Geometric Morphometric Techniques Research Articles

Modeling the effect of brain growth on cranial bones using finite-element analysis and geometric morphometrics.

Brain expansion during ontogeny has been identified as a key factor for explaining the growth pattern of neurocranial bones. However, the dynamics of this relation are only partially understood and a detailed characterization of integrated morphological changes of the brain and the neurocranium along ontogeny is still lacking. The aim of this study was to model the effect of brain growth on cranial bones by means of finite-element analysis (FEA) and geometric morphometric techniques. First, we described the postnatal changes in brain size and shape by digitizing coordinates of 3D semilandmarks on cranial endocasts, as a proxy of brain, segmented from CT-scans of an ontogenetic sample. Then, two scenarios of brain growth were simulated: one in which brain volume increases with the same magnitude in all directions, and other that includes the information on the relative expansion of brain regions obtained from morphometric analysis. Results indicate that in the first model, in which a uniform pressure is applied, the largest displacements were localized in the sutures, especially in the anterior and posterior fontanels, as well as the metopic suture. When information of brain relative growth was introduced into the model, displacements were also concentrated in the lambda region although the values along both sides of the neurocranium (parietal and temporal bones) were larger than under the first scenario. In sum, we propose a realistic approach to the use of FEA based on morphometric data that offered different results to more simplified models.

Cranial size and shape sexual dimorphism in the Kangal dog from Turkey

This study has so far been the first attempt to characterize and quantify skull sexual variation in Kangal dog, by means of geometric morphometric techniques. A sample of 16 adult Kangal crania has been analyzed with this purpose. To obtain a full image of morphological pattern, digital pictures were taken from the ventral, left lateral, and dorsal sides of each skull, and a total of 16, 15, and 16 landmarks respectively were obtained on each image. Skull size and shape differed significantly in all aspects among different sexes, male skulls being bigger. Shape differences were observed mainly on zygomatic arch and muzzle on the dorsal view, pterygoid bone and articular surface to mandibular condyle in the lateral aspect, and cranial width and maxillary bone on the ventral view. Although the sample was comparatively small in number, being the first geometric morphometric approach applied on the Kangal dog, the obtained results will add vital information particularly to understand the cranial shape sexual dimorphism of this unique dog breed in Turkey.

Aberrant cell segregation in the craniofacial primordium and the emergence of facial dysmorphology in craniofrontonasal syndrome

Craniofrontonasal syndrome (CFNS) is a rare X-linked disorder characterized by craniofacial, skeletal, and neurological anomalies and is caused by mutations in EFNB1. Heterozygous females are more severely affected by CFNS than hemizygous males, a phenomenon called cellular interference that results from EPHRIN-B1 mosaicism. In Efnb1 heterozygous mice, mosaicism for EPHRIN-B1 results in cell sorting and more severe phenotypes than Efnb1 hemizygous males, but how craniofacial dysmorphology arises from cell segregation is unknown and CFNS etiology therefore remains poorly understood. Here, we couple geometric morphometric techniques with temporal and spatial interrogation of embryonic cell segregation in mouse mutant models to elucidate mechanisms underlying CFNS pathogenesis. By generating EPHRIN-B1 mosaicism at different developmental timepoints and in specific cell populations, we find that EPHRIN-B1 regulates cell segregation independently in early neural development and later in craniofacial development, correlating with the emergence of quantitative differences in face shape. Whereas specific craniofacial shape changes are qualitatively similar in Efnb1 heterozygous and hemizygous mutant embryos, heterozygous embryos are quantitatively more severely affected, indicating that Efnb1 mosaicism exacerbates loss of function phenotypes rather than having a neomorphic effect. Notably, neural tissue-specific disruption of Efnb1 does not appear to contribute to CFNS craniofacial dysmorphology, but its disruption within neural crest cell-derived mesenchyme results in phenotypes very similar to widespread loss. EPHRIN-B1 can bind and signal with EPHB1, EPHB2, and EPHB3 receptor tyrosine kinases, but the signaling partner(s) relevant to CFNS are unknown. Geometric morphometric analysis of an allelic series of Ephb1; Ephb2; Ephb3 mutant embryos indicates that EPHB2 and EPHB3 are key receptors mediating Efnb1 hemizygous-like phenotypes, but the complete loss of EPHB1-3 does not fully recapitulate the severity of CFNS-like Efnb1 heterozygosity. Finally, by generating Efnb1+/Δ; Ephb1; Ephb2; Ephb3 quadruple knockout mice, we determine how modulating cumulative receptor activity influences cell segregation in craniofacial development and find that while EPHB2 and EPHB3 play an important role in craniofacial cell segregation, EPHB1 is more important for cell segregation in the brain; surprisingly, complete loss of EPHB1-EPHB3 does not completely abrogate cell segregation. Together, these data advance our understanding of the etiology and signaling interactions underlying CFNS dysmorphology.

