scholarly journals Disentangling the effects of intraspecies variability, phylogeny, space, and climate on the evolution of shell morphology in endemic Greek land snails of the genusCodringtonia

2013 ◽  
Vol 110 (4) ◽  
pp. 796-813 ◽  
Author(s):  
Panayiota Kotsakiozi ◽  
François Rigal ◽  
Efstratios D. Valakos ◽  
Aristeidis Parmakelis
Keyword(s):  
Land Snails ◽  
Shell Morphology ◽  
Intraspecies Variability

scholarly journals Descriptions of four new dextral land snails of the genus Camaena (Gastropoda, Eupulmonata, Camaenidae) from south China

ZooKeys ◽  
2020 ◽  
Vol 996 ◽  
pp. 37-58
Author(s):  
Pei Wang ◽  
Mei-Ling Hu ◽  
Jun-Hong Lin ◽  
Hai-Fang Yang ◽  
Xiao-Jing Li ◽  
...  
Keyword(s):  
New Species ◽  
South China ◽  
Dna Sequences ◽  
Reproductive System ◽  
Phylogenetic Analyses ◽  
Morphological Characteristics ◽  
Land Snails ◽  
Shell Morphology ◽  
Molecular Phylogenetic ◽  
Living Environments

In this study, four new dextral camaenid from China are reported, based on shell morphology, reproductive system anatomy, and molecular phylogenetic analyses: Camaena funingensis Zhou, Wang & Lin, sp. nov., Camaena gaolongensis Zhou, Wang & Lin, sp. nov., Camaena maguanensis Zhou, Wang & Hu, sp. nov., and Camaena yulinensis Zhou, Wang & Hu, sp. nov. Detailed descriptions of the morphological characteristics including shells and genitalia, DNA sequences, and living environments of the four new species are provided, with further comparisons with congeners.

Repeated evolution of an undescribed morphotype of Rhagada (Gastropoda : Camaenidae) from the inland Pilbara, Western Australia

2021 ◽  
Author(s):  
Zoë R. Hamilton
Keyword(s):  
Western Australia ◽  
Land Snails ◽  
Shell Morphology ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Broad Distribution ◽  
Mitochondrial Coi ◽  
Coastal Species ◽  
Repeated Evolution ◽  
Harsh Conditions

An undescribed small, banded morphotype of Rhagada land snails occurs widely in the rocky inland Pilbara region, Western Australia. Phylogenetic analysis of mitochondrial COI and 16S rRNA genes revealed that this novel morphotype is polyphyletic, comprising four distinct major clades, with divergences up to 21.4% at COI. These clades are apparently morphologically cryptic, with no obvious shell differences. Two of these species are associated with the major clade of Rhagada in the Pilbara mainland, one of which appears to be a variant of the larger, more globose species R. pilbarana, which occurs within 20km proximity. The other two small, banded species are phylogenetically distinct from each other and all other known Rhagada. This small, banded morphotype shows evidence for both plesiomorphy and homoplasy. The morphotype has evolved independently at least twice, and is associated with the reasonably uniform habitat and harsh conditions in the elevated hinterland of the inland Pilbara. The broad distribution of the inland, small, banded morphotype conforms to the pattern of broad-scale uniformity of shells of the more coastal species of Rhagada. Its repeated evolution, however, confirms that the morphological uniformity is not simply because of common ancestry, supporting the theory that shell form in Rhagada is adapted to a broadly homogenous environment. Shell morphology in this genus has been demonstrated on more than one occasion to have the potential to adapt to different available environments, and hence shells should be used with a degree of caution for taxonomic interpretation.

scholarly journals Association between shell morphology of micro-land snails (genus Plectostoma) and their predator’s predatory behaviour

2013 ◽  
Author(s):  
Thor-Seng Liew ◽  
Menno Schilthuizen
Keyword(s):  
Land Snails ◽  
Shell Morphology ◽  
Ecological Interactions ◽  
Predatory Behaviour ◽  
Predator Prey ◽  
Resting Behaviour ◽  
Biological Form ◽  
Predation Costs ◽  
Selection Of ◽  
Thickness Shell

