Geographical variation in shell morphology of juvenile snails (Concholepas concholepas) along the physical–chemical gradient of the Chilean coast

2013 ◽  
Vol 93 (8) ◽  
pp. 2167-2176 ◽  
Author(s):  
Laura Ramajo ◽  
Ángel Baltanás ◽  
Rodrigo Torres ◽  
Patricio H. Manríquez ◽  
Alejandro Rodriguez-Navarro ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Environmental Gradients ◽  
Function Analysis ◽  
Shell Morphology ◽  
Shell Shape ◽  
Phenotypic Traits ◽  
Shell Weight ◽  
Chilean Coast ◽  
Physical Chemical ◽  
Concholepas Concholepas

Changes in phenotypic traits, such as mollusc shells, are indicative of variations in selective pressure along environmental gradients. Recently, increased sea surface temperature (SST) and ocean acidification (OA) due to increased levels of carbon dioxide in the seawater have been described as selective agents that may affect the biological processes underlying shell formation in calcifying marine organisms. The benthic snailConcholepas concholepas(Muricidae) is widely distributed along the Chilean coast, and so is naturally exposed to a strong physical–chemical latitudinal gradient. In this study, based on elliptical Fourier analysis, we assess changes in shell morphology (outlines analysis) in juvenileC. concholepascollected at northern (23°S), central (33°S) and southern (39°S) locations off the Chilean coast. Shell morphology of individuals collected in northern and central regions correspond to extreme morphotypes, which is in agreement with both the observed regional differences in the shell apex outlines, the high reclassification success of individuals (discriminant function analysis) collected in these regions, and the scaling relationship in shell weight variability among regions. However, these extreme morphotypes showed similar patterns of mineralization of calcium carbonate forms (calcite and aragonite). Geographical variability in shell shape ofC. concholepasdescribed by discriminant functions was partially explained by environmental variables (pCO2, SST). This suggests the influence of corrosive waters, such as upwelling and freshwaters penetrating into the coastal ocean, upon spatial variation in shell morphology. Changes in the proportion of calcium carbonate forms precipitated byC. concholepasacross their shells and its susceptibility to corrosive coastal waters are discussed.

scholarly journals Spatial distribution and morphometry of the succineid snail Succinea baconi (Pfeiffer, 1854) in India

2021 ◽  
Author(s):  
Himangshu Barman ◽  
Soujita Pramanik ◽  
Gargi Nandy ◽  
Sampa Banerjee ◽  
Gautam Aditya
Keyword(s):  
Spatial Distribution ◽  
Vertical Distribution ◽  
Shell Length ◽  
Land Snail ◽  
Shell Morphology ◽  
Shell Shape ◽  
Regression Equations ◽  
Growth Strategies ◽  
Shell Weight ◽  
Significant Difference

The spatial distribution and morphological features of the land snail Succinea baconi (Pfeiffer, 1854) (Gastropoda: Succineidae) from India were evaluated. The survey performed in gardens and bushes in Coochbehar, West Bengal, India, has made it possible to assess the abundance of the snail S. baconi on the randomly selected lemon plants (n = 18). Logistic regressions were employed to judge differences in vertical distribution, resource association and size class variation in the snails under study. Variation in shell morphology was assessed by performing the regression analysis of the sampled shells of live snails (n = 258) and vacant shells of the deceased individuals (n = 100). An overall significant difference (p < 0.05) in the vertical distribution of snails in lemon plants was observed. As to their association with resources available, snails were found to be more abundant in detritus than on living parts of the plants. The performed logistic regression revealed that the relative abundance of different S. baconi size classes was significantly different (p < 0.001). Significant correlations (p < 0.001) were found among different body size variables, with the shell length (x)-body weight (y) relationship being: y = 0.232x2.524 (for live snails) and the shell length (x)-shell weight (y) relationship being: y = 0.358x2.537 (for shells of dead snails). Various parameters of the snail shell shape could be represented through regression equations. Although reproduction and growth strategies of snails need to be explored further, the presented observations improve our understanding of the ecology of S. baconi, which may prove useful for future conservation efforts.

