Morphological Variation Research Articles

Chasing the Rainbow: Decoupled phenotypic and genotypic evolution in New Guinea’s rainbow skinks (Squamata: Scincidae)

With the advent of molecular data, the discovery of cryptic species has become commonplace. New Guinea, a region of high vertebrate biodiversity and complex geological history, has been found to contain immense numbers of cryptic skink species. We present the first molecular phylogenetic analysis of Carlia Gray, 1845, and its sister genus Lygisaurus de Vis, 1884, across mainland New Guinea and the Solomon Islands. We find rainbow skinks exhibit significant genetic divergence with minimal morphological variation and our data suggest the existence of many undescribed species. Due to the morphologically cryptic nature of rainbow skinks, we demonstrate the efficacy of the COI gene as a “barcode” for difficult species determinations. Divergence time and biogeographic analyses support four separate dispersal events from Australia to New Guinea for rainbow skinks from ~10–5 mya, with most groups arriving first in the East Papua Composite Terrane (EPCT) and dispersing from there to other terranes and islands. Exceptions to this pattern were observed in Lygisaurus, which dispersed first to the West Papuan portion of the Craton ~8.4mya, and the island clade of the Carlia fusca group, which dispersed to the Vogelkop peninsula ~4.7mya and from there to many islands.

Anatomical and morphological variations in the dorsal root ganglion: Technical implications for chronic pain treatment with neuromodulation-A systematic review.

In the last 20 years, we have seen the flourishing of multiple treatments targeting the dorsal root ganglion (DRG) for pain. However, there is concern regarding the variation in the location of the DRG, which could influence the long-term clinical outcomes. The aim of this work was to determine the exact position of the DRG in the spine and propose a pre-surgical planning. A systematic search was conducted following the principles recommended by PRISMA. Search terms "ganglia," "DRG," "dorsal root ganglia, anatomy," "radiological," "neuromodulation," "dorsal root ganglion stimulation" (PubMed, Scopus, Medline, Web of Science, and Embase) were identified 177 articles and subjected to the selection criteria (inclusion/exclusion) based on the independent review of the abstracts. Eighteen articles were selected (seven anatomical dissections on cadavers, five radiological studies, and six narrative reviews). Percutaneous procedure targeting the DRG for the treatment of chronic pain requires preoperative planning independent to the study of the etiology of pain. The DRG should be typified using magnetic resonance imaging. We propose a preoperative evaluation scale based on four specific items: A-position in the vertebral canal, B-position of the DRG within the foramen, C-number of ganglia in the root, and D-ratio (proportion) of foramen/DRG. Percutaneous treatments for chronic pain directed at the DRG are effective. Clinical outcomes depend of good preoperative planning that allows for optimizing its effects. We propose a DRG morphology evaluation scale useful for the planning process prior to any treatment directed at the ganglion.

Mechanical modeling of biofilm morphology variation induced by changes in environments and internal stress

Mechanical modeling of biofilm morphology variation induced by changes in environments and internal stress

Morphological changes to peripheral joints supporting thumb trapezial metacarpal osteoarthritis.

The present study aims to determine if morphological differences of the scaphoid, trapezoid, and second metacarpal are associated with thumb osteoarthritis by comparing three-dimensional bone models of healthy controls and osteoarthritis patients. Fifty-eight patients with moderate to severe thumb osteoarthritis (modified Eaton≥II) and 35 healthy controls from a larger completed investigation were examined. To quantify morphological variations, a statistical shape model was created that classified binary with respect to the Eaton grading system: non-osteoarthritis or moderate/severe osteoarthritis (II-IV). Three-dimensional surface models based on computed tomography images from the scaphoid, trapezoid, and second metacarpal were used to "train" the statistical shape model and yielded features that best explain variation within the three bones: the principal components These principal components were tested for significant differences between patient and control group. Additionally, a statistical shape model entailing all three bones was created. For the second metacarpal, only a single principal component was significantly associated with osteoarthritis (p=0.035). The combined model utilizing all three bones, however, showed that with using one principal component of each of the bones, we could classify a sample as moderate/severe trapeziometacarpal osteoarthritis with an accuracy of 0.77. No individual shape components of the scaphoid or trapezoid significantly correlated to osteoarthritis. This study affirms that basilar thumb osteoarthritis is not limited to the trapeziometacarpal joint. Future studies investigating surrounding bones and joints as contributors to disease occurrence or progression will provide a more holistic insight into the prevention, diagnostic, and treatment of thumb osteoarthritis.

Morphological Analysis of Prefixes in the Makasae Language

This study examines the morphological processes in the Makasae language, focusing on the use of prefixes ‘Au’- and ‘Tuli’- to form adjectives and verbs. Makasae, a language spoken primarily in East Timor, belongs to the Trans-New Guinea language family and features a rich system of affixation. The research employs a qualitative descriptive approach to analyze data collected through elicitation tasks and sentence construction with native speakers. The study examines how the prefix ‘Au’- attaches to various root words to create descriptive adjectives, while ‘Tuli’- combines with verb roots to form dynamic and forceful action verbs. The findings highlight the productivity and regularity of these prefixes in shaping Makasae’s verbal and adjectival morphology. ‘Au’- is found to serve as an adjectivizing tool, whereas ‘Tuli’- contributes to the formation of action-oriented verbs with a sense of intensity or aggression. The study contributes to a deeper understanding of Makasae’s affixation system and its role in the broader context of Trans-New Guinea linguistics. Further research is recommended to explore additional morphological processes and regional variations in the use of these affixes.

Museomic analyses clarify species diversity in the icefish genus Channichthys

The rapid diversification of notothenioid fishes in Antarctic waters is a prime example of the process of adaptive radiation. Within around 10 million years, Antarctic notothenioids have diversified into over 100 species with a broad range of lifestyles and ecological adaptations. However, the exact number of species within this radiation has long been unclear. Particularly challenging is the taxonomy of the genus Channichthys, for which between one and nine species have been recognized by different authors. The putative species of this genus are known from a limited number of specimens, of which most were sampled decades ago. Here, we investigated the mitochondrial genomes of museum specimens representing the four species Unicorn Icefish (C. rhinoceratus), Red Icefish (C. rugosus), Sailfish Pike (C. velifer), and Charcoal Icefish (C. panticapaei), complemented by morphological analyses. All analyzed specimens were collected in the 1960s and 1970s and fixed in formaldehyde, and their DNA has been heavily degraded. Applying ancient-DNA protocols for DNA extraction and single-stranded library preparation, we were able to obtain sufficient endogenous DNA to reconstruct the mitochondrial genomes of one specimen per species. These mitochondrial genome sequences were nearly identical for the three specimens assigned to Unicorn Icefish, Red Icefish, and Sailfish Pike, while greater divergence was observed for the Charcoal Icefish specimens. We discuss possible explanations of the contrast between these molecular results and the recognizable morphological variation found among the four species, and recommend that at least the Charcoal Icefish be included in the list of valid notothenioid species.

A statistical shape and density model can accurately predict bone morphology and regional femoral bone mineral density variation in children.

Finite element analysis (FEA) is a widely used tool to predict bone biomechanics in orthopaedics for prevention, treatment, and implant design. Subject-specific FEA models are more accurate than generic adult-scaled models, especially for a paediatric population, due to significant differences in bone geometry and bone mineral density. However, creating these models can be time-consuming, costly and requires medical imaging. To address these limitations, population-based models have been successful in characterizing bone shape and density variation in adults. However, children are not small adults and need their own population-based model to generate accurate and accessible musculoskeletal geometry and bone mineral density in a paediatric population. Therefore, this study aimed to create a biomechanical research tool to predict the personalized shape and density of the paediatric femur using a statistical shape and density model for a population of children aged from 4 to 18 years old. Femur morphology and bone mineral density were extracted from 330 CT scans of children. Variations in shape and density were captured using Principal Component Analysis (PCA). Principal components were correlated to demographic and linear bone measurements to create a predictive statistical shape-density model, which was used to predict femoral shape and density. A leave-one-out analysis showed that the shape-density model can predict the femur geometry with a root mean square error (RMSE) of 1.78 ± 0.46 mm and the bone mineral density with a normalized RMSE ranging from 8.9 % to 13.5 % across various femoral regions. These results underscore the model's potential to reflect real-world physiological variations in the paediatric femur. This statistical shape and density model has the potential for clinical application in rapidly generating personalized computational models using partial or no medical imaging data.

Enhancing furcation involvement classification on panoramic radiographs with vision transformers

BackgroundThe severity of furcation involvement (FI) directly affected tooth prognosis and influenced treatment approaches. However, assessing, diagnosing, and treating molars with FI was complicated by anatomical and morphological variations. Cone-beam computed tomography (CBCT) enhanced diagnostic accuracy for detecting FI and measuring furcation defects. Despite its advantages, the high cost and radiation dose associated with CBCT equipment limited its widespread use. The aim of this study was to evaluate the performance of the Vision Transformer (ViT) in comparison with several commonly used traditional deep learning (DL) models for classifying molars with or without FI on panoramic radiographs.MethodsA total of 1,568 tooth images obtained from 506 panoramic radiographs were used to construct the database and evaluate the models. This study developed and assessed a ViT model for classifying FI from panoramic radiographs, and compared its performance with traditional models, including Multi-Layer Perceptron (MLP), Visual Geometry Group (VGG)Net, and GoogLeNet.ResultsAmong the evaluated models, the ViT model outperformed all others, achieving the highest precision (0.98), recall (0.92), and F1 score (0.95), along with the lowest cross-entropy loss (0.27) and the highest accuracy (92%). ViT also recorded the highest area under the curve (AUC) (98%), outperforming the other models with statistically significant differences (p < 0.05), confirming its enhanced classification capability. The gradient-weighted class activation mapping (Grad-CAM) analysis on the ViT model revealed the key areas of the images that the model focused on during predictions.ConclusionDL algorithms can automatically classify FI using readily accessible panoramic images. These findings demonstrate that ViT outperforms the tested traditional models, highlighting the potential of transformer-based approaches to significantly advance image classification. This approach is also expected to reduce both the radiation dose and the financial burden on patients while simultaneously improving diagnostic precision.

Reevaluating the infraspecific taxa of Maesa rugosa C.B. Clarke (Primulaceae): Taxonomic reassessment and typification update

Maesa rugosa C.B. Clarke is a tropical shrub belonging to the family Primulaceae. Despite its prevalent distribution and morphological variation, the infraspecific taxonomy of M. rugosa remains unclear. The present study reevaluates the infraspecific classification of M. rugosa based on a comprehensive analysis of the morphological characters. Our study results in reorganizing three infraspecific taxa including one new variety and one new combination. We also provide an update on the typification of two names M. rugosa C.B. Clarke and M. rugosa var. griffithii C.B. Clarke following Articles 9.2 and 9.17 of the ICN code.

Unveiling pterion variability: a meta-analytic approach to enhance neurosurgical precision

PurposeThis meta-analytical systematic review aims at investigating the variability of the pterion, focusing on its morphological types and precise distances from various bony landmarks. Additionally, the neurosurgical significance of this critical cranial landmark is examined in depth.MethodsThe systematic review was conducted following PRISMA 2020 and Evidence-based Anatomy Workgroup guidelines for anatomical studies. The risk of bias was assessed using the Anatomical Quality Assurance Tool (AQUA). The meta-analysis was performed using R programming software and RStudio, employing the “meta” and “metafor” packages.ResultsA total of 79 studies were included, encompassing 18,694 skull sides. The sphenoparietal type was identified as the most prevalent pterion variant, with a pooled prevalence of 78.54%. The epipteric type followed at 8.41%, while the frontotemporal (5.74%) and stellate (4.26%) types were the rarest. Significant differences in the prevalence of the epipteric, frontotemporal, and stellate types were observed across different nationalities. However, sex, side, and study type did not significantly influence pterion morphological variation. The study also extracted and calculated the distances between the pterion and key anatomical landmarks, including the midpoint of the zygomatic arch, the frontozygomatic suture, the mastoid process, and the external acoustic meatus.ConclusionThis study offers critical anatomical insights by accurately mapping the pterion’s location relative to essential cranial landmarks. These findings are vital for neurosurgical planning, particularly for procedures involving the anterior and middle cranial fossae. The detailed anatomical data provided can enhance the precision and safety of neurosurgical interventions, ultimately improving patient outcomes.

