scholarly journals Objectively measuring subjectively described traits: geographic variation in body shape and caudal coloration pattern within Vieja melanura (Teleostei: Cichlidae)

2017 ◽  
Vol 65 (2) ◽  
Author(s):  
Caleb D. McMahan ◽  
Justin Kutz ◽  
Christopher Murray ◽  
Prosanta Chakrabarty ◽  
Aaron Geheber ◽  
...  
Keyword(s):  
Geographic Variation ◽  
Body Shape ◽  
Population Level ◽  
Phylogeographic Structure ◽  
Shape Variation ◽  
Southern Mexico ◽  
Geometric Morphometric ◽  
Morphometric Analyses ◽  
Mitochondrial Cytochrome B ◽  
Riverine Habitats

Vieja melanura is a Neotropical cichlid occurring in the Petén-lake district systems of Guatemala, as well as the Río Grijalva-Usumacinta basin, and other systems in Southern México, Belize, and Guatemala. A caudal stripe, extending forward from the caudal peduncle, is characteristic of this species. This stripe is sloped downward in nearly all individuals of V. melanura, but the degree of the slope is highly variable throughout its range. The slope and shape of the stripe has previously been used in diagnosing and differentiating between species of Vieja. The purpose of this study was to use objective methods to investigate morphological variation in the caudal stripe and body shape throughout the range of V. melanura. We studied geometric morphometric analyses of body shape and empirical measurements of the slope of the caudal stripe in 215 specimens of V. melanura. We also used the mitochondrial cytochrome b marker to study population level patterns within V. melanura. Results from our analyses showed significant geographic variation in body shape and patterns of coloration with little mitochondrial phylogeographic structure. These patterns likely correspond to differences in riverine habitats throughout the species’ distribution. In conclusion, these results can be used to inform other studies of color and shape variation as it applies to taxonomy and systematics.

Tissue preservation can affect geometric morphometric analyses: a case study using fish body shape

2019 ◽  
Vol 188 (1) ◽  
pp. 148-162 ◽  
Author(s):  
Carmelo Fruciano ◽  
Dominik Schmidt ◽  
Marcia Maria Ramírez Sanchez ◽  
Witold Morek ◽  
Zamira Avila Valle ◽  
...  
Keyword(s):  
Body Shape ◽  
Canonical Variate ◽  
Shape Variation ◽  
Substantial Variation ◽  
Geometric Morphometric ◽  
Fresh Fish ◽  
Morphometric Analyses ◽  
Variate Analysis ◽  
Shape Data

Abstract In geometric morphometrics, the extent of variation attributable to non-biological causes (i.e. measurement error) is sometimes overlooked. The effects of this variation on downstream statistical analyses are also largely unknown. In particular, it is unclear whether specimen preservation induces substantial variation in shape and whether such variation affects downstream statistical inference. Using a combination of empirical fish body shape data and realistic simulations, we show that preservation introduces substantial artefactual variation and significant non-random error (i.e. bias). Most changes in shape occur when fresh fish are frozen and thawed, whereas a smaller change in shape is observed when frozen and thawed fish are fixed in formalin and transferred to ethanol. Surprisingly, we also show that, in our case, preservation produces only minor effects on three downstream analyses of shape variation: classification using canonical variate analysis, permutation tests of differences in means and computations of differences in mean shape between groups. Even mixing of differently preserved specimens has a relatively small effect on downstream analyses. However, we suggest that mixing fish with different preservation should still be avoided and discuss the conditions in which this practice might be justified.

scholarly journals Populations of Odontesthes (Teleostei: Atheriniformes) in the Andean region of Southern South America: body shape and hybrid individuals

2015 ◽  
Vol 13 (1) ◽  
pp. 137-150 ◽  
Author(s):  
Cecilia Conte-Grand ◽  
Julie Sommer ◽  
Guillermo Ortí ◽  
Víctor Cussac
Keyword(s):  
Morphometric Analysis ◽  
Body Shape ◽  
Distribution Area ◽  
Geometric Morphometric ◽  
Original Distribution ◽  
Morphometric Analyses ◽  
Diagnostic Characteristics ◽  
Lakes And Reservoirs ◽  
Odontesthes Hatcheri ◽  
High Degree

The original distribution area of the Patagonian 'pejerrey' Odontesthes hatcheri has been subjected to the introduction of a related species; the Bonaerensean 'pejerrey' Odontesthes bonariensis. This species currently coexists with O. hatcheri in lakes and reservoirs, and can interbreed and produce fertile hybrid offspring. The purposes of this study were; a) the extensive sampling of Patagonian and Andean-Cuyan populations of pejerrey, b) the species identification according to taxonomic key, c) validation of taxonomic results on the basis of mitochondrial DNA composition, and d) applying morphometric analysis to explore the effects of hybridization and environmental conditions on body shape. Cytochrome b sequence analysis showed a high degree of genetic divergence between species and low intraspecific variation in O. hatcheri. Geometric Morphometric Analyses detected shape differences in agreement with diagnostic characteristics of each species. Putative hybrids exhibiting intermediate diagnostic characteristics were identified by Geometric Morphometric Analysis. Significant regressions between body shape and total phosphorus and altitude were found, suggesting a dependence on trophic web structure. This multi-level approach suggests the introgression of O. bonariensis into several O. hatcheri populations throughout Patagonia. Managers should take this into account when considering further exotic introductions into regions where non-native fishes have not yet become established.

scholarly journals A geometric morphometric analysis of Arachnoides placenta (Echinoidea: Clypeasteroida): An examination of ontogenetic development and morphological variation

Zoosymposia ◽  
2019 ◽  
Vol 15 (1) ◽  
pp. 159-171
Author(s):  
ROBERT E. SWISHER ◽  
JIH-PAI LIN
Keyword(s):  
Developmental Change ◽  
Shape Change ◽  
Adult Life ◽  
Morphologic Change ◽  
Shape Variation ◽  
Minor Variation ◽  
Geometric Morphometric ◽  
Morphometric Analyses ◽  
Geometric Morphometric Analysis ◽  
Sand Dollars

Irregular echinoids, particularly clypeasteroids or “sand dollars”, have obtained highly adaptive morphologies suited to their life habitats. Specimens (n = 26) of a clypeasteroid echinoid Arachnoides placenta were examined to understand how these adaptive morphologies were ontogenetically and developmentally obtained. Ontogenetically, early post-larval juvenile specimens have a pentagonal morphologic outline (known as ambitus) that shifts to a circular or a sub-circular morphology observed in the largest adult specimens. Circular morphology appears optimized for the adult life habitat or niche. Both landmark and semilandmark geometric morphometric methodologies were applied to quantify shape change, ontogenetic variation, and developmental morphology in A. placenta. Ambitus change is concentrated along the interambulacral regions with broader curvature variations occurring across both ambulacral and interambulacral regions. Circular adult morphology was a result of non-isometric shape change concentrated anteriorly with minor variation around posterior margin/periproctal furrow. Interior morphologic change of the petaloids and periproct was also quantified, mainly impacting posterior outline morphology. Minimal deformation of the basicoronal plates was detected, indicating stability during ontogeny. Results indicated that complex, non-isometric allometric shape change, both along the ambitus and interiorly, is required to morph from a pentagonal outline in post-larval juveniles to a circular or sub-circular ambitus morphology in adults. This analysis demonstrates the advantages of both landmark and semilandmark geometric morphometric analyses for quantifying developmental change and shape variation in Clypeasteroida.

scholarly journals A quantitative approach to determine the taxonomic identity and ontogeny of the pycnodontiform fish Pycnodus (Neopterygii, Actinopterygii) from the Eocene of Bolca Lagerstätte, Italy

2018 ◽  
Author(s):  
John Joseph Cawley ◽  
Giuseppe Marrama ◽  
Giorgio Carnevale ◽  
Jürgen Kriwet
Keyword(s):  
Body Shape ◽  
Morphological Variability ◽  
Fish Fauna ◽  
Quantitative Approach ◽  
Meristic Characters ◽  
Geometric Morphometric ◽  
Nocturnal Feeding ◽  
Morphometric Analyses ◽  
Multiple Species ◽  
Large Adult

Background. The pycnodontiform fish Pycnodus is one of the representatives of the highly diverse actinopterygian fish fauna from the early Eocene Bolca Lagerstätte, representing one of the youngest and thus last occurrences of the extinct neopterygian clade Pycnodontiformes. This genus has historically been used as a wastebasket taxon in regards to poorly known pycnodontiform fossils and authors have argued over the specific status of the Bolca Lagerstätte Pycnodus in terms of how many species are contained within the genus with some arguing for multiple species and others suggesting lumping all Bolca specimens together into one species. Methods. Here, we use a quantitative approach performing biometric and geometric morphometric analyses on 39 specimens of Pycnodus in order to determine if the morphological variability within the sample might be related to inter- or intraspecific variation. Results. The analyses revealed that the variations of body shape, morphometric and meristic characters are continuous and cannot be used to distinguish different morphotypes. On the contrary, our results show a remarkable link between shape and size, related to ontogeny. Discussion. Differences in body shape of small (juvenile) and large (adult) individuals is probably related to different microhabitats occupation on the Bolca reef with juveniles sheltering within crevices on the reef and adults being more powerful swimmers that swim above the coral. There is no evidence of nocturnal feeding in this pycnodont as previously hypothesized. Taxonomically, we suggest that the Bolca Pycnodus should be referred to strictly as Pycnodus apodus as this was the name given to the holotype. Additionally, an overview of species assigned to Pycnodus is given.