Geometric morphometric study of sexual dimorphism in malaysian mandibles

Background: Geometric morphometric is the statistical analysis of form based on Cartesian landmark coordinates. In this study, geometric morphometric techniques were used to study sexual dimorphism of mandible. Aims: The objectives were to determine mandible variation in size and shape, to determine the relationship between size and shape of mandible in different sexes, and to visualise allometry patterns of mandible. Methods: About 113 samples of adult human mandibles (65 males, 48 females) were analysed at the Universiti Kebangsaan Malaysia Medical Centre. Approximately 12 landmarks were placed on the 2-D image by landmarking software, and were analysed with MorphoJ. Results: The first five principal components were taken to represent the morphological variance with 83.64% cumulative variance. The mandible shape was used to determine sex. The variance visualization showed significant variation between male and female. The classification accuracy was 91.96%. Conclusion: Geometric morphometric is a good method to study sexual dimorphism of the mandible. Its potential may be developed in forensic anthropology to determine ancestry and age groups. MorphoJ and other softwares may be used in the application of geometric morphometric study of other bones.

Ontogenetic shape changes in the pelvis of the Greater Rhea (Aves, Palaeognathae) and their relationships with cursorial locomotion: a geometric morphometric approach.

Knowledge of the ontogenetic pattern of morphological features is essential to improve biological interpretations. The study of morphological features of the pelvic girdle and hind limb apparatus throughout growth is an excellent approach to understand how the skeletal morphology and muscles are interrelated during growth in a bird with a specialized mode of locomotion. The Greater Rhea (Rhea americana) is a large cursorial palaeognathous bird with long legs and powerful musculature. The postnatal shape changes of the pelvis of this bird were studied with geometric morphometric techniques, using landmarks and semilandmarks. In addition, regression analyses were used to explore the association between pelvic shape changes with muscle and body mass. The pelvises of 16 specimens of Rhea americana from 1 month old to adulthood were studied in dorsal and lateral views. Noticeable differences in pelvic shape were noted between ages, particularly in lateral view. In young birds, the pre- and post-acetabular ilium was subequal in length, whereas in adults the pre-acetabular ilium became shorter. In dorsal view, the main shape changes observed were the progressive thinning of both ilium portions and the elongation of the vertex craniolateralis ilii from chicks to adulthood. In this view, the only clear differentiation was between young and adult birds. Shape differences were influenced by body mass and pelvic muscles; the post-acetabular muscle mass explained the highest percentage of the variation. The specialized locomotion of Greater Rhea is reflected in their pelvic musculoskeletal system, in which the change to a longer post-acetabular ilium correlates with the growth of the powerful post-acetabular muscles. The actions of these muscles provide the necessary strength to support the body mass, minimize the body swinging movements and propel the body forward during locomotion. Bone morphology is affected by the forces produced by body mass and the muscle activity, demonstrating the presence of common growth mechanisms, which are primordial and gave rise to a functional and properly proportioned adult.

A Comparison of Traditional and Geometric Morphometric Techniques for the Study of Basicranial Morphology in Horses: A Case Study of the Araucanian Horse from Colombia.

Simple SummarySkull size and shape have been widely used to study domestic animal populations and breeds. Although several techniques have been proposed to quantify cranial form, few attempts have been made to compare the results obtained by different techniques. In this study, two morphometric methods were compared for their ability in describing external morphology. The use of geometric morphometrics combined with multivariate statistical methods is an efficient way to characterize shape and size, thus allowing greater understanding of locally adapted breeds. The Araucanian horse from Colombia inhabits the eastern plains of Arauca. The objective was to compare linear and geometric morphometrics applied to the morphology of the skull of the Araucanian horse, specifically in the basal cranial region. Twenty dry skulls of adult males were examined and were separated into two age groups based on molar eruption and wear. A photograph was taken and a 100 mm scale was placed over each sample. Linear values were obtained from the distance between homologous points from a set of reference points. For the geometric morphometrics analysis, eight paired and five mid-sagittal reference points were used. The geometric morphometric method was more discriminant than linear morphometry and it provides more information about the contour and shape of the face. Future studies should aim to understand the role of phenotypic plasticity in equine race variations and their genetic basis.Skull size and shape have been widely used to study domestic animal populations and breeds. Although several techniques have been proposed to quantify cranial form, few attempts have been made to compare the results obtained by different techniques. While linear morphometrics has traditionally been used in breed characterization, recent advances in geometric morphometrics have created new techniques for specifically quantifying shape and size. The objective of this study was to compare two morphometric methods for their ability to describe external morphology. For this purpose, 20 skull specimens of adult male Araucanian horses were examined. Two age categories were established (the “mature group”, M3 not fully erupted to moderately worn, n = 7; and the “senile group”, M3 totally erupted and highly worn, n = 13). Both methods showed that there were statistical differences between generations, but discrimination rates were different between methods with the geometric morphometric analysis obtaining a rate of 97.5%. Although linear morphometrics was found to be compatible with geometric morphometrics, the latter was better able to discriminate the two groups and it also provides more information on shape.

Morphological variation of Transcaucasian chub, Squalius turcicus in southern Caspian Sea basin using geometric morphometric technique

This work was conducted to study the patterns of morphological differences in body shape in Squalius turcicus De Filippi, 1865 from the most east (Atrak River) to the most west (Aras River) populations of the southern Caspian Sea basin using landmark-based geometric morphometric method to understand how the body shape alters in relation to geographical alternations or environmental characters of their habitats. A total of 102 specimens were collected from the Aras, Tajan, Atrak, Ghareh-Su, Khyer and Sefid rivers and after anesthesia, their left faces were photographed. To extract shape data, 14 homologous landmark-points were digitized and data after generalized procrustes analysis, analysed using principal component analysis, canonical variate analysis, cluster analysis, and Mantel test. The results showed significant differences between the body shape of six studied populations, mostly related to snout, base of the dorsal and anal-fins, body depth and pectoral fin position as result of phenotypic plasticity to the environmental features of their habitats. The Tajan and Atrak populations have a higher and lower body depth, and the Kheyr population a longer snout.

Bill morphology and biometrics of three sibling woodpecker species from sympatric populations

ABSTRACT Capsule Different methods of comparing bill morphology between woodpecker species show different, but not contradictory results. Aims Differences among similar, closely related species which co-occur are still highly debated. In such a scenario, species should diverge morphologically to reduce competition. We studied this phenomenon, in three closely related woodpecker species that co-occur in eastern Slovakia: Great Spotted Woodpecker Dendrocopos major, Syrian Woodpecker Dendrocopos syriacus and White-backed Woodpecker Dendrocopos leucotos. The Great Spotted Woodpecker has the widest niche and lives sympatrically with both Syrian and White-backed Woodpeckers, while the distributions of the latter two species do not overlap because of their use of different habitats. We predicted that Great Spotted Woodpeckers should differ morphologically from both sympatric species: Syrian and White-backed Woodpeckers. Methods Comparisons were made between species, based on dorsal and lateral views of maxilla using both geometric morphometric techniques and traditional measurements. Results We confirmed our hypothesis, and found significant differences in bill shape between Great Spotted Woodpecker and both congeners. This is in contrast to the observed higher similarity of Great Spotted Woodpecker and Syrian Woodpecker in traditional body measurements. However, surprisingly, Syrian Woodpecker and White-backed Woodpecker do not differ significantly in bill shape. Conclusions This work indicates that geometric morphometry appears to be a promising tool for the investigation of how interspecific competition influences the shape of the bill between co-occurring species.

Body shape comparison of Big-head carp with two variants of silver carp using geometric morphometric techniques

Body shape comparison of Big-head carp with two variants of silver carp using geometric morphometric techniques

Femoral Shape in Procyonids (Carnivora, Procyonidae): Morphofunctional Implications, Size and Phylogenetic Signal

Procyonids occur throughout the Americas and include ecologically diverse forms. They occupy diverse habitats and display a variety of locomotor modes and substrate preferences. Because of this ecological diversity, procyonids represent an interesting model for morphofunctional analysis of their postcranial skeleton. This work is an analysis of shape variation of the femur, a highly informative element of the appendicular skeleton of mammals, whose morphology reflects diverse locomotor abilities and is also related to body weight support and phylogeny. In this work, two femoral aspects were analyzed in all living procyonid genera within a wide comparative sample of carnivorans using 2D geometric morphometric techniques. Morphofunctional implications of the shape variations detected and relationships with locomotor modes and substrate preferences are discussed, as well as influence of body size and phylogeny. Analysis of the caudo-proximal shape indicated that procyonids present an intermediate morphology among carnivorans, but with some correlation with body size. In the analysis of distal femoral shape, procyonids were more separated among each other along Principal Component 1 and located on one extreme of the morphospace, while shape variation did not show association with body size. Even though the femoral shapes analyzed in the carnivoran sample showed significant phylogenetic signal, the latter was relatively low. In procyonids, the pattern of morphological variation of both femoral aspects does not agree with the phylogenetic structure. Therefore, most morphological variation found among procyonids can be related to known ecological characteristics of their locomotion or substrate preference and also partly explained by body size.

Potential adaptations for bipedalism in the thoracic and lumbar vertebrae of Homo sapiens: A 3D comparative analysis

A number of putative adaptations for bipedalism have been identified in the hominin spine. However, it is possible that some have been overlooked because only a few studies have used 3D and these studies have focused on cervical vertebrae. With this in mind, we used geometric morphometric techniques to compare the 3D shapes of three thoracic and two lumbar vertebrae of Homo sapiens, Pan troglodytes, Gorilla gorilla, and Pongo pygmaeus. The study had two goals. One was to confirm the existence of traits previously reported to distinguish the thoracic and lumbar vertebrae of H. sapiens from those of the great apes. The other was to, if possible, identify hitherto undescribed traits that differentiate H. sapiens thoracic and lumbar vertebrae from those of the great apes. Both goals were accomplished. Our analyses not only substantiated a number of traits that have previously been discussed in the literature but also identified four traits that have not been described before: (1) dorsoventrally shorter pedicles in the upper thoracic vertebrae; (2) dorsoventrally longer laminae in all five of the vertebrae examined; (3) longer transverse processes in the upper thoracic vertebrae; and (4) craniocaudally ‘pinched’ spinous process tips in all of the vertebrae examined. A review of the biomechanical literature suggests that most of the traits highlighted in our analyses can be plausibly linked to bipedalism, including three of the four new ones. As such, the present study not only sheds further light on the differences between the spines of H. sapiens and great apes but also enhances our understanding of how the shift to bipedalism affected the hominin vertebral column.

Morphometric evolution of Mimomys savini (Rodentia, Mammalia): A new view of its morphological changes

Mimomys savini is a very important arvicoline as it represents a useful biochronological tool in the study of the first human arrivals in Europe and its expansion across the continent. To date, evolution studies on this species have focused on its size changes and the loss of ancestral characteristics.This work sheds further light on the evolution of this taxon, through a study of the morphological changes in its first lower molar, using, for the first time, 2-D geometric morphometrics techniques based on landmark configurations. To do this, we have analyzed M. savini remains spanning 1.4 to 0.78 Ma from the Gran Dolina site (Sierra de Atapuerca, Spain), Barranco León site (Orce, Spain), and Barranc de la Boella site (Tarragona, Spain).Our results show a set of occlusal surface shape differences between the more recent and older populations. The oldest populations are characterized by a more developed lingual re-entrant angle 4 (LRA4); a less developed buccal re-entrant angle 3 (BRA3); a narrower lingual re-entrant angle 1 (LRA1); and a wider neck of the head of the anteroconid complex (ACC) than in more recent populations. Moreover, despite the increase in m1 length and width during the evolution of M. savini, it seems that the size of the occlusal surface decreased (maybe as a consequence of shape changes, such as neck width or the size of re-entrant angles).Finally, the shape and size comparisons of the populations studied reinforces previously proposed chronologies for Barranc de la Boella, and suggests a site age similar to that of Gran Dolina (section TD6 -TD5).