3-D burrow morphology of Chondrites targionii (Brongniart, 1828) from an Upper Jurassic firmground of Southern Germany

Chondrites is a common ichnogenus and typified by Chondrites targionii, with peak appearance in Upper Cretaceous deep-marine deposits. These burrows were commonly developed in soft substrate, which suffered from subsequent compaction that obliterated their three-dimensional (3-D) morphology and characteristics aiding the producers’ interpretation, although deep-tier firmground burrows occur too. Micro-CT-scanning of a sample from an Upper Jurassic (Kimmeridgian) carbonate firmground (southern Germany) allowed the reconstruction of the 3-D morphology of C. targionii for the first time. For comparison with the sample, all six C. targionii syntypes were morphometrically analysed. Within the sample, two-dimensional (2-D) and 3-D morphometric analyses identified 48 burrow parts containing 221 branches (up to the third branch order), another 29 tunnels with obviously very low branch width, one crossing tunnel and another tunnel with scale-leaf-shaped structures on its outer surface. Eleven identified burrow portions are likely parts of three larger burrow systems. With intermediate effect size, statistically compared branch widths revealed significantly decreasing widths from unbranched tunnels over root branches to their side branches, which, along with the scale-leaf-shaped structures, may indicate a vermiform tracemaker. The results of the 3-D analyses revealed the ratio of tunnel width to burrow system width as useful discriminator of C. targionii covering a larger portion of its morphological variation.

Aberrations in Root Canal Morphology: A Case Series

A clear understanding of the anatomy and morphology of root canals is an essential pre-requisite for carrying out a successful endodontic treatment. One of the major causes of failure of root canal treatment is complexity of the anatomy of pulp canal space. Variations in root canal morphology presents constant challenges for the clinician. With the advent of magnification and other diagnostic and treatment adjuvants, searching for and treating root canals has become easier and more predictable. This article presents case series emphasizing on the significance of thorough knowledge regarding root canal morphology and the associated anatomical aberrations. Keywords: Root canal aberrations; Angulated IOPAR’s; Mandibular molar; Mandibular Central Incisor; Mandibular Canine.

8000 Years of morphometric evolution of sheep, goat and pig in the northwestern Mediterranean basin

Understanding how domestic mammal species evolved through time provides insight into the artificial and natural selection processes that have shaped the diversity of domestic animals. The focus of this article is the morphometric evolution of sheep, goats and suids in the Northwestern Mediterranean Basin over the last 8000 years, employing a 2D geometric morphometrics protocol applied to the third lower molars. Using a comprehensive dataset comprising 2798 archaeological specimens from 176 sites in Southern France and Spanish Catalonia, along with 1303 modern specimens, we aim to identify and contrast the environmental and anthropic factors influencing species evolution linked to past husbandry practices. Each of these three taxa follows its own evolutionary trajectory, exhibiting variations over time and across different regions. Notably, reduction in the centroid size of sheep molars between the Neolithic and the early Iron Age could potentially be associated with an increased demand for meat and/or shifts in male-to-female ratios. A clear geographical structuring of caprines between the Neolithic and Antiquity is observed, likely influenced by a combination of factors including artificial selection, environmental changes and socio-economic dynamics, as corroborated by previous studies. Moreover, a reduction in molar size during the Middle Ages is observed across all three species, possibly linked to extensive agropastoral practices. Furthermore, divergent processes of breed improvement and standardization are identified in pigs and caprines. This study highlights the complex nature of morphological variations in domestic species, emphasising the multifactorial influences involved. It underscores the importance of interdisciplinary approaches in understanding the factors contributing to morphological transformations over time.