Shape variation of the prawn Macrobrachium jelskii (Palaemonidae: Decapoda) in the Neotropical semiarid drainages: an intra- and inter-basin investigation

2021 ◽  
Vol 72 (1) ◽  
pp. 84
Author(s):  
Sávio A. S. N. Moraes ◽  
Carlos E. R. D. Alencar ◽  
Sergio M. Q. Lima ◽  
Fúlvio A. M. Freire
Keyword(s):  
Body Shape ◽  
Gonadal Development ◽  
Freshwater Prawn ◽  
Body Structure ◽  
Geographic Isolation ◽  
Shape Variation ◽  
Geographical Isolation ◽  
Geometric Morphometric ◽  
Sexual Shape Dimorphism ◽  
Three Body

The present study aims to show the intra- and inter-basin body-shape variations of the freshwater prawn Macrobrachium jelskii (Miers, 1877) in Brazilian Neotropical semiarid basins, quantifying relations to address if its occurrence is old and natural or recent and artificial (anthropic). We used a geometric-morphometric tool to explore patterns of shape variation of the cephalothorax, abdomen and cheliped regarding eco-evolutionary traces (sexual dimorphism, hydrodynamism and geographical isolation) among the drainages. The sexual shape dimorphism was observed in cephalothorax and abdomen of females, which presented more horizontally stretched than in males, possibly favouring gonadal development, vitellogenesis and egg attachment. No apparent hydrodynamic trend was observed in the morpho-space. Moreover, no consensus was shown in the morpho-space about the geographic isolation in semiarid basins regarding the three body-structure planes. However, the abdominal plane indicates a low population/basin structure, which can be an indirect reflection of variations of vitellogenesis in eggs modulated by environmental factors. Furthermore, morphometric variations show low phenotypic plasticity, which is supported by the literature, indicating a scenario of non-natural distribution.

scholarly journals Male sterility significantly elevates shape variation and fluctuating asymmetry of zygomorphic corolla in gynodioecious Glechoma hederacea L. (Lamiaceae)

AoB Plants ◽  
2021 ◽  
Author(s):  
Jiri Neustupa ◽  
Katerina Woodard
Keyword(s):  
Fluctuating Asymmetry ◽  
Bilateral Symmetry ◽  
Size Difference ◽  
Shape Variation ◽  
Male Sterile ◽  
Geometric Morphometric ◽  
Morphometric Analyses ◽  
Developmental Consequence ◽  
Selection For ◽  
Glechoma Hederacea

Abstract Female flowers of gynodioecious plants usually have smaller corollas than bisexual flowers. This difference is explained as a developmental consequence of stamen abortion and as a result of stronger selection for larger corolla size in hermaphroditic flowers that solely ensure male function within populations. This study evaluated whether the size difference of zygomorphic corollas in a widely distributed gynodioecious herb Glechoma hederacea L. is accompanied by variation in shape and bilateral fluctuating asymmetry of sexually differentiated flowers. Geometric morphometric analyses of bilateral symmetry in the shapes of corolla lower lips showed that male-sterile flowers were significantly more plastic and asymmetric, implying that they may be subjected to weaker stabilising selection for corolla shape in comparison to hermaphrodites. These results illustrated that sexual differentiation may be an important factor contributing to bilateral fluctuating asymmetry in the shape of zygomorphic flowers.

