Modularity and cranial integration across ontogenetic stages in Martino’s vole, Dinaromys bogdanovi

We explored modularity and morphological integration of the ventral cranium during postnatal ontogeny in Martino’s vole (Dinaromys bogdanovi). Two closely related phylogenetic groups, originating from the Central and Southeastern part of the species range in the western Balkans, were considered. As expected, both phylogroups had similar patterns of ontogenetic changes in cranial size and shape variation, modularity and integration. At the level of within individual variation, the hypothesis that the viscerocranial and neurocranial regions are separate modules was rejected, indicating that the hypothesized modules are not developmental, but rather functional. At the level of among individual variation, the viscerocranium and the neurocranium could not be recognized as separate modules at the juvenile stage. The strength of association between the hypothesized modules becomes lower with age which finally results in a clear 2-module organization of the ventral cranium at the adult stage. On the other hand, patterns of morphological integration for the cranium as a whole, the viscerocranium and the neurocranium stay consistent across ontogenetic stages. The developmental mechanism producing integration of the cranium as a whole, as well as integration of the neurocranium, varies throughout postnatal ontogeny. In contrast, we detected the ontogenetic stability of the mechanism responsible for covariation of viscerocranial traits which could provide ongoing flexibility of the viscerocranial covariance structure for high functional demands during lifetime. Findings from our study most likely support the idea of the ‘palimpsest-like’ model of covariance structure. Moreover, similarity or dissimilarity in the patterns of within and among individual variation in different sets of analyzed traits and comparisons across ontogenetic stages demonstrate how studies on small mammals other than mice can give new insights into postnatal cranial development.

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Morphological integration during postnatal ontogeny: implications for evolutionary biology

10.1101/2021.07.13.452198 ◽

2021 ◽

Author(s):

Alex Hubbe ◽

Guilherme Garcia ◽

Harley Sebastiao ◽

Arthur Porto ◽

Fabio Andrade Machado ◽

...

Keyword(s):

Evolutionary Biology ◽

Additive Genetic Variance ◽

Structural Similarity ◽

Morphological Integration ◽

Ontogenetic Stage ◽

Postnatal Ontogeny ◽

Phenotypic Variance ◽

Skull Morphology ◽

Genetic Covariance ◽

Ontogenetic Stages

Understanding how development changes the genetic covariance of complex phenotypes is fundamental for the study of evolution. If the genetic covariance changes dramatically during postnatal ontogeny, one cannot infer confidently evolutionary responses based on the genetic covariance estimated from a single postnatal ontogenetic stage. Mammalian skull morphology is a common model system for studying the evolution of complex structures. These studies often involve estimating covariance between traits based on adult individuals. There is robust evidence that covariances changes during ontogeny. However, it is unknown whether differences in age-specific covariances can, in fact, bias evolutionary analyses made at subadult ages. To explore this issue, we sampled two marsupials from the order Didelphimorphia, and one precocial and one altricial placental at different stages of postnatal ontogeny. We calculated the phenotypic variance-covariance matrix (P-matrix) for each genus at these postnatal ontogenetic stages. Then, we compared within genus P-matrices and also P-matrices with available congeneric additive genetic variance-covariance matrices (G-matrices) using Random Skewers and the Krzanowsky projection methods. Our results show that the structural similarity between matrices is in general high (> 0.7). Our study supports that the G-matrix in therian mammals is conserved during most of the postnatal ontogeny. Thus it is feasible to study life-history changes and evolutionary responses based on the covariance estimated from a single ontogenetic stage. Our results also suggest that at least for some marsupials the G-matrix varies considerably prior to weaning, which does not invalidate our previous conclusion because specimens at this stage would experience striking differences in selective regimes than during later ontogenetic stages.

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Ontogenetic shift in diet of a large elapid snake is facilitated by allometric change in skull morphology

10.21203/rs.3.rs-853742/v1 ◽

2021 ◽

Author(s):

Matthew Brenton Patterson ◽

Ashleigh K Wolfe ◽

Patricia A Fleming ◽

Philip W Bateman ◽

Meg Martin ◽

...

Keyword(s):

Body Size ◽

Morphological Changes ◽

Full Range ◽

Stomach Contents ◽

Prey Type ◽

Postnatal Ontogeny ◽

Shape Variation ◽

Ontogenetic Changes ◽

Skull Morphology ◽

Skull Shape

Abstract As snakes are limbless, gape-limited predators, their skull is the main feeding structure involved in prey handling, manipulation and feeding. Ontogenetic changes in prey type and size are likely to be associated with distinct morphological changes in the skull during growth. We investigated ontogenetic variation in diet from stomach contents of n = 161 dugite specimens (Pseudonaja affinis, Elapidae) representing the full range of body size for the species, and skull morphology of 46 specimens (range 0.25–1.64 m snout-vent-length; SVL). We hypothesised that changes in prey type throughout postnatal ontogeny would coincide with distinct changes in skull shape. Dugites demonstrate a distinct size-related shift in diet: the smallest individuals ate autotomised reptile tails, medium-sized individuals predominantly ate small reptiles (as snakes grew larger there was an increased likelihood of feeding on reptiles head-first), and the largest individuals (> 0.8 m SVL) ate mammals and large reptiles. Morphometric analysis revealed that ~ 40% of the variation in skull shape was associated with body size (SVL). Through ontogeny, skulls changed from a smooth, bulbous cranium with relatively small trophic bones (upper and lower jaws and their attachments), to more rugous bones (as an adaption for muscle attachment) and relatively longer trophic bones that would extend gape. Individual shape variation in trophic bone dimensions was greater in larger adults and this likely reflects natural plasticity of individuals feeding on different prey sizes/types. Rather than a distinct morphological shift with diet, the ontogenetic changes were consistent, but positive allometry of individual trophic bones resulted in disproportionate growth of the skull, reflected in increased gape size and mobility of jaw bones in adults to aid the ingestion of larger prey and improve manipulation and processing ability. These results indicate that allometric scaling is an important mechanism by which snakes can change their dietary niche.

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Ontogeny in the steinmanellines (Bivalvia: Trigoniida): an intra- and interspecific appraisal using the Early Cretaceous faunas from the Neuquén Basin as a case study

Paleobiology ◽

10.1017/pab.2021.32 ◽

2021 ◽

pp. 1-23

Author(s):

Pablo S. Milla Carmona ◽

Dario G. Lazo ◽

Ignacio M. Soto

Keyword(s):

Trajectory Analysis ◽

Sedentary Lifestyle ◽

Shape Change ◽

Shell Shape ◽

Shape Variation ◽

Ontogenetic Changes ◽

Ontogenetic Trajectories ◽

Higher Genus ◽

Gradual Decay

Abstract Despite the paleontological relevance and paleobiological interest of trigoniid bivalves, our knowledge of their ontogeny—an aspect of crucial evolutionary importance—remains limited. Here, we assess the intra- and interspecific ontogenetic variations exhibited by the genus Steinmanella Crickmay (Myophorellidae: Steinmanellinae) during the early Valanginian–late Hauterivian of Argentina and explore some of their implications. The (ontogenetic) allometric trajectories of seven species recognized for this interval were estimated from longitudinal data using 3D geometric morphometrics, segmented regressions, and model selection tools, and then compared using trajectory analysis and allometric spaces. Our results show that within-species shell shape variation describes biphasic ontogenetic trajectories, decoupled from ontogenetic changes shown by sculpture, with a gradual decay in magnitude as ontogeny progresses. The modes of change characterizing each phase (crescentic growth and anteroposterior elongation, respectively) are conserved across species, thus representing a feature of Steinmanella ontogeny; its evolutionary origin is inferred to be a consequence of the rate modification and allometric repatterning of the ancestral ontogeny. Among species, trajectories are more variable during early ontogenetic stages, becoming increasingly conservative at later stages. Trajectories’ general orientation allows recognition of two stratigraphically consecutive groups of species, hinting at a potentially higher genus-level diversity in the studied interval. In terms of functional morphology, juveniles had a morphology more suited for active burrowing than adults, whose features are associated with a sedentary lifestyle. The characteristic disparity of trigoniids could be related to the existence of an ontogenetic period of greater shell malleability betrayed by the presence of crescentic shape change.

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Unravelling the hybrid vigor in domestic equids: the effect of hybridization on bone shape variation and covariation

BMC Evolutionary Biology ◽

10.1186/s12862-019-1520-2 ◽

2019 ◽

Vol 19 (1) ◽

Cited By ~ 4

Author(s):

Pauline Hanot ◽

Anthony Herrel ◽

Claude Guintard ◽

Raphaël Cornette

Keyword(s):

First Generation ◽

Shape Change ◽

Morphological Integration ◽

Hybrid Vigor ◽

F1 Hybrids ◽

Shape Variation ◽

Locomotor System ◽

Domestic Horses ◽

Functional Mechanisms ◽

Underlying Processes

Abstract Background Hybridization has been widely practiced in plant and animal breeding as a means to enhance the quality and fitness of the organisms. In domestic equids, this hybrid vigor takes the form of improved physical and physiological characteristics, notably for strength or endurance. Because the offspring of horse and donkey is generally sterile, this widely recognized vigor is expressed in the first generation (F1). However, in the absence of recombination between the two parental genomes, F1 hybrids can be expected to be phenotypically intermediate between their parents which could potentially restrict the possibilities of an increase in overall fitness. In this study, we examine the morphology of the main limb bones of domestic horses, donkeys and their hybrids to investigate the phenotypic impact of hybridization on the locomotor system. We explore bone shape variation and covariation to gain insights into the morphological and functional expressions of the hybrid vigor commonly described in domestic equids. Results Our data reveal the occurrence of transgressive effects on several bones in the F1 generation. The patterns of morphological integration further demonstrate that the developmental processes producing covariation are not disrupted by hybridization, contrary to functional ones. Conclusions These results suggest that an increase in overall fitness could be related to more flexibility in shape change in hybrids, except for the main forelimb long bones of which the morphology is strongly driven by muscle interactions. More broadly, this study illustrates the interest of investigating not only bone shape variation but also underlying processes, in order to contribute to better understanding how developmental and functional mechanisms are affected by hybridization.

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Individual variation of the masticatory system dominates 3D skull shape in the herbivory-adapted marsupial wombats

10.1101/692632 ◽

2019 ◽

Author(s):

Vera Weisbecker ◽

Thomas Guillerme ◽

Cruise Speck ◽

Emma Sherratt ◽

Hyab Mehari Abraha ◽

...

Keyword(s):

Individual Variation ◽

Principal Component ◽

Individual Variability ◽

Shape Variation ◽

Mandibular Ramus ◽

Geometric Morphometric ◽

Skull Shape ◽

Marsupial Species ◽

Masticatory System ◽

The Individual

AbstractBackgroundWithin-species skull shape variation of marsupial mammals is widely considered low and strongly size-dependent (allometric), possibly due to developmental constraints arising from the altricial birth of marsupials. However, species whose skulls are impacted by strong muscular stresses – particularly those produced through mastication of tough food items – may not display such intrinsic patterns very clearly because of the known plastic response of bone to muscle activity of the individual. In such cases, shape variation should not be dominated by allometry; ordination of shape in a geometric morphometric context through principal component analysis (PCA) should reveal main variation in areas under masticatory stress (incisor region/zygomatic arches/mandibular ramus); but this main variation should emerge from high individual variability and thus have low eigenvalues.ResultsWe assessed the evidence for high individual variation through 3D geometric morphometric shape analysis of crania and mandibles of thre species of grazing-specialized wombats, whose diet of tough grasses puts considerable strain on their masticatory system. As expected, we found little allometry and low Principal Component 1 (PC1) eigenvalues within crania and mandibles of all three species. Also as expected, the main variation was in the muzzle, zygomatic arches, and masticatory muscle attachments of the mandibular ramus. We then implemented a new test to ask if the landmark variation reflected on PC1 was reflected in individuals with opposite PC1 scores and with opposite shapes in Procrustes space. This showed that correspondence between individual and ordinated shape variation was limited, indicating high levels of individual variability in the masticatory apparatus.DiscussionOur results are inconsistent with hypotheses that skull shape variation within marsupial species reflects a constraint pattern. Rather, they support suggestions that individual plasticity can be an important determinant of within-species shape variation in marsupials (and possibly other mammals) with high masticatory stresses, making it difficult to understand the degree to which intrinsic constraint act on shape variation at the within-species level. We conclude that studies that link micro- and macroevolutionary patterns of shape variation might benefit from a focus on species with low-impact mastication, such as carnivorous or frugivorous species.

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Inferring Developmental Modularity from Morphological Integration: Analysis of Individual Variation and Asymmetry in Bumblebee Wings

The American Naturalist ◽

10.1086/317002 ◽

2001 ◽

Vol 157 (1) ◽

pp. 11-23 ◽

Cited By ~ 162

Author(s):

Christian Peter Klingenberg ◽

Alexander V. Badyaev ◽

Susanna M. Sowry ◽

Nathan J. Beckwith

Keyword(s):

Individual Variation ◽

Morphological Integration ◽

Integration Analysis

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A geometric morphometric analysis of hominin upper premolars. Shape variation and morphological integration

Journal of Human Evolution ◽

10.1016/j.jhevol.2011.09.004 ◽

2011 ◽

Vol 61 (6) ◽

pp. 688-702 ◽

Cited By ~ 47

Author(s):

Aida Gómez-Robles ◽

María Martinón-Torres ◽

José María Bermúdez de Castro ◽

Leyre Prado-Simón ◽

Juan Luis Arsuaga

Keyword(s):

Morphometric Analysis ◽

Morphological Integration ◽

Shape Variation ◽

Geometric Morphometric ◽

Geometric Morphometric Analysis

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Geometric morphometrics of nested symmetries: Hierarchical INTER- AND INTRA-INDIVIDUAL VARIATION IN BIOLOGICAL SHAPES

10.1101/306712 ◽

2018 ◽

Cited By ~ 1

Author(s):

Yoland Savriama ◽

Sylvain Gerber

Keyword(s):

Individual Variation ◽

Biological Object ◽

Sea Urchins ◽

Rotational Symmetry ◽

Large Body ◽

Bilateral Symmetry ◽

Morphological Integration ◽

Full Symmetry ◽

Masticatory Apparatus ◽

Complex Organ

AbstractSymmetry is a pervasive feature of organismal shape and the focus of a large body of research in Biology. Here, we consider complex patterns of symmetry where a phenotype exhibits a hierarchically structured combination of symmetries. We extend the Procrustes ANOVA for the analysis of nested symmetries and the decomposition of the overall morphological variation into components of symmetry (among-individual variation) and asymmetry (directional and fluctuating asymmetry). We illustrate its use with the Aristotle’s lantern, the masticatory apparatus of ‘regular’ sea urchins, a complex organ displaying bilateral symmetry nested within five-fold rotational symmetry. Our results highlight the importance of characterising the full symmetry of a structure with nested symmetries. Higher order rotational symmetry appears strongly constrained and developmentally stable compared to lower level bilateral symmetry. This contrast between higher and lower levels of asymmetry is discussed in relation to the spatial pattern of the lantern morphogenesis. This extended framework is applicable to any biological object exhibiting nested symmetries, regardless of their type (e.g., bilateral, rotational, translational). Such cases are extremely widespread in animals and plants, from arthropod segmentation to angiosperm inflorescence and corolla shape. The method therefore widens the research scope on developmental instability, canalization, developmental modularity and morphological integration.

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Anhanguera taxonomy revisited: is our understanding of Santana Group pterosaur diversity biased by poor biological and stratigraphic control?

PeerJ ◽

10.7717/peerj.3285 ◽

2017 ◽

Vol 5 ◽

pp. e3285 ◽

Cited By ~ 19

Author(s):

Felipe L. Pinheiro ◽

Taissa Rodrigues

Keyword(s):

Temporal Variations ◽

Northeastern Brazil ◽

Shape Variation ◽

Ontogenetic Changes ◽

Geometric Morphometric ◽

Considerable Difficulty ◽

Faunal Turnover ◽

Definition Of ◽

Almost All ◽

New Diagnosis

Background Anhanguerids comprise an important clade of pterosaurs, mostly known from dozens of three-dimensionally preserved specimens recovered from the Lower Cretaceous Romualdo Formation (northeastern Brazil). They are remarkably diverse in this sedimentary unit, with eight named species, six of them belonging to the genus Anhanguera. However, such diversity is likely overestimated, as these species have been historically diagnosed based on subtle differences, mainly based on the shape and position of the cranial crest. In spite of that, recently discovered pterosaur taxa represented by large numbers of individuals, including juveniles and adults, as well as presumed males and females, have crests of sizes and shapes that are either ontogenetically variable or sexually dimorphic. Methods We describe in detail the skull of one of the most complete specimens referred to Anhanguera, AMNH 22555, and use it as a case study to review the diversity of anhanguerids from the Romualdo Formation. In order to accomplish that, a geometric morphometric analysis was performed to assess size-dependent characters with respect to the premaxillary crest in the 12 most complete skulls bearing crests that are referred in, or related to, this clade, almost all of them analyzed first hand. Results Geometric morphometric regression of shape on centroid size was highly statistically significant (p = 0.0091) and showed that allometry accounts for 25.7% of total shape variation between skulls of different centroid sizes. Premaxillary crests are both taller and anteroposteriorly longer in larger skulls, a feature consistent with ontogenetic growth. A new diagnosis is proposed for Anhanguera, including traits that are nowadays known to be widespread within the genus, as well as ontogenetic changes. AMNH 22555 cannot be referred to “Anhanguera santanae” and, in fact, “Anhanguera santanae”, “Anhanguera araripensis”, and “Anhanguera robustus” are here considered nomina dubia. Discussion Historically, minor differences in crest morphology have been used in the definition of new anhanguerid species. Nowadays, this practice resulted in a considerable difficulty in referring well-preserved skulls into known taxa. When several specimens are analyzed, morphologies previously believed to be disparate are, in fact, separated by a continuum, and are thus better explained as individual or temporal variations. Stratigraphically controlled excavations on the Romualdo Formation have showed evidence for faunal turnover regarding fish communities. It is thus possible that some of the pterosaurs from this unit were not coeval, and might even represent anagenetic morphotypes. Unfortunately, amateur collecting of Romualdo Formation fossils, aimed especially at commerce, resulted in the lack of stratigraphic data of virtually all its pterosaurs and precludes testing of these further hypotheses.

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GENETIC ANALYSIS OF SIZE-SCALING PATTERNS IN THE MOUSE MANDIBLE

Genetics ◽

10.1093/genetics/111.3.579 ◽

1985 ◽

Vol 111 (3) ◽

pp. 579-595

Author(s):

William R Atchley ◽

A Alison Plummer ◽

Bruce Riska

Keyword(s):

Genetic Variance ◽

Adult Mouse ◽

Genetic Correlations ◽

Covariance Structure ◽

Ontogenetic Changes ◽

Skeletal Morphology ◽

Quantitative Genetic ◽

Functional Aspects ◽

The Impact ◽

The Relationship

ABSTRACT The relationship between multidimensional form of the adult mouse mandible and body size is examined from an ontogenetic perspective. The origin and ontogeny of phenotypic correlations are described in terms of genetic and environmental covariance patterns between adult skeletal morphology and growth in body weight. Different ontogenetic patterns are observed in the genetic correlations, and these can be related to the developmental as well as the functional aspects of mandibular form. The quantitative genetic aspects of craniomandibular growth and morphogenesis are explored, together with an examination of the impact of ontogenetic changes in the genetic variance-covariance structure on morphogenetic integration and evolution by selection.

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