Divergent Shell Shape as an Antipredator Adaptation in Tropical Land Snails

2008 ◽  
Vol 172 (5) ◽  
pp. 726-732 ◽  
Author(s):  
Masaki Hoso ◽  
Michio Hori
Keyword(s):  
Land Snails ◽  
Shell Shape

scholarly journals From morphology to molecules: a combined source approach to untangle the taxonomy ofClessinia(Gastropoda, Odontostomidae), endemic land snails from the Dry Chaco ecoregion

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5986 ◽  
Author(s):  
Maria Gabriela Cuezzo ◽  
Maria Jose Miranda ◽  
Roberto Eugenio Vogler ◽  
Ariel Anibal Beltramino
Keyword(s):  
Species Identification ◽  
Dna Sequences ◽  
Phylogenetic Analyses ◽  
Molecular Study ◽  
Genetic Distances ◽  
Land Snails ◽  
The Body ◽  
Shell Shape ◽  
Geometric Morphometric ◽  
Morphometric Analyses

BackgroundLand gastropods of the Dry Chaco merit special attention because they comprise a highly diverse but barely studied group.ClessiniaDoering, 1875 are typical inhabitants of this ecoregion. The inclusion of their distribution areas intoSpixiarange, their shell shape similarities, and a former molecular study raised doubts on the monophyly of this genus. The present study review the species ofClessinia, under a morphological, geometric morphometrics, and molecular combined approach.MethodsAdults were collected, photographed, measured, and dissected for anatomical studies. Shell ultrastructure was studied with scanning electron microscope. Geometric morphometric analyses on shells were performed testing if they gave complementary information to anatomy. Two mitochondrial genes, and a nuclear region were studied. Phylogenetic reconstructions to explore the relationships of DNA sequences here obtained to those ofClessiniaandSpixiaspecies from GenBank were performed.ResultsSpecies description on shell, periostracal ornamentation and anatomy is provided. We raised formerClessinia cordovana striatato species rank, naming it asClessinia tulumbensissp. nov. The periostracum, consisting of hairs and lamellae, has taxonomic importance for species identification. Shell morphometric analyses, inner sculpture of penis and proportion of the epiphallus and penis, were useful tools to species identification. Nuclear markers do not exhibit enough genetic variation to determine species relationships. Based on the mitochondrial markers, genetic distances amongClessiniaspecies were greater than 10%, and whileC. cordovana,C. nattkemperi, andC. pagodawere recognized as distinct evolutionary genetic species, the distinction betweenC. stelzneriandC. tulumbensissp. nov. was not evident.ClessiniaandSpixiawere paraphyletic in the molecular phylogenetic analyses. Species ofClessiniahere treated have narrow distributional areas and are endemic to the Chaco Serrano subecoregion, restricted to small patches within the Dry Chaco.ClessiniaandSpixiaare synonymous, and the valid name of the taxon should beClessiniaDoering, 1875 which has priority overSpixiaPilsbry & Vanatta, 1894.DiscussionOur results support the composition ofC. cordovanacomplex by three species,C. cordovana,C. stelzneri, andC. tulumbensissp. nov. The low genetic divergence betweenC. stelzneriandC. tulumbensissp. nov. suggests that they have evolved relatively recently. The formerSpixiaandClessiniaare externally distinguished becauseClessiniahas a detached aperture from the body whorl forming a cornet, periostracal microsculpture extended over dorsal portion of the peristome, five inner teeth on the shell aperture instead of three–four found inSpixia. Morphological similarities exists between both genera in shell shape, type of periostracum microsculpture, reproductive anatomy, besides the overlap in geographic ranges.

Molecular Phylogeny, Evolution of Shell Shape, and DNA Barcoding in Polygyridae (Gastropoda: Pulmonata), an Endemic North American Clade of Land Snails

2014 ◽  
Vol 32 (1) ◽  
pp. 1-31 ◽  
Author(s):  
Kathryn E. Perez ◽  
Nicholas Defreitas ◽  
John Slapcinsky ◽  
Russell L. Minton ◽  
Frank E. Anderson ◽  
...  
Keyword(s):  
Molecular Phylogeny ◽  
Dna Barcoding ◽  
North American ◽  
Land Snails ◽  
Shell Shape ◽  
American Clade

A new subspecies of Ruthenica filograna(Pulmonata: Clausiliidae) from Croatia

2022 ◽  
Vol 32 (1) ◽  
pp. 49-52
Author(s):  
R. Egorov
Keyword(s):  
Land Snails ◽  
Shell Shape ◽  
New Subspecies

A new subspecies of land snails of the clausiliid genus Ruthenica has been found on the territory of Republic of Croatia. Illustrated description is presented. New subspecies differs from others in shell shape, semi-apostrophic aperture and sculpture pattern.