Preliminary insight of pollen morphology of the Amazonian members of subtribe Columneineae (Gesneriaceae): details of morphological variation and pollen types

Preliminary insight of pollen morphology of the Amazonian members of subtribe Columneineae (Gesneriaceae): details of morphological variation and pollen types

Winter Activity and Dormancy of Snails: Freezing and Food Shortage Avoidance Strategy Facing Snow-Cover Shortage

Cold tolerance is a key factor shaping the survival and geographic distribution of terrestrial snails, especially in regions with harsh winters. Understanding how these organisms cope with freezing temperatures is crucial for predicting their responses to changing climates. This study focused on two microsnail species, Vertigo antivertigo and V. moulinsiana, to assess their winter activity, cold tolerance strategies, and whether their body size varies with latitude. Activity patterns were observed under controlled temperatures (0 °C, 2 °C, and 5 °C), while supercooling points (SCP) were measured to evaluate freezing avoidance. Shell morphology was analyzed across populations from various sites in Poland to explore local adaptations. The results showed that snail activity decreases as temperatures drop, with the lowest activity observed at 0 °C. Both species displayed a freezing-avoidant strategy, with V. moulinsiana having slightly higher SCP values, reflecting its adaptation to milder climates. Morphological differences in shell dimensions across sites suggest potential local adaptations to environmental conditions. These findings highlight temperature as a critical driver of activity, survival, and morphological variation in terrestrial snails. Limited winter activity may allow foraging or shelter-seeking but poses risks for overwintering. As climate change leads to snow-free winters, these species may face significant challenges in maintaining their populations and distributions.

Morphological diversity variation of seed traits among 587 germplasm resources of Medicago Genus and 32 germplasm resources of Trigonella Genus

Germplasm resources within the Medicago genus are highly regarded for their value as forage crops and their critical roles in nitrogen cycling, ecosystem restoration, and soil structure improvement. Therefore, understanding the diversity of seed morphology in this genus is essential for advancing its development and utilization. This study analyzed seed samples from 587 germplasm accessions representing 77 species within Medicago genus, as well as 32 accessions from 21 species within the closely related genus Trigonella. A statistical analysis was conducted on twelve traits, including seven quantitative traits-straight length (SL), straight width (SW), width-to-length ratio (WL), perimeter (PE), radicle length (RL), hilum length (HL), and 100-seed weight (SY)-and five qualitative traits, including seed coat condition, radicle characteristics, seed size, shape, and color. The results revealed that: (1) there was significant diversity (P < 0.05) in SL, SW, WL, PE, RL, HL, and SY across Medicago species; (2) principal component analysis of the 587 Medicago accessions identified SL, SW, PE, HL, RL, and SY as the primary contributors to morphological diversity; and (3) high-resolution images of seeds from various accessions were captured for future research. This study provides a solid foundation for the establishment of seed banks and the enhancement of germplasm resources through the systematic analysis of these morphological traits.

Tracking evolutionary changes within Allophaiomys, Terricola and Microtus voles revealed by a landmark point-based geometric morphometric study on molars from Hungary

ABSTRACT In the present work, a geometric morphologic study was carried out to compare the lower first molars of species belonging to the genera Allophaiomys, Terricola and Microtus and to explore the morphological variation within species. The examined teeth were recovered from nine Early and Middle Pleistocene sites, but recent material was also used in the study. We analysed the teeth of 733 Allophaiomys spp. 855 Terricola arvalidens, 339 Terricola hintoni and 625 recent Terricola subterraneus. Morphology and linear morphometric data of teeth were compared using canonical variate analysis and landmark analysis. The resulting morphological series reflect the phylogenetic relationships between species. We also tested the morphological changes observed in the fossil material with the separation times calculated from recent phylogenetic studies. Our results suggest that most phylogenetic changes can be traced by morphological analysis of this tooth. While the emergence of species belonging to the genera Terricola and Microtus is broadly consistent with the phylogenetic data, early colonisation of the genus Agricola was not morphologically detectable. The study of the genus Allophaiomys has revealed a palaeoecological difference between northern and southern Hungary during the mid-Pleistocene transition. Southern Hungary was covered with steppe, while northern Hungary was forested at that time.

Relationship between insertions of the tibialis anterior and peroneus longus and first tarsometatarsal joint degeneration

BackgroundThe purpose of this study was to clarify the relationships of the tibialis anterior tendon (TAT) and peroneus longus tendon (PLT) with articular cartilage degeneration on the medial cuneiform and first metatarsal.MethodsWe examined 100 feet from 50 Japanese cadavers. The TAT was classified into 4 types based on attachment site area and number of fiber bundles: Type I, two fiber bundles with equal (within 20%) attachment site areas on the first metatarsal and medial cuneiform; Type II, with two fiber bundles and a larger (>20%) attachment site area on the medial cuneiform than on the first metatarsal; Type III, with two fiber bundles and a larger (>20%) attachment site area on the first metatarsal than on the medial cuneiform; and Type IV, with three fiber bundles. The PLT was classified into 2 types, following previous studies: Type I, insertion only to the base of the first metatarsal; Type II, insertion to the medial cuneiform and first metatarsal. The severity of articular cartilage degeneration was assessed in five stages using the International Cartilage Repair Society scale.ResultsNo significant difference in severity of articular cartilage degeneration was evident among types of TAT and PLT.ConclusionOur results suggested that anatomical variations in the TAT and PLT might not affect joint stability, indicating that strengthening of these muscles could potentially enhance stability regardless of morphological variations in the insertions.

How widespread is pollination by sexual deception of fungus gnats in Pterostylis (Orchidaceae)?

Abstract Pollination by sexual deception has evolved multiple times in the Orchidaceae, with most known cases involving male Hymenoptera as pollinators. The diverse Australasian orchid genus Pterostylis, characterized by elaborate trap flowers, contains some species pollinated by sexual deception of fungus gnats (Diptera). However, there is considerable variation in floral morphology, suggesting that additional pollination strategies or pollen vectors may be involved. Here, we test the hypothesis that sexual deception of male Diptera is taxonomically widespread by investigating the pollination systems across a representative subset spanning nine out of 10 sections and 18 Pterostylis species. We confirm four new cases of pollination by sexual deception of male fungus gnats (families Mycetophilidae, Keroplatidae, and Sciaridae) and accrued evidence for three further cases. Each of these orchids was pollinated by a single species of fungus gnat, with two species exploiting the same pollinator. Unexpectedly, we observed insect feeding behaviour on two species pollinated by sciarid gnats and phorid flies, respectively, with trace levels of sucrose detected where feeding was observed. Our results show that the sexual deception of male fungus gnats is likely to be the dominant mode of pollination in Pterostylis, although other poorly understood pollination strategies are also present.

Small fish, large variation: Morphological diversity of Weberian apparatus in Noturus catfishes and ecological implications.

The Weberian apparatus is a hearing specialization unique to the otophysan fishes, and an unexpected degree of morphological variation exists in species of the Noturus catfishes. Our aim in this study is to investigate relationships between morphological variations and ecology that may drive this variation. Sampling 48 specimens representing 25 species, we investigated morphological diversity and accounted for ecological variables using landmark-based 3D geometric morphometrics and x-ray-based computed tomography (CT) images. We tested five ecological variables using three landmark sets in three focused regions: the tripus, scaphium, and overall shape of the peripheral structures including the complex vertebra. We performed phylogenetic signal tests, and phylogenetic influence is not significant within Noturus in any of the three regions. Among the tested ecological variables, stream velocity and coloration (a proxy for substrate) were found to be significantly associated with the morphology of the tripus and scaphium, the first and the last ossicles of the sound transmitting chain. This eco-morphology connection may be mediated through stream velocity's dominant role in defining the soundscape of aquatic environments and substrate material properties contributing to which sounds are produced and propagated. We conclude that Noturus catfishes could be acoustically adapted to their microhabitats.