Morphometric Approach Research Articles

New in morphometry: Geometric morphometry of the external female genitalia of Triatominae (Hemiptera: Reduviidae)

The study of geometric morphometry has an impact on Triatominae studies. Currently, several taxonomic and systematic studies use this approach. The Triatominae subfamily comprises three fossil species and 154 extant species potentially capable of transmitting Trypanosoma cruzi, the causative agent of Chagas disease. This study aims to evaluate the external female genitalia of adult triatomines using multivariate geometric morphometric approaches, not only for validation but also for systematic inferences. Specimens belonging to the genera Panstrongylus, Psammolestes, Rhodnius, and Triatoma were evaluated, in addition to two species previously included in Triatoma: T. longipennis and T. phyllosoma. The results show that the external female genitalia have operational morphology and allow characterization of the species and the genera of the Triatominae. In addition, the multivariate technique enabled delimitation of the phylogenetic relationships of the subfamily, presenting results consistent with systematic studies. It can be concluded that the external female genitalia evaluated by geometric morphometry is a useful character for the taxonomy and systematics of Triatominae.

Ecomorphology of the tarsometatarsus of waterfