Fertilization Success ◽  
Land Snails ◽  
Snail Species ◽  
Arms Races ◽  
Lifetime Fecundity ◽  
Sperm Donors

Several taxa of simultaneously hermaphroditic land snails exhibit a conspicuous mating behaviour, the so-called shooting of love darts. During mating, such land snail species transfer a specific secretion by stabbing a mating partner's body with the love dart. It has been shown that sperm donors benefit from this traumatic secretion transfer, because the secretions manipulate the physiology of a sperm recipient and increase the donors' fertilization success. However, it is unclear whether reception of dart shooting is costly to the recipients. Therefore, the effect of sexual conflict and antagonistic arms races on the evolution of traumatic secretion transfer in land snails is still controversial. To examine this effect, we compared lifetime fecundity and longevity between the individuals that received and did not receive dart shooting from mating partners in Bradybaena pellucida . Our experiments showed that the dart-receiving snails suffered reduction in lifetime fecundity and longevity. These results suggest that the costly mating behaviour, dart shooting, generates conflict between sperm donors and recipients and that sexually antagonistic arms races have contributed to the diversification of the morphological and behavioural traits relevant to dart shooting. Our findings also support theories suggesting a violent escalation of sexual conflict in hermaphroditic animals.

The land snail fauna of a South American rainforest biodiversity hotspot: the Panguana conservation area in the Peruvian Amazon

2019 ◽  
Vol 85 (3) ◽  
pp. 311-318
Author(s):  
Birte Wendebourg ◽  
Bernhard Hausdorf
Keyword(s):  
Distinct Group ◽  
Land Snail ◽  
Global Scale ◽  
Land Snails ◽  
Snail Species ◽  
South American ◽  
Conservation Area ◽  
Additional Species ◽  
Synanthropic Species ◽  
Very High

Abstract We investigated the land snail fauna of the Panguana conservation area on the western rim of the Amazonas basin in Peru. A total of 2,322 individuals assigned to 65 land snail species were collected in 32 plots. Ten additional species were found in collections made on previous expeditions to Panguana. On the basis of available data, Panguana is the most species rich locality for land snails in South America. The species density of 75 land snail species in c. 2 km2 of rather homogeneous rainforest is also high on a global scale. The land snail fauna of Panguana is characterized by a very high proportion of species belonging to the carnivorous family Scolodontidae, many of which are likely to be new to science. The fauna includes seven species that are new records for Peru, and the species Hirtudiscus sp., Xenodiscula venezuelensis, Geostilbia aperta, Guppya gundlachii and Thysanophora plagioptycha represent genera not previously recorded from the country. The synanthropic species Allopeas gracile, Opeas hannense, Subulina octona, Geostilbia aperta and Gastrocopta servilis form an ecologically distinct group that occurs mainly in sites strongly modified by humans. The presence of these species on the margin of the Amazon rainforest is evidence of the ongoing homogenization of the global fauna.

Land snails on Porto Santo: adaptive and non-adaptive radiation

1996 ◽  
Vol 351 (1337) ◽  
pp. 309-327 ◽  
Keyword(s):  
Distribution Patterns ◽  
Land Snail ◽  
Land Snails ◽  
Regional Differentiation ◽  
Similar Species ◽  
Adaptive Responses ◽  
Shell Size ◽  
A Value ◽  
Allopatric Divergence ◽  
Evolution Proceeds

A survey has been made of the land snail fauna of Porto Santo, Madeiran archipelago. Porto Santo is an isolated island about 12 km long by 5 km wide. The fauna is exceptionally species-rich and characterisied by radiations of species in several families, especially the Helicidae. Sixty-five samples from the mainland and five offshore islets yielded 56 species, 84% of them endemic, with a mean of 11.5 species per site, and marked regional differentiation in faunal composition. A given site produces on average only approximately one fifth of the number of species possible, equivalent to a value for Whittaker’s index of diversity of 4.5. Patterns of localization occur on the peaks to the east and west of the island, with numerous cases of replacement by congeneric and morphologically similar species. Local areas have assemblages of species differing in shell size and shape, which probably exploit different niches, the pattern in one area paralleling that in others. The low-lying sandy areas which separate these areas are now unfavourable to many endemic species; those which do occur in them tend to have island-wide distributions. Morphological variation in such species appears to have ecological rather than geographical correlates. We conclude that adaptive responses have occurred, but that much of the species richness can be interpreted as non-adaptive, that is, due to allopatric divergence in isolation by species which retain similar niches. Even on so small a land mass the topography is such that for many land molluscs it represents a cluster of refuges intermittantly connected through impermanent and often unfavourable sandy environments, on each of which evolution proceeds independently. Differences in distribution patterns between families probably arise because they evolved at different times in the island’s history. These results are compared with those from snail faunas in other parts of the world, some of which are similar to them.