Divergent Morphology among Populations of the New Guinea Crocodile, Crocodylus novaeguineae (Schmidt, 1928): Diagnosis of an Independent Lineage and Description of a New Species

The freshwater crocodile inhabiting Papua New Guinea, currently recognized as Crocodylus novaeguineae, exhibits morphological, molecular, and ecological divergence between the northern and southern versants of the Central Highlands and occupies separate evolutionary trajectories. A robust body of work has long encouraged the formal description of New Guinea crocodiles from the southern versant of the highlands as a distinct lineage with a taxonomy that reflects diagnosed relationships. Here, we use geometric morphometric techniques to assess cranial shape variation between specimens from both versants and add to the diagnostic evidence supporting a more accurate taxonomy. Further, herein, we formally describe the southern variant as a distinct lineage (Hall's New Guinea Crocodile; Crocodylus halli, new species).

The Shape of Weaver: Investigating Shape Disparity in Orb-Weaving Spiders (Araneae, Araneidae) Using Geometric Morphometrics

Sexual size dimorphism in orb-weaving spiders is a relatively well-studied phenomenon, and numerous works have documented evolutionary variation in interspecific size and degree of dimorphism. To date, these studies have been largely limited to assessing the evolution of a single or few linear measurements correlated with body size. While the descriptive and comparative literature is rich with qualitative and linear comparisons that distinguish the sexes and characterize species, the extent to which interspecific or dimorphic variation in size correlates with morphological shape remains relatively unexplored. The carapace of spiders is generally conserved in shape, especially among members of the same family, but is neither well-characterized as a potential facet of spider sexual dimorphism nor as a variable structure overall. Here, we use geometric morphometric techniques to quantify differences in carapace shape among members of the family Araneidae and test for allometric influences on interspecific and dimorphic shape differences across orb-weavers. We show that females and males differ in shape, occupying overlapping but distinct areas of morphospace, with males having more piriform carapaces than females. Araneid spider subfamilies overlap substantially in morphospace, though interspecific differences in shape are generally greater than those distinguishing males and females of a species. Furthermore, we show that female carapace shape shows phylogenetic signal and is more conserved than is male shape. Carapace shape differences made evident from canonical variates analysis are congruent with the more mobile lifestyle adopted by males, as a broader carapace may support more robust leg musculature.

Northern Asian Pliocene–Pleistocene beremendiin shrews (Mammalia, Lipotyphla, Soricidae): a description of material from Russia (Siberia), Kazakhstan, and Mongolia and the paleobiology of Beremendia

AbstractBeremendiini is an extinct group of soricine shrews that were widely distributed during the Pliocene and Pleistocene. Their occurrence in China has been investigated, but their presence in northern Asian regions has remained poorly studied. This paper analyzes 56 fossil remains of Beremendiini collected from 16 early Pliocene to early Pleistocene localities in Russia (Siberia), Kazakhstan, and Mongolia and shows the presence of two beremendiin species:Beremendia fissidens(Petényi, 1864) andBeremendia minorRzebik-Kowalska, 1976. Northern AsianBeremendiaconsiderably vary in size and qualitative characteristics, although most of the different states have been identified in European or Chinese specimens. Through the application of geometric morphometric techniques, mandibular shape analyses reveal similarities between the members of the beremendiin generaPeisorexKowalski and Li, 1963,BeremendiaKormos, 1934, andLunanosorexJin and Kawamura, 1996. Shape analyses and comparisons of mandibular characteristics reveal ‘trophic’ analogies betweenBeremendiaandBlarinaspp. and a new model of ‘Mandible Swinging and Sliding’ (MSS-model) accounting for the similarities in mandibular morphology with implications for the understanding of the diet ofBeremendia.UUID:http://zoobank.org/ef92ee1a-3977-44b2-86d7-381665bcf78b

The many faces of synapsid cranial allometry

AbstractPrevious studies of cranial shape have established a consistent interspecific allometric pattern relating the relative lengths of the face and braincase regions of the skull within multiple families of mammals. In this interspecific allometry, the facial region of the skull is proportionally longer than the braincase in larger species. The regularity and broad taxonomic occurrence of this allometric pattern suggests that it may have an origin near the base of crown Mammalia, or even deeper in the synapsid or amniote forerunners of mammals. To investigate the possible origins of this allometric pattern, we used geometric morphometric techniques to analyze cranial shape in 194 species of nonmammalian synapsids, which constitute a set of successive outgroups to Mammalia. We recovered a much greater diversity of allometric patterns within nonmammalian synapsids than has been observed in mammals, including several instances similar to the mammalian pattern. However, we found no evidence of the mammalian pattern within Therocephalia and nonmammalian Cynodontia, the synapsids most closely related to mammals. This suggests that the mammalian allometric pattern arose somewhere within Mammaliaformes, rather than within nonmammalian synapsids. Further investigation using an ontogenetic series of the anomodontDiictodon felicepsshows that the pattern of interspecific allometry within anomodonts parallels the ontogenetic trajectory ofDiictodon.This indicates that in at least some synapsids, allometric patterns associated with ontogeny may provide a “path of least resistance” for interspecific variation, a mechanism that we suggest produces the interspecific allometric pattern observed in mammals.

Sex and Height Influence Neck Posture When Using Electronic Handheld Devices.

With increased tablet ownership in the United States comes increased levels of neck flexion compared to desktop or laptop computer use, and these neck postures have been linked to increases in neck pain. Importantly, tablet viewing postures can be achieved in multiple ways and could be determined by the morphology of the individual and/or other extraneous factors. In this study, we aim to preliminarily evaluate how neck postures vary during tablet use among individuals and link this variation to other factors such as sex, height, weight, presence/absence of temporomandibular joint disorder (TMD), and morphology of the head and neck. We analyzed two-dimensional landmarks placed on lateral-view radiographs of 22 participants (10 female and 12 male) seated in neutral, upright, fully flexed, semi-reclined, and reclined postures. We utilize geometric morphometric techniques, which are advantageous for evaluating shape variation and have not been extensively applied to biomechanical analyses. We found skeletal morphology to be significantly related to sex and height in all but the neutral posture (P < 0.05), and weight was marginally significantly related to shape in the semi-reclined posture (P = 0.047). Morphologically, male participants exhibited more flexion at the articulatio atlantooccipitalis than females, and females showed greater mandibular protrusion than males, although this result is likely related to height. No relationship was found between posture and TMD. This research establishes a framework for future work that uses geometric morphometric analyses to evaluate how neck postures vary in relation to TMD. Clin. Anat. 32:1061-1071, 2019. © 2019 Wiley Periodicals, Inc.

Endostructural morphology in hominoid mandibular third premolars: Geometric morphometric analysis of dentine crown shape

In apes, the mandibular third premolar (P3) is adapted for a role in honing the large upper canine. The role of honing was lost early in hominin evolution, releasing the tooth from this functional constraint and allowing it to respond to subsequent changes in masticatory demands. This led to substantial morphological changes, and as such the P3 has featured prominently in systematic analyses of the hominin clade. The application of microtomography has also demonstrated that examination of the enamel-dentine junction (EDJ) increases the taxonomic value of variations in crown morphology. Here we use geometric morphometric techniques to analyze the shape of the P3 EDJ in a broad sample of fossil hominins, modern humans, and extant apes (n = 111). We test the utility of P3 EDJ shape for distinguishing among hominoids, address the affinities of a number of hominin specimens of uncertain taxonomic attribution, and characterize the changes in P3 EDJ morphology across our sample, with particular reference to features relating to canine honing and premolar ‘molarization’. We find that the morphology of the P3 EDJ is useful in taxonomic identification of individual specimens, with a classification accuracy of up to 88%. The P3 EDJ of canine-honing apes displays a tall protoconid, little metaconid development, and an asymmetrical crown shape. Plio-Pleistocene hominin taxa display derived masticatory adaptations at the EDJ, such as the molarized premolars of Australopithecus africanus and Paranthropus, which have well-developed marginal ridges, an enlarged talonid, and a large metaconid. Modern humans and Neanderthals display a tall dentine body and reduced metaconid development, a morphology shared with premolars from Mauer and the Cave of Hearths. Homo naledi displays a P3 EDJ morphology that is unique among our sample; it is quite unlike Middle Pleistocene and recent Homo samples and most closely resembles Australopithecus, Paranthropus and early Homo specimens.