Shell variations in the gastropod, Monodonta labio, in the North-western Pacific: the important role of temperature in the evolution process

2019 ◽  
Vol 99 (7) ◽  
pp. 1591-1599
Author(s):  
Dan Zhao ◽  
Ling-Feng Kong ◽  
Takenori Sasaki ◽  
Qi Li
Keyword(s):  
Environmental Gradients ◽  
Ecological Factors ◽  
Local Maximum ◽  
Morphological Diversity ◽  
Shell Shape ◽  
Shape Variation ◽  
Genetic Structuring ◽  
Morphological Variations ◽  
China Sea

AbstractMolluscan shells showing phenotypic variations are ideal models for studying evolution and plasticity. In north-eastern Asia, genetic and morphological diversity of the gastropod, Monodonta labio, were assumed to be influenced by both palaeoclimatic changes and current ecological factors. In this study, we examined spatial variations in shell shape of M. labio using general measurement and geometric morphometric analysis. We also investigated whether shell shape variation is best explained by environmental gradients or by genetic structuring, based on our prior molecular phylogeographic study. Two common morphological forms were observed among Chinese populations and in the adjacent Asian areas. Both the analyses revealed separation patterns in morphological variations of shell shape among the clades and populations. Environmental modelling analysis showed a significant correlation between shape variations and local maximum temperatures of the warmest month, indicating the role of natural selection in the evolution of this species. Data obtained in this study, combined with the cytochrome oxidase subunit I (COI) molecular phylogenetic data from the prior study, showed that morphological variations in M. labio were constrained by both local adaptation and phenotypic plasticity. We hypothesized that geographic separation by the Dongshan Landbridge was the first step towards its diversification, and that the temperature gradient between the East China Sea and South China Sea probably was the selective force driving the divergence of its morphological variations.

scholarly journals Adaptive divergence in shell morphology in an ongoing gastropod radiation from Lake Malawi

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Bert Van Bocxlaer ◽  
Claudia M. Ortiz-Sepulveda ◽  
Pieter R. Gurdebeke ◽  
Xavier Vekemans
Keyword(s):  
Common Garden ◽  
Shell Morphology ◽  
Model Systems ◽  
Shell Shape ◽  
Adaptive Divergence ◽  
Nominal Species ◽  
Shape Variation ◽  
In The Wild ◽  
Evolutionary Radiations ◽  
Contrasting Habitats

Abstract Background Ecological speciation is a prominent mechanism of diversification but in many evolutionary radiations, particularly in invertebrates, it remains unclear whether supposedly critical ecological traits drove or facilitated diversification. As a result, we lack accurate knowledge on the drivers of diversification for most evolutionary radiations along the tree of life. Freshwater mollusks present an enigmatic example: Putatively adaptive radiations are being described in various families, typically from long-lived lakes, whereas other taxa represent celebrated model systems in the study of ecophenotypic plasticity. Here we examine determinants of shell-shape variation in three nominal species of an ongoing ampullariid radiation in the Malawi Basin (Lanistes nyassanus, L. solidus and Lanistes sp. (ovum-like)) with a common garden experiment and semi-landmark morphometrics. Results We found significant differences in survival and fecundity among these species in contrasting habitats. Morphological differences observed in the wild persisted in our experiments for L. nyassanus versus L. solidus and L. sp. (ovum-like), but differences between L. solidus and L. sp. (ovum-like) disappeared and re-emerged in the F1 and F2 generations, respectively. These results indicate that plasticity occurred, but that it is not solely responsible for the observed differences. Our experiments provide the first unambiguous evidence for genetic divergence in shell morphology in an ongoing freshwater gastropod radiation in association with marked fitness differences among species under controlled habitat conditions. Conclusions Our results indicate that differences in shell morphology among Lanistes species occupying different habitats have an adaptive value. These results also facilitate an accurate reinterpretation of morphological variation in fossil Lanistes radiations, and thus macroevolutionary dynamics. Finally, our work testifies that the shells of freshwater gastropods may retain signatures of adaptation at low taxonomic levels, beyond representing an evolutionary novelty responsible for much of the diversity and disparity in mollusks altogether.

scholarly journals Systematics of Ariantinae (Gastropoda, Pulmonata, Helicidae), a new approach to an old problem

2016 ◽  
Vol 85 (1) ◽  
pp. 37-65l ◽  
Author(s):  
Dick S.J. Groenenberg ◽  
Peter Subai ◽  
Edmund Gittenberger
Keyword(s):  
Sequence Data ◽  
Taxonomic Status ◽  
Proximal Part ◽  
Sister Group ◽  
Shell Morphology ◽  
Shell Shape ◽  
Dna Sequence Data ◽  
Starting Point ◽  
Combining Data ◽  
The Individual

A new starting-point in Ariantinae systematics is presented by combining data on traditional shell morphology and genital anatomy, with phylogeny reconstructions based on DNA sequence data. For nearly all genera and subgenera one or more shells are depicted and drawings of the proximal part of the genital organs are shown to illustrate the morphological diversification within the subfamily. For as much as our material allowed it, partial sequences are presented for Histone H3 (H3), Cytochrome c oxidase subunit I (COI), Cytochrome B (CytB) and 16S ribosomal RNA (16S). Some of the allegedly speciose genera like Chilostoma and Campylaea (Zilch, 1960) do not represent monophyletic groups of species, whereas most of the remaining nominal taxa (e.g. Causa, Dinarica, Josephinella, Faustina, Liburnica, Kosicia and Thiessea) warrant a separate taxonomic status indeed. Sequence data from individual markers were informative at the species-level, but not for higherlevel phylogenetics. Insight in genus-level relationships was obtained after concatenation of the individual datasets. The Ariantinae are estimated to have originated during the late Cretaceous (Campanian), not later than ca. 80 million years ago. The enigmatic and morphologically aberrant, monotypic genus Cylindrus is shown as the sister-group of Arianta, a genus including A. arbustorum, which is also unusual in shell-shape and habitat. Ariantopsis and Wladislawia are classified as subgenera of neither Campylaea nor Chilostoma, but Cattania. Sabljaria is considered a subgenus of Dinarica. The nominal genus Superba is shown to be paraphyletic; additional data should demonstrate whether Superba has to be synonymised with Liburnica. The Ariantinae are here divided in 21 genera (2 new) and 13 subgenera (3 new).

scholarly journals Impact of seawater <i>p</i>CO<sub>2</sub> on calcification and Mg/Ca and Sr/Ca ratios in benthic foraminifera calcite: results from culturing experiments with <i>Ammonia tepida</i>

2010 ◽  
Vol 7 (1) ◽  
pp. 81-93 ◽  
Author(s):  
D. Dissard ◽  
G. Nehrke ◽  
G. J. Reichart ◽  
J. Bijma
Keyword(s):  
Carbon Dioxide ◽  
Calcium Carbonate ◽  
Benthic Foraminifera ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Planktonic Foraminifera ◽  
Ambient Conditions ◽  
Precipitated Calcium Carbonate ◽  
Shell Weight ◽  
Dissolved Carbon

Abstract. Evidence of increasing concentrations of dissolved carbon dioxide, especially in the surface ocean and its associated impacts on calcifying organisms, is accumulating. Among these organisms, benthic and planktonic foraminifera are responsible for a large amount of the globally precipitated calcium carbonate. Hence, their response to an acidifying ocean may have important consequences for future inorganic carbon cycling. To assess the sensitivity of benthic foraminifera to changing carbon dioxide levels and subsequent alteration in seawater carbonate chemistry, we cultured specimens of the shallow water species Ammonia tepida at two concentrations of atmospheric CO2 (230 and 1900 ppmv) and two temperatures (10 °C and 15 °C). Shell weights and elemental compositions were determined. Impact of high and low pCO2 on elemental composition are compared with results of a previous experiment were specimens were grown under ambient conditions (380 ppvm, no shell weight measurements of specimen grown under ambient conditions are, however, available). Results indicate that shell weights decrease with decreasing [CO32−], although calcification was observed even in the presence of calcium carbonate under-saturation, and also decrease with increasing temperature. Thus both warming and ocean acidification may act to decrease shell weights in the future. Changes in [CO32−] or total dissolved inorganic carbon do not affect the Mg distribution coefficient. On the contrary, Sr incorporation is enhanced under increasing [CO32−]. Implications of these results for the paleoceanographic application of foraminifera are discussed.

Morphometric relationships and relative growth of Hexaplex trunculus and Bolinus brandaris (Gastropoda: Muricidae) from the Ria Formosa lagoon (southern Portugal)

2015 ◽  
Vol 96 (7) ◽  
pp. 1417-1425 ◽  
Author(s):  
Paulo Vasconcelos ◽  
Carlos M. Barroso ◽  
Miguel B. Gaspar
Keyword(s):  
Shell Length ◽  
Morphological Plasticity ◽  
Shell Shape ◽  
Shell Weight ◽  
Geometric Morphometric ◽  
Relative Growth ◽  
Ria Formosa ◽  
Hexaplex Trunculus ◽  
Southern Portugal ◽  
Bolinus Brandaris

The present study reports morphometric relationships and discusses the relative growth in the banded murex (Hexaplex trunculus) and the purple dye murex (Bolinus brandaris) from the Ria Formosa lagoon (southern Portugal). A total of 11 morphometric parameters (eight linear variables: shell length, shell width, total aperture length, aperture length, aperture width, spire length, spire width and siphonal canal length; three ponderal variables: total weight, soft parts weight and shell weight) were analysed in both species. The analyses comprised numerous individuals of both sexes and with broad size ranges (H. trunculus: 10.7–82.8 mm shell length; B. brandaris: 14.6–107.7 mm shell length), fairly representative of the populations from the Ria Formosa lagoon. In general, B. brandaris exhibited greater morphological plasticity and higher variability in shell shape compared with H. trunculus. In both species, the vast majority of morphometric relationships displayed positive allometries, distantly followed by negative allometries and by isometries. Although H. trunculus and B. brandaris are known to lack external sexual dimorphism, several morphometric relationships revealed significant differences in the type of growth between sexes, which should be further confirmed using more powerful techniques, such as geometric morphometric analyses of shell shape.

Ontogenetic change and intra-specific variation of shell morphology in the Cretaceous nautiloid (Cephalopoda, Mollusca) Eutrephoceras clementinum (d'Orbigny, 1840) from the Ariyalur area, southern India

2009 ◽  
Vol 83 (3) ◽  
pp. 365-378 ◽  
Author(s):  
Ryoji Wani ◽  
Krishnan Ayyasami
Keyword(s):  
Shell Morphology ◽  
Southern India ◽  
Shell Shape ◽  
Morphometric Study ◽  
Central Position ◽  
Ontogenetic Change ◽  
Allometric Relationship ◽  
Shell Diameter ◽  
Mode Of Life ◽  
Specific Variation

Morphometric analyses of shell morphology in the Cretaceous nautiloid Eutrephoceras clementinum (d'Orbigny, 1840) (Cephalopoda, Mollusca) from the Ariyalur area, southern India, reveal ontogenetic change from hatching to maturity as well as intra-specific variation in shell morphology. the shell breadth has a negative allometric relationship with shell diameter and with whorl height, and the umbilicus diameter has a positive allometric relationship with shell diameter. This shows that shell shape became relatively thinner with less variation, and the umbilicus diameter became relatively broader with growth. the siphuncle position moves from a dorso-central to ventro-central position with growth. A constriction was recognized on the early whorl at 20 mm in shell diameter, and the interval angles of succeeding septa were changed at the 8th septum, indicating that they hatched at this stage. the bending of umbilical walls of apertures toward the center of coiling suggests that E. clementinum attained maturity at about 115 mm in shell diameter. the comparison of the shell morphology of E. clementinum with that of E. bouchardianum (d'Orbigny, 1840) reported in the literature clarifies their difference in whorl shape and umbilical size, especially in the adult stage. This kind of morphometric study of nautiloids is essential for elucidating their adaptive designs for environment and mode of life, functional shell morphology, taxonomy, phylogeny, and evolution.

scholarly journals Morphological shell variation of Zidona dufresnei (Caenogastropoda: Volutidae) from the Southwestern Atlantic Ocean

2020 ◽  
Vol 33 (1) ◽  
pp. 53-68
Author(s):  
Alonso I. Medina ◽  
María Alejandra Romero ◽  
Augusto Crespi-Abril ◽  
Maite A. Narvarte
Keyword(s):  
Atlantic Ocean ◽  
San Antonio ◽  
Maximum Size ◽  
Shell Morphology ◽  
Shell Shape ◽  
Southwestern Atlantic ◽  
Shape Variation ◽  
Fishery Resource ◽  
Southwestern Atlantic Ocean ◽  
Shape And Size

The volutid gastropod Zidona dufresnei is an important fishery resource from the Southwestern Atlantic Ocean. This species exhibits strong interpopulation differences in life history features, which lead to postulate the existence of two morphotype ('normal' and 'dwarf'). In this study, we combine and compare traditional and geometric morphometrics to capture shell shape variation of Z. dufresnei among three populations from Mar del Plata (37° S) to San Matías Gulf (42° S) to test the hypothesis that the phenotypic variation already described in the life cycle and size is also expressed in the shell shape. Significant differences in the shell morphology among these three populations were detected, mainly associated to the maximum size of individuals and shell shape. The Bahía San Antonio morphotype had shells with higher general roundness and weight compared to San Matías Gulf and Mar del Plata morphotypes, which were not differentiated. Our results support the hypothesis of Lahille (1895) who distinguished the morphotype of Bahía San Antonio ('dwarf' morphotype) as Voluta angulata affinis. The functional significance of the variability found is discussed in terms of the ecological and genetic effects on shape and size.

Factors Influencing Shell Shape in the Mussel Mytilus Edulis

1968 ◽  
Vol 48 (3) ◽  
pp. 561-584 ◽  
Author(s):  
R. Seed
Keyword(s):  
Mytilus Edulis ◽  
Slow Growth ◽  
Shell Height ◽  
Shell Morphology ◽  
Population Variation ◽  
Shell Shape ◽  
Factors Influencing ◽  
High Incidence ◽  
Local Variability ◽  
Transplantation Experiments

An attempt is made to explain the great variations in gross shell morphology noted in field populations of Mytilus edulis.In any one mussel population, variation in shell form can be attributed to differences in age, old mussels having proportionately heavier shells where width often exceeds shell height. This is invariably accompanied by down-turned, divergent umbones and varying degrees of incurvature of the ventral shell margin.Variations in the age structure of mussel populations from different habitats can also account for local variability in shell morphology. Localities where the life expectancy of mussels is increased due to absence of predators (especially in the upper shore) reveal a high incidence of old ‘ungulate’ individuals, whereas populations in which the mussel turnover is more rapid show a preponderance of relatively young mussels.Shell morphology is greatly influenced by growth rate and density. These probably exert their effect through physical compression which is maximum in localities of fast growth and high density and least in areas of slow growth and low density. High compression leads to an elongate form whereas low compression results in higher, more triangular shaped shells. Growth rates and densities, even within the same habitat, are, however, exceedingly variable.Since all environmental conditions vary in both time and space, wide variation in shell morphology is to be expected, even in animals from the same locality.Transplantation experiments indicate that variation in shell morphology is essentially phenotypic, older animals being more likely to exhibit a form which is characteristic of their particular habitat. Smaller mussels from widely different habitats show remarkable similarity in shell morphology.

Shifts in shell mineralogy and metabolism of Concholepas concholepas juveniles along the Chilean coast

2015 ◽  
Vol 66 (12) ◽  
pp. 1147 ◽  
Author(s):  
Laura Ramajo ◽  
Alejandro B. Rodríguez-Navarro ◽  
Carlos M. Duarte ◽  
Marco A. Lardies ◽  
Nelson A. Lagos
Keyword(s):  
Coastal Upwelling ◽  
Seawater Temperature ◽  
Mineralogical Composition ◽  
Saturation State ◽  
Tropical Zone ◽  
Chilean Coast ◽  
Marine Snails ◽  
Consumption Rates ◽  
Concholepas Concholepas ◽  
Freshwater Inputs

Along the west coast of South America, from the tropical zone to the Patagonian waters, there is a significant latitudinal gradient in seawater temperature, salinity and carbonate chemistry. These physical–chemical changes in seawater induce morphological and physiological responses in calcifying organisms, which may alter their energy budget and calcification processes. In this study, we study the organism energy maintenance (i.e. metabolic rate) and mineralogical composition of the shell of the juvenile marine snails Concholepas concholepas (Gastropoda: Muricidae), collected from benthic populations located ~2000km apart, varies across geographic regions along the Chilean coast. We found that in juvenile snails, the calcite:aragonite ratio in the pallial shell margin (i.e. newly deposited shell) increase significantly from northern to southern populations and this increase in calcite precipitation in the shell of juveniles snails was associated with a decrease in oxygen consumption rates in these populations. Our result suggests that calcite secretion may be favoured when metabolic rates are lowered, as this carbonate mineral phase might be less energetically costly for the organism to precipitate. This result is discussed in relation to the natural process such as coastal upwelling and freshwater inputs that promote geographic variation in levels of pH and carbonate saturation state in seawater along the Chilean coast.

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