Production of Natural Bioceramic from Land Snails

2011 ◽  
Vol 493-494 ◽  
pp. 287-292 ◽  
Author(s):  
D. Kel ◽  
Hasan Gökçe ◽  
D. Bilgiç ◽  
D. Ağaoğulları ◽  
I. Duman ◽  
...  
Keyword(s):  
Helix Pomatia ◽  
Land Snail ◽  
Land Snails ◽  
Snail Species ◽  
Growing Up ◽  
Limited Information ◽  
X Ray Diffraction ◽  
Ultrasonic Equipment ◽  
Liquid Part ◽  
Commercially Important

There are thousands of land snail species, ranging in size from 1 mm to the Giant African Snail growing up to a foot long. Two species, known as escargot, helix aspersa and helix pomatia, are commercially important. Helix pomatia is abundant in Turkey. Those snails are exported usually without shells. Shells are damped to trash sites or used as substitute food for animals. The shell is rich in calcium carbonate and some other minor minerals. Thus, snails’ shells can be used as a source for bioceramic production. So far, in the literature there are lot of papers about converting calcite and aragonite structures to hydroxyapatite (HA), like corals, sea shells, sea urchin and other sea creatures. However, there is very limited information about converting land snail shells to HA and other bioceramic phases. The aim of this work was to produce various phases of bioceramic materials from land snails’ shells which are left as a residue waste after their export procedures. Empty local land snails’ shells (helix pomatia) were collected in Istanbul. They were washed, dried, crushed and ball milled until a powder of 100 µm particles size was obtained. Raw powders were stirred at 80°C for 15 min on a hotplate. A second part of the raw powder was stirred with an ultrasonic stirrer at 80°C for 15 min in an ultrasonic equipment. Equivalent amount of H3PO4 was added drop by drop into the solution. The reaction lasted for 8h. Then, to evaporate the liquid part, the mixtures were put into an incubator at 100°C for 24 h and the resultant dried sediments were collected. The produced powders were analyzed with X-ray diffraction, IR and scanning electron microscope (SEM). The experimental results confirmed the formation of various Ca-phosphates, specifically monetite, fluorapatite and some other minor calcium phosphate phases. Bioceramic production from land snail is a reliable and economic way comparing to other tedious methods of producing synthetic HA and other various bioceramics phases.

scholarly journals Contrasting responses of two xerophilous land snails to fire and natural reforestation

2012 ◽  
Vol 81 (3) ◽  
pp. 167-S1 ◽  
Author(s):  
Xavier Santos ◽  
Vicenç Bros ◽  
Elisabet Ros
Keyword(s):  
Key Management ◽  
Spatial Scales ◽  
Land Snail ◽  
Western Mediterranean ◽  
Land Snails ◽  
Holm Oak ◽  
Aerial Photographs ◽  
Snail Species ◽  
Limited Mobility ◽  
Faunal Distribution

Land-use change is considered the main disturbance in landscape structure and composition, directly affecting faunal distribution and species richness worldwide. Wildfires and natural reforestation alter habitat structure in terms of vegetation cover and also in soil composition and moisture; these processes hence trigger habitat transformations that act as opposing forces at small spatial scales. We have explored the contrasting effects of wildfires and natural reforestation on two land-snail species of the genus Xerocrassa, which are endemic in the western Mediterranean. Snails were sampled in pine and Holm oak forest, stony bare slopes and burnt sites. Both species followed a similar pattern: they were present in more than 75% of the stony bare slope sites and around 50% of the burnt sites, but were almost absent in Holm oak forests. The comparison of aerial photographs from 1956 and 2003 showed that stony bare slopes were significantly larger in 1956, this indicating that the natural reforestation might close these habitats, and consequently threaten the viability of the Xerocrassa populations. Given their limited mobility, the presence of Xerocrassa at burnt sites suggests that these species live in small and cryptic populations within the forest, surviving fire and expanding their distribution due to the appearance of adequate habitats. Our study shows that natural reforestation and fire play opposing roles in conserving Xerocrassa populations. The preservation of stony bare slopes as well as other open areas is a key management guideline to maintain landscape mosaics and help future conservation of species of open habitats such as these vulnerable endemic gastropods.

DIVERSITY AND ECOLOGY OF LAND SNAILS IN GUNUNG HALIMUN SALAK NATIONAL PARK (GHSNP) IN JAVA, INDONESIA

Zoo Indonesia ◽  
2020 ◽  
Vol 28 (1) ◽  
Author(s):  
Ayu Savitri Nurinsiyah ◽  
Ita Faizah ◽  
Yogi Prasetio ◽  
Tedi Setiadi ◽  
Ristiyanti Marsetiowati Marwoto ◽  
...  
Keyword(s):  
Species Richness ◽  
Soil Ph ◽  
National Park ◽  
New Records ◽  
Land Snail ◽  
Montane Forest ◽  
Land Snails ◽  
Tropical Montane Forest ◽  
Snail Species ◽  
June July