Tracking parallel adaptation of shell morphology through geological times in the land snail genus Pupilla (Gastropoda: Stylommatophora: Pupillidae)

2020 ◽  
Author(s):  
Martin Haase ◽  
Stefan Meng ◽  
Michal Horsák
Keyword(s):  
Morphological Changes ◽  
Land Snail ◽  
Land Snails ◽  
Shell Morphology ◽  
Shell Shape ◽  
Ecological Niches ◽  
Habitat Requirements ◽  
Stochastic Nature ◽  
Niche Shifts ◽  
Molecular Phylogenetic

Abstract Changing environmental conditions force species either to disperse or to adapt locally either genetically or via phenotypic plasticity. Although limits of plasticity can be experimentally tested, the predictability of genetic adaptation is restricted due to its stochastic nature. Nevertheless, our understanding of evolutionary adaptation has been improving in particular through studies of parallel adaptation. Based on molecular phylogenetic inferences and morphological investigations of both recent and fossil shells we tracked the morphological changes in three land snails, Pupilla alpicola, Pupilla loessica and Pupilla muscorum. These species differ in habitat requirements as well as historical and extant distributions with P. alpicola and P. loessica being more similar to each other than to P. muscorum. Therefore, we hypothesized, that the three species reacted independently and individually to the conditions changing throughout the Pleistocene, but expected that changes within P. alpicola and P. loessica would be more similar compared to P. muscorum. Indeed, intraspecific shell shape differences across time were similar in P. alpicola and P. loessica, suggesting that similar niche shifts have led to similar transformations in parallel. In contrast, extant P. muscorum populations were practically identical in shape to their ancestors. They have probably tracked their ecological niches through time.

scholarly journals Interplay of size and shape in miniaturized land snails

2018 ◽  
Author(s):  
Aydin Örstan
Keyword(s):  
Egg Size ◽  
Shell Height ◽  
Land Snails ◽  
Shell Shape ◽  
Functional Constraints ◽  
Surface Areas ◽  
Uniform Distributions ◽  
The Mean ◽  
Potential Factors ◽  
Body Whorl

ABSTRACTThe distribution of the mean greater shell dimensions of 2446 genera of stylommatophoran land snails consists of two groups peaking at 3 mm and 15.3 mm. The 3-mm group includes the miniature snails whose adult shell dimensions range from almost 0.8 mm to less than 1.5 mm. Relative surface area, shell thickness and egg size are discussed as potential factors that may limit the minimum shell dimensions. To obtain uniform distributions, the shell shape is expressed as the expanse angle, defined as the apex angle of a right triangle the height and the base of which are the shell height and diameter, respectively. In terms of expanse angles there are three shell shapes: tall (< 40°), flat (> 50°) and roughly equiaxial (40°-50°). The variation of shell shape with size was analyzed within the morphospace they form. At shell dimensions above 10 mm the lowest expanse angle is about 10°. Below 10 mm, the lower limit of the expanse angle increases as shells get smaller. As a result, no miniature species has a tall shell. It is proposed that two evolutionary functional constraints render small and narrow shells of miniaturized snails nonadaptive. These are the requirements to reduce surface areas to decrease water loss and to have enough volume and a wide enough body whorl to accommodate at least one egg.

Marine and terrestrial molluscs in the sanctuary. The molluscan remains from the 2003–2004 excavations in the Sanctuary of Poseidon at Kalaureia

2019 ◽  
pp. 241-254 ◽  
Author(s):  
George E. Syrides
Keyword(s):  
Land Snails

This paper presents the hand-collected molluscan remains that were recovered from the excavations in Areas C and D of the Sanctuary of Poseidon at Kalaureia, Poros, in the years 2003–2004. The paper aims at the presentation of the finds and at using the molluscan biological and ethological traits to provide insights into the possible capture methods and use. Land snails are also summarily presented.

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