Outline-based geometric morphometric analysis to identify two Anopheles and three Culex mosquitoes in Thailand

Abstract. Chaiphongpachara T. 2019. Outline-based geometric morphometric analysis to identify two Anopheles and three Culex mosquitoes in Thailand. Biodiversitas 20: 1866-1872. Geometric morphometric (GM) techniques have become popular for applications in entomology studies, especially mosquitoes. Outline-based methods (OTLs) are one such form of GM technique used to analyze pseudo-landmarks on contours or boundary outlines. This study investigated the efficacy of an OTL to distinguish two species of Anopheles mosquitoes including An. epiroticus and An. subpictus s.l. and three species of Culex mosquitoes, including Cx. quinquefasciatus, Cx. visnui and Cx. whitmorei in Thailand and compared outlines, including internal outline 1 (IOL1), internal outline 2 (IOL2) and external outline (EOL) within the mosquito wing to assess the optimal outline for analysis. The results indicated that OTLs were highly effective with certain species and each outline had the potential difference for identification. For size analysis, An. epiroticus had a mean perimeter length of IOL2 and EOL length larger than An. subpictus. Different sizes between species was found in IOL1, which was statistically significant after Bonferroni test (p &lt; 0.05). Culex size analysis of IOL2 and EOL demonstrated a statistical difference for all species while size difference patterns between outlines found that IOL1 differed from other outlines. While shapes in two Anopheles of all cells were different between species, there was statistical significance based on Mahalanobis distances (p &lt; 0.05). Almost all pairwise Mahalanobis distances between Culex species of IOL1, IOL2 and EOL established statistical differences, except for pairs of Cx. visnui and Cx. whitmorei via IOL2 analysis.&#x0D;

Approaching Nutritional Status by Means of Geometric Morphometric Methods (P11-129-19)

ObjectivesTo analyse the correlation between shape variables and anthropometric variables in children aged 6–59 months for assessing acute malnutrition using geometric morphometrics. MethodsA sample of 411 Senegalese malnourished (n = 148), well-nourished (n = 156) and Spanish well-nourished (n = 107) children aged 6–59 months was studied regarding WHO considerations. Anthropometrical measurements of weight, height, middle-upper arm circumference (MUAC), head circumference and sitting height were used to assess the nutritional status. Weight for height and MUAC z-scores were calculated. A set of 36 anatomical and/or osteologically-based landmarks were identified on the body of the children along with 108 semi-landmarks used to capture the body contour on the frontal view of the body image. Shape differences among children were analysed and visualised considering the continuous distribution of the anthropometrical variables by means of Geometric Morphometric techniques. Regression analyses were carried out to assess the correlation between shape and anthropometrical variables. The effect of age and sex variations was also explored using multivariate analysis. ResultsSignificant differences on height (F = 86,29; P < 0.01), weight (F = 13,80; P < 0.01), MUAC (F = 53,45; P < 0.01), head circumference (F = 59,79; P < 0,01) and sitting height (F = 748,81; P < 0,01) were found between the three groups of children analysed. In the Spanish population statistical significant differences were described for weight and height between children under and over 24 months while in the Senegalese sample, all anthropometric variables exhibited significant differences (P < 0,01). The first two Principal Components showed the morphometrical variability of children shape along the anthropometrical variables. Age and sex effect showed also significant different patterns in both shape and morphometrical variables (P < 0.01). ConclusionsWeight for height and MUAC for age z-scores are well descriptors of shape differences among children. GM techniques are useful to study morphometrical changes in the anterior body view of children aged 6–59 months when different factors are analysed. In our study, all of the anthropometric values contributed to explain children’s entire body shape in anterior view. The subdivision of children into age groups under and over two years old is important to visualize the differences achieved due to the effect of the various analysed. Funding SourcesChildren’s Investment Fund Foundation.