Ontogeny and geographic variation of a new species of the corynexochine trilobite Zacanthopsis (Dyeran, Cambrian)

2009 ◽  
Vol 83 (4) ◽  
pp. 524-547 ◽  
Author(s):  
Melanie J. Hopkins ◽  
Mark Webster
Keyword(s):  
Geographic Variation ◽  
Species Delimitation ◽  
Pairwise Comparison ◽  
Species Level ◽  
Shape Variation ◽  
Geometric Morphometric ◽  
East Central ◽  
Morphometric Methods ◽  
Cambrian Trilobite ◽  
A New Species

Assessment of ontogenetic and geographic variation can have substantial influence on species delimitation and thereby on perceived patterns of species-level morphological variation and diversity in space and time. Here we describe the ontogeny and intraspecific variation of the early Cambrian trilobite, Zacanthopsis palmeri n. sp., based on silicified material from east-central Nevada, USA. Zacanthopsis palmeri is the oldest documented Cambrian corynexochine to shift from possessing a fused rostal-hypostomal plate to a functional hypostomal suture in mature specimens during ontogeny. Six geographically distinct samples of mature Z. palmeri from a single silicified limestone bed traceable over tens of kilometers in east-central Nevada permit exploration of geographic variation within this species using geometric morphometric methods. No one sample encompasses all of the shape variation expressed by Z. palmeri and several geographically segregated samples show some degree of morphological separation in pairwise comparison. Nonetheless, these samples are not qualitatively or quantitatively different from one another when all samples are taken into account. The degree of variation within Z. palmeri is similar in magnitude to the differences between other species in the genus known from much less material.

Body shape evolution of Chromis and Azurina species (Percifomes, Pomacentridae) of the eastern Pacific

2013 ◽  
Vol 63 (2) ◽  
pp. 217-232 ◽  
Author(s):  
Rosalía Aguilar-Medrano
Keyword(s):  
Body Shape ◽  
Phylogenetic Signal ◽  
Molecular Data ◽  
The Body ◽  
Eastern Pacific ◽  
Morphological Pattern ◽  
Geometric Morphometric ◽  
Morphometric Variation ◽  
Size And Shape ◽  
Morphometric Analyses

Chromis is a circumglobal tropical and temperate genus with over 84 species of damselfishes. Studies based in osteological and molecular data have cited the relationship between Azurina and Chromis in the eastern Pacific. The main objectives of the study are: (1) to characterize size and shape in all Chromis and Azurina species of the eastern Pacific, (2) explore the phylogenetic signal of external morphology, and (3) present a hypothesis of the diversification process of this group. According to the results, there is no significant relationship between size and shape. The variation in body shape among all species is related to the height of the trunk, position of the snout and eye, and length of the caudal peduncle. The main morphologic variation between Azurina and Chromis is the degree of elongation of the body. Both Azurina species are closely related to C. punctipinnis and C. atrilobata. The morphological pattern of Azurina integrated it into Chromis. The phylogenetic pattern found by geometric morphometric analyses presented a high similarity with previous results based on molecular data. Phylogeny recovered two main clades, slender-bodied and deep-bodied species. This pattern of morphometric variation is closely related to exploitation of two different reef environments.

scholarly journals A quantitative approach to determine the taxonomic identity and ontogeny of the pycnodontiform fishPycnodus(Neopterygii, Actinopterygii) from the Eocene of Bolca Lagerstätte, Italy

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e4809 ◽  
Author(s):  
John Joseph Cawley ◽  
Giuseppe Marramà ◽  
Giorgio Carnevale ◽  
Jürgen Kriwet
Keyword(s):  
Body Shape ◽  
Morphological Variability ◽  
Fish Fauna ◽  
Quantitative Approach ◽  
Meristic Characters ◽  
Geometric Morphometric ◽  
Small Juvenile ◽  
Morphometric Analyses ◽  
Multiple Species ◽  
Large Adult

BackgroundThe pycnodontiform fishPycnodusis one of the representatives of the highly diverse actinopterygian fish fauna from the early Eocene Bolca Lagerstätte, representing one of the youngest and thus last occurrences of this extinct neopterygian clade. This genus has historically been used as a wastebasket taxon in regards to poorly known pycnodontiform fossils. Authors have argued over the specific status of the Bolca LagerstättePycnodusin terms of how many species are contained within the genus with some arguing for multiple species and others suggesting lumping all Bolca specimens together into one species.MethodsHere, we use a quantitative approach performing biometric and geometric morphometric analyses on 52 specimens ofPycnodusin order to determine if the morphological variability within the sample might be related to inter- or intraspecific variation.ResultsThe analyses revealed that the variations of body shape, morphometric and meristic characters cannot be used to distinguish different morphotypes. On the contrary, our results show a remarkable link between shape and size, related to ontogeny.DiscussionDifferences in body shape of small (juvenile) and large (adult) individuals is probably related to different microhabitats occupation on the Bolca reef with juveniles sheltering within crevices on the reef and adults being more powerful swimmers that swim above the coral. Taxonomically, we suggest that the BolcaPycnodusshould be referred to strictly asPycnodus apodusas this was the name given to the holotype. Additionally, an overview of species assigned toPycnodusis given.

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