Predator-prey interactions are among the main ecological interactions that shape the diversity of biological form. In many cases, the evolution of the mollusc shell form is presumably driven by predation. However, the adaptive significance of several uncommon, yet striking, shell traits of land snails are still poorly known. These include the distorted coiled “tuba” and the protruded radial ribs that can be found in micro-landsnails of the genus Plectostoma. Here, we experimentally tested whether these shell traits may act as defensive adaptations against predators. First, we identified the predators, namely, Atopos slugs and Pteroptyx beetle larvae, and their predatory strategies towards Plectostoma snails. Then, we characterised and quantified the possible anti-predation behaviour and shell traits of Plectostoma snails both in terms of their properties and efficiencies in defending against the Atopos slug predatory strategies, namely, shell-apertural entry and shell-drilling. The results showed that Atopos slugs would first attack the snail by shell-apertural entry, and, should this fail, shift to the energetically more costly shell-drilling strategy. We found that the shell tuba of Plectostoma snails is an effective defensive trait against shell-apertural entry attack. None of the snail traits, such as resting behaviour, shell thickness, shell tuba shape, shell rib density and intensity can protect the snail from the slug’s shell-drilling attack. However, these traits could increase the predation costs to the slug. Further analysis on the shell traits revealed that the lack of effectiveness these anti-predation shell traits may be caused by a functional trade-off between shell traits under selection of two different predatory strategies. Lastly, we discuss our results in the framework of Red Queen predator-prey coevolution and escalation, and propose several key elements for future study.

scholarly journals Cryptic diversity, molecular phylogeny and biogeography of the rock- and leaf litter-dwelling land snails of Belau (Republic of Palau, Oceania)

2008 ◽  
Vol 363 (1508) ◽  
pp. 3401-3412 ◽  
Author(s):  
Rebecca J Rundell
Keyword(s):  
Leaf Litter ◽  
Phylogenetic Reconstruction ◽  
Habitat Type ◽  
Land Snails ◽  
Shell Morphology ◽  
Coi Gene ◽  
28S Rrna ◽  
Republic Of Palau ◽  
Shell Sculpture

The endemic diplommatinid land snails (Caenogastropoda: Mollusca) of Belau (Republic of Palau, Micronesia) are an exceptionally diverse group of largely undescribed species distributed among rock and leaf litter habitats on most of Belau's 586 islands. Diplommatinid shell morphology (e.g. shell sculpture) reflects habitat type. In this study, I analysed a subset of the 90 diplommatinid species representing a broad geographical spread of islands in order to reveal the species' phylogenetic relationships and biogeography within the Belau archipelago. Diplommatinid species from the islands of Yap, Pohnpei, Kosrae and Guam are also included in the analysis. One nuclear (28S rRNA) and two mitochondrial (16S rRNA, COI) gene regions comprising 1906 bp were used for phylogenetic reconstruction. Results show that (i) the Belau Diplommatinidae are not monophyletic, as Guam and Yap species should be included as part of the radiation, (ii) Pohnpei and Kosrae species are highly divergent from Belau diplommatinids, (iii) there is little evidence for in situ radiation within individual Belau islands, (iv) spined and heavily calcified rock-dwelling species form a well-supported clade, and (v) Belau diplommatinid genera are in need of revision.

Evolution of shell apertural barriers in viviparous land snails (Gastropoda: Pulmonata: Clausiliidae)

2014 ◽  
Vol 92 (3) ◽  
pp. 205-213 ◽  
Author(s):  
A. Sulikowska-Drozd ◽  
M. Walczak ◽  
M. Binkowski
Keyword(s):  
Reproductive Strategies ◽  
Three Dimensional ◽  
Land Snails ◽  
Shell Morphology ◽  
Shell Size ◽  
X Ray ◽  
Egg Retention ◽  
Embryonic Shell ◽  
Selective Forces ◽  
Size At Birth

Apertural barriers in the snail shell were frequently associated with adaptation against predators or with reducing water loss. Yet formation of teeth occluding the aperture is costly and potentially precludes life-bearing reproduction. In viviparous species, a trade-off between the shell aperture size and the embryo shell size at birth is expected. This hypothesis was tested in clausiliids, land snails with strong apertural barriers, that displayed a range of reproductive strategies (oviparity, egg retention, viviparity). We assessed their three-dimensional internal shell morphology by means of X-ray microcomputed tomography (XMT). The data were later analysed with a specially designed algorithm that mimics the movement of the spherical embryonic shell in the lumen of the parental shell. It appeared that viviparous reproduction required the widening of the passage through the ultimate whorl, but that did not necessarily lead to a reduction of apertural barriers. This provides an example of evolutionary compromise between enhanced fitness of the offspring owing to a long gestation period and survival of the parent. Clausiliids might be selected for viviparity only if other selective forces were released, e.g., in areas where desiccation was not a major threat. This hypothesis is in congruence with the distribution of viviparous clausiliids in Europe.

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