The land snail fauna of the largest tropical montane forest in Java, the Gunung Halimun Salak National Park (GHSNP), was surveyed during the dry season (June-July) in 2015, concentrating on four park’s resorts, i.e. Cikaniki, Mt. Botol, Cisarua (Halimun area) and Cidahu (Salak area). In total, 399 specimens representing 43 species were collected. Prior to the surveys, 48 land snail species were known from the GHSNP. Fifteen new records for the GHSNP were discovered so 63 species are now known to inhabit the Park. This number represent 25% of the total land snail fauna of Java. 21 of the species found in GHSNP are endemic to Java. The species richness of the plots in GHSNP was correlated with soil pH and the composition of the land snail communities was correlated with elevation, annual mean temperature, and amount of deadwood.

scholarly journals Plants critical for Hawaiian land snail conservation: arboreal snail plant preferences in Puʻu Kukui Watershed, Maui

Oryx ◽  
2021 ◽  
pp. 1-6
Author(s):  
Wallace M. Meyer ◽  
Lily M. Evans ◽  
Connor J.K. Kalahiki ◽  
John Slapcinsky ◽  
Tricia C. Goulding ◽  
...  
Keyword(s):  
Land Snail ◽  
Land Snails ◽  
Conservation Strategies ◽  
Snail Species ◽  
Native Plant ◽  
Plant Host ◽  
Critical Habitat ◽  
Host Preferences ◽  
Island Endemic ◽  
Understorey Plants

Abstract The Hawaiian archipelago was formerly home to one of the most species-rich land snail faunas (> 752 species), with levels of endemism > 99%. Many native Hawaiian land snail species are now extinct, and the remaining fauna is vulnerable. Unfortunately, lack of information on critical habitat requirements for Hawaiian land snails limits the development of effective conservation strategies. The purpose of this study was to examine the plant host preferences of native arboreal land snails in Puʻu Kukui Watershed, West Maui, Hawaiʻi, and compare these patterns to those from similar studies on the islands of Oʻahu and Hawaiʻi. Concordant with studies on other islands, we found that four species from three diverse families of snails in Puʻu Kukui Watershed had preferences for a few species of understorey plants. These were not the most abundant canopy or mid canopy species, indicating that forests without key understorey plants may not support the few remaining lineages of native snails. Preference for Broussaisia arguta among various island endemic snails across all studies indicates that this species is important for restoration to improve snail habitat. As studies examining host plant preferences are often incongruent with studies examining snail feeding, we suggest that we are in the infancy of defining what constitutes critical habitat for most Hawaiian arboreal snails. However, our results indicate that preserving diverse native plant assemblages, particularly understorey plant species, which facilitate key interactions, is critical to the goal of conserving the remaining threatened snail fauna.

scholarly journals Sequencing of Transcriptome and Small RNA Revealed the Xenobiotic Metabolism-Related Genes and Potential Regulatory miRNA in Asian Tramp Snail

2021 ◽  
Vol 11 ◽  
Author(s):  
Qun Yang ◽  
Wanjun Yang ◽  
Feng Shang ◽  
Biyue Ding ◽  
Jinzhi Niu ◽  
...  
Keyword(s):  
Small Rna ◽  
Average Length ◽  
Xenobiotic Metabolism ◽  
Molecular Study ◽  
Land Snail ◽  
Land Snails ◽  
Cytochrome P450 Monooxygenases ◽  
Snail Species ◽  
P450 Monooxygenases ◽  
Genes Encoding

The Asian tramp snail, Bradybaena similaris (Ferusssac), is an invasive land snail species and has been a rising agricultural pest in south of China. As a pest, it also plays a role in transmission of Angiostrongylus cantonensis. However, present studies on this species are rare and the molecular information is limited. For this purpose, we sequenced the transcriptome and small RNA of B. similaris collected from citrus orchards. In total, 89,747 unigenes with an N50 size of 1287 bp and an average length of 817 bp were generated from ∼8.9 Gb transcriptome and 31 Mb clean reads were generated from ∼36 Mb small RNA library. To demonstrate the usefulness of these two datasets, we analyzed a series of genes associated with xenobiotic metabolism and core RNAi machinery. Analysis of the transcripts resulted in annotation of 126 putative genes encoding cytochrome P450 monooxygenases (CYP, 45), carboxyl/cholinesterases (CCE, 13), glutathione-S-transferases (GST, 24), and ATP-binding cassette transporters (ABC, 44). Analysis of the small RNA detected 42 miRNAs. In addition, four genes involved in small RNA pathways (miRNA, piRNA, and siRNA) were identified, and a total of 430 genes that can be targeted by miRNAs were predicted. Moreover, we found that a few miRNAs could target certain genes involved in xenobiotic metabolism. Therefore, we believe that these two datasets and the characterization of the identified/predicted genes will facilitate the molecular study of this species as well as other land snails with agricultural importance.

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