scholarly journals Covariations between Shell-Growth Parameters and the Control of the Ranges of Variation of Functionally Relevant Shell-Shape Parameters in Bivalves: A Theoretical Approach

2014 ◽  
Vol 2014 ◽  
pp. 1-8
Author(s):  
Jean Béguinot
Keyword(s):  
Growth Parameters ◽  
Shell Growth ◽  
Practical Interest ◽  
Theoretical Background ◽  
Shell Shape ◽  
Shape Parameters ◽  
Functional Parameters ◽  
Intraspecific Variations ◽  
Adaptive Constraints ◽  
Geometrical Relationships

Major traits of shell shape in bivalves may alternatively be described in terms of (i) functionally relevant parameters, assumed to play a significant role in the adaptation of bivalves molluscs to their environments (such as the shell-outline elongation E, ventral convexity K, and dissymmetry D), or (ii) growth-based parameters, directly controlled by the animal. Due to the geometrical linkage between functionally-relevant and growth-based parameters, adaptive constraints that may either widen or narrow the respective ranges of variations of the functional parameters lead to the onset of specific covariations (either positive or negative) between the growth-based parameters. This has practical interest since adaptive constraints are often difficult to identify directly, while they can be conveniently inferred indirectly via the easily recorded patterns of covariances between growth-based parameters. Hereafter, I provide the theoretical background of this tool, including (1) establishing the geometrical relationships between growth-based and functionally relevant parameters and (2) then specifying the correspondences between the different patterns of adaptive constraints, widening or narrowing the variations of the functional parameters and the corresponding patterns of covariations between the growth-based parameters. Illustrative examples of the practical use of this tool are provided, considering both interspecific and intraspecific variations within marine and fresh-water clams.

scholarly journals Covarying Shell Growth Parameters and the Regulation of Shell Shape in Marine Bivalves: A Case Study on Tellinoidea

2014 ◽  
Vol 2014 ◽  
pp. 1-10
Author(s):  
Jean Béguinot
Keyword(s):  
Growth Parameters ◽  
Shell Growth ◽  
Shell Shape ◽  
Shape Parameters ◽  
Bivalve Molluscs ◽  
Severe Limitation ◽  
Interspecific Variability ◽  
Marine Bivalves ◽  
Shape Descriptions

Specific parameters characterising shell shape may arguably have a significant role in the adaptation of bivalve molluscs to their particular environments. Yet, suchfunctionally relevantshape parameters (shell outline elongation, dissymmetry, and ventral convexity) are not those parameters that the animal may directly control. Rather than shell shape, the animal regulates shell growth. Accordingly, an alternative,growth-baseddescription of shell-shape is best fitted to understand how the animal may control the achieved shell shape. The key point is, in practice, to bring out the link between those two alternative modes of shell-shape descriptions, that is, to derive the set of equations which connects thegrowth-basedshell-shape parameters to thefunctionally relevantshell-shape parameters. Thus, a preliminary object of this note is toderivethis set of equations as a tool for further investigations. A second object of this work is to provide an illustrative example of implementation of this tool. I report on an unexpected negative covariance between growth-based parameters and show how this covariance results in a severe limitation of the range of interspecific variability of the degree of ventral convexity of the shell outline within the superfamily Tellinoidea. Hypotheses are proposed regarding the constraints possibly at the origin of this limitation of interspecific variability.

scholarly journals Unexpected Covariances between Shell Growth Parameters are Controlling the Range of Interspecific Variations of Shell shape in the Deep-Sea Clams Genus Calyptogena (Bivalvia: Veneroida)

2018 ◽  
pp. 1-13
Author(s):  
Jean Béguinot
Keyword(s):  
Environmental Conditions ◽  
Deep Sea ◽  
Growth Parameters ◽  
Shell Growth ◽  
Niche Differentiation ◽  
Interspecific Variation ◽  
Shell Shape ◽  
Shallow Waters ◽  
Mechanical Resistance ◽  
Interspecific Variations

In Bivalves, shell shape descriptors (in particular, elongation E, dissymmetry D, ventral convexity K) are considered functionally-relevant parameters, each of them likely being exposed to specific selective pressures, according to environmental conditions. Indeed, previous investigations, have repeatedly confirmed that different types of constraints do apply to the respective ranges of interspecific variations of E, D, K: in particular, a trend for a substantially extended range of interspecific variation of shell-elongation E (likely attributed to niche differentiation) and, on the contrary, a trend for a severely restricted range of interspecific variation of ventral-convexity K (closely centered at an optimum for mechanical resistance of valves). In turn, due to rigid geometrical relationships linking shell-shape to shell-growth, this pattern of constraints on shell-shape variations implies, mathematically, the occurrence of specifically associated covariances between shell-growth parameters, the occurrence of which were, indeed, repeatedly observed within all groups of shallow-waters clams examined so far. Yet, the fairly different environmental conditions prevailing at bathyal / abyssal depths invite addressing comparatively some typically deep-sea clams; hereafter the genus Calyptogena. Contrary to expectation, the same types of covariances between shell-growth parameters are reported in deep-sea Calyptogena as those reported in shallow-waters clams, thus suggesting less dissimilar patterns of constraints than expected between shallow waters and deep-sea conditions.

scholarly journals The Spatial Heterogeneity of the Black Scorpionfish, Scorpaena porcus (Scorpaenidae): Differences in Length, Dietary and Age Compositions

2021 ◽  
Vol 11 (24) ◽  
pp. 11919
Author(s):  
Josipa Ferri ◽  
Sanja Matić-Skoko
Keyword(s):  
High Selectivity ◽  
Adriatic Sea ◽  
Multivariate Analyses ◽  
Growth Parameters ◽  
Island Area ◽  
Intraspecific Variations ◽  
Geographical Scale ◽  
Diet Analyses ◽  
Slow Growing ◽  
Scorpaena Porcus

The present study assessed spatial variations in several biological characteristics of Scorpaena porcus Linnaeus, 1758 and estimated length structure, dietary composition and growth parameters for the species. Sampling was carried out in two areas, about 200 km apart, in the coastal Adriatic Sea, which is the northernmost region of the Mediterranean. A total of 388 specimens of S. porcus were caught, 233 from the Split area and 155 from the Pag Island area, and a higher proportion of individuals in the ≤15 cm length classes were found in the Split area. The results of the age, growth and diet analyses demonstrated that the black scorpionfish is a slow-growing and long-lived species that feeds on a wide variety of plant and animal taxa and shows a high selectivity for crustacean decapods. Detailed comparisons and multivariate analyses showed significant fine-scale spatial structuring of the investigated species, as observed length, dietary and age compositions were heterogeneous among the two areas. Fish from the Pag Island area ingested a greater diversity of the prey types, fed to a greater extent on fishes, reached the highest total length and showed a higher growth rate. Such intraspecific variations could reflect adaptations to different environmental conditions and support the geographical scale at which local black scorpionfish populations should be managed.

What is gradualism? Cryptic speciation in globorotaliid foraminifera

Paleobiology ◽  
1996 ◽  
Vol 22 (3) ◽  
pp. 386-405 ◽  
Author(s):  
Richard D. Norris ◽  
Richard M. Corfield ◽  
Julie Cartlidge
Keyword(s):  
Reproductive Isolation ◽  
Morphological Changes ◽  
Morphological Evolution ◽  
Reproductive Ecology ◽  
Shell Growth ◽  
Shell Shape ◽  
Planktic Foraminifera ◽  
Near Surface ◽  
Surface Ocean ◽  
Speciation Event

Analysis of the evolution of the Globorotalia (Fohsella) lineage of planktic foraminifera suggests that reproductive ecology and shell shape have evolved independently in this group. The silhouette of fohsellid shells displays a nearly unbroken anagenetic trend, yet isotopic data show that the fohsellids changed their depth of reproduction during the anagenetic evolution of their skeletons. Remarkably, there are no correlations between anagenesis in skeletal shape and the establishment of reproductive isolation. Apparently, anagenesis masks at least one speciation event that is apparent only in the isotopic evidence for a change in reproductive ecology. Although anagenetic trends have been widely cited as evidence for gradual speciation in planktic foraminifera and other microfossil groups, our data suggest that they should not always be considered to record either the tempo or mode of speciation.Speciation was apparently uncoupled from morphological evolution in fohsellids because these evolutionary phenomena occurred in different phases of ontogeny. Gradual morphological changes were associated with the main phase of shell growth of both the ancestor and descendant species in the near-surface ocean. Reproductive isolation occurred when ancestral and descendant populations became established at different depths near the end of the life cycle. Morphological evolution may also be uncoupled from reproductive isolation in other organisms that experience very different selection pressures over the duration of their ontogenies, such as parasites with many hosts, species with multiple phases of metamorphosis, and organisms that broadcast their gametes.

scholarly journals Age and growth variability of the yellow clam (Mesodesma mactroides) in two populations from Argentina: implications under climate change

2020 ◽  
Vol 98 (7) ◽  
pp. 481-494
Author(s):  
M.C. Risoli ◽  
A. Baldoni ◽  
J. Giménez ◽  
B.J. Lomovasky
Keyword(s):  
Climate Change ◽  
Cross Sections ◽  
Growth Rates ◽  
Growth Parameters ◽  
Shell Growth ◽  
Condition Index ◽  
Age And Growth ◽  
Shell Mass ◽  
Growth Variability ◽  
Two Populations

Morphometric relationships and age and growth rates of the yellow clam (Mesodesma mactroides Reeve, 1854 = Amarilladesma mactroides (Reeve, 1854)) were compared in two populations from Argentina: Santa Teresita (36°32′00″S) and Mar del Plata (37°57′52″S). The Santa Teresita clams were heavier (shell, soft parts) than the Mar del Plata clams. Cross sections stained with Mutvei’s solution and acetate peels revealed an internal shell growth pattern of well-defined slow-growing translucent bands and alternating fast-growing opaque bands. Translucent bands (clusters) representing external rings were formed mostly during October in both sites, coinciding with gonadal maturation processes and spawning. Data confirm the annual formation of translucent bands in this species. Comparison of growth parameters showed a higher growth rate k and lower maximum age in Mar del Plata (8 years) than in Santa Teresita (9 years), which could be triggered by differences in salinity between localities due to the influence of the Rio de la Plata estuary, which is strongly linked to climate variability. Shell mass condition index and Oceanic Niño Index were negatively correlated, showing the influence of El Niño in shell properties of the species. Considering that events are becoming more intense and frequent, changes in growth rates and shell properties of Santa Teresita’s population could be expected to be more vulnerable under climate change.

scholarly journals Alternative models for allozyme-associated heterosis in the marine bivalve Spisula ovalis.

Genetics ◽  
1995 ◽  
Vol 139 (4) ◽  
pp. 1719-1726 ◽  
Author(s):  
P David ◽  
B Delay ◽  
P Berthou ◽  
P Jarne
Keyword(s):  
Genetic Basis ◽  
Linear Models ◽  
Growth Parameters ◽  
Shell Growth ◽  
Maximum Size ◽  
Age And Growth ◽  
Individual Growth ◽  
Marine Bivalve ◽  
Initial Growth ◽  
Genomic Effects

Abstract Correlations between allozyme heterozygosity and fitness-related traits, especially growth, have been documented in natural populations of marine bivalves. However, no consistent pattern has been exhibited, because heterotic effects on size vary with age and individual growth parameters are generally unknown. No consensus has emerged on the genetic basis of allozyme-associated heterosis. The species studied here, Spisula ovalis, displays annual shell growth lines, which allows us to compute individual age and growth dynamics over the whole life span. Our morphological study was coupled to a protein electrophoresis study at seven polymorphic loci. While the maximum size gained is not related to heterozygosity, the age at half maximum size, t1/2, is significantly negatively correlated with heterozygosity, indicating an heterotic effect on initial growth. The correlation between heterozygosity and size is expected to vanish when age increases, due to the form of the growth function. This decreasing correlation is consistent with previous studies. We compare the relative performances of five linear models to analyze the genetic basis of heterosis. Surprisingly, the largest part of variance in t1/2 is due to additive effects, the overdominant components being much weaker. Heterosis is therefore due to general genomic effects rather than to local overdominance restricted to allozymes or small neighboring chromosomal segments. A significant dependence of individual heterotic contributions of the enzyme loci upon expected heterozygosities, rather than metabolic function, further supports the hypothesis of enzymes acting as markers. General genomic effects can hold only if allozyme heterozygosity is positively correlated with heterozygosity at fitness-related genes scattered throughout the genome. This hypothesis is supported here by heterozygosity correlations between enzymatic loci.

scholarly journals Validated age, growth, and mortality estimates of the ocean quahog (Arctica islandica) in the western Atlantic

2006 ◽  
Vol 64 (1) ◽  
pp. 31-38 ◽  
Author(s):  
Raouf W. Kilada ◽  
Steven E. Campana ◽  
Dale Roddick
Keyword(s):  
Atomic Bomb ◽  
Growth Parameters ◽  
Shell Growth ◽  
Arctica Islandica ◽  
Western Atlantic ◽  
Instantaneous Rate ◽  
Growth Increments ◽  
Age Frequency Distribution ◽  
Mortality Estimates ◽  
Age Estimates

Abstract Kilada, R. W., Campana S. E., and Roddick, D. 2007. Validated age, growth, and mortality estimates of the ocean quahog (Arctica islandica) in the western Atlantic. ICES Journal of Marine Science, 64: 31–38. The age structure of offshore (Sable Bank) and inshore (St Mary's Bay) populations of eastern Canadian ocean quahogs (Arctica islandica), and of a northwestern Iceland population, is investigated. Age estimates for eastern Canadian ocean quahogs were validated through analysis of bomb-produced 14C in quahog shell growth increments deposited before, during, and after the atmospheric atomic bomb testing periods of the 1950s and 1960s. Delta 14C from shells with presumed birthdates between the late 1950s and 1970s clearly reflects the sharp increase in oceanic radiocarbon attributable to nuclear testing. The results validate our age interpretations of Sable Bank quahogs to an age of 45 y, and support longevity estimates of more than 200 y for the same population. Longevity calculations for the other populations exceeded 60 y. Von Bertalanffy growth parameters were estimated for the three populations; the growth rate of all three was relatively rapid for the first 20–30 y of life, but thereafter was very slow. The instantaneous rate of natural mortality (M), calculated using the age–frequency distribution of the unexploited populations, was estimated to be 0.03 and 0.10 for the Sable Bank and St Mary's Bay populations, respectively.

Age and growth of the queen scallop, Equichlamys bifrons, in the D'Entrecasteaux Channel and Huon River Estuary, Tasmania

1995 ◽  
Vol 46 (8) ◽  
pp. 1127 ◽  
Author(s):  
BM Wolf ◽  
RWG White
Keyword(s):  
Growth Parameters ◽  
Growth Ring ◽  
Shell Growth ◽  
River Estuary ◽  
Growth Patterns ◽  
Age And Growth ◽  
Growth Rings ◽  
Size Frequency Distribution ◽  
Size Frequency ◽  
Deep Bay

Growth of the queen scallop, Equichlamys bifrons, was examined at one site in the D'Entrecasteaux Channel and two sites in the Huon River estuary (Tasmania) by analysing growth rings on the shell and shell hinge ligament, tagging scallops, and using size-frequency techniques. Regular sampling of scallops revealed that shell growth of E. bifrons is seasonal, commencing in late spring and stopping in late autumn. During the remainder of the year, when the water temperature is below ~13�C, shell growth slows or stops and growth rings are formed on the shell and shell hinge ligament. The growth rings on the shell and hinge ligament of E. bifrons were verified as being annual by studying the growth of marked scallops. Long-term growth patterns were similar for E. bifrons from Middleton (D'Entrecasteaux Channel) and from Deep Bay (Huon River estuary). Tagging data collected over the 1992-93 growing season indicated short-term variation in growth between sites. Size-frequency distributions from Middleton and Deep Bay could not be interpreted because smaller scallops were scarce. Smaller size classes were present at Eggs and Bacon Bay (Huon River estuary) and the size-frequency distribution was resolved into age classes. Reasonable agreement was found between the von Bertalanffy growth parameters obtained from the size frequency, tagging, and growth ring data.

Growth of Lampsilis radiata (Bivalvia: Unionidae) in Sand and Mud: A Reciprocal Transplant Experiment

1986 ◽  
Vol 43 (3) ◽  
pp. 548-552 ◽  
Author(s):  
Scott G. Hinch ◽  
Robert C. Bailey ◽  
Roger H. Green
Keyword(s):  
Growth Rate ◽  
Shape Change ◽  
Unit Length ◽  
Shell Growth ◽  
Shell Shape ◽  
Transplant Experiment ◽  
Reciprocal Transplant Experiment ◽  
Rate Analysis ◽  
Two Populations

To examine the effects of habitat on shell growth and form, freshwater unionid clams (Lampsilis radiata) were reciprocally transplanted between a sandy and a muddy site in Inner Long Point Bay, Lake Erie. There were significant differences in the initial shell dimensions of the two populations, with the sand clams being larger and less obese than the mud clams. Pretransplant growth rate analysis, using annual rings, showed that long-term growth in the sand was greater than that in the mud. After 16 wk the transplanted clams were recovered. Overall growth rate was affected by the source of the clams, while transplant destination affected shape change (height growth per unit length growth). This suggests that shell growth rates may be under direct genetic control, while shell shape can be adaptively modified by environmental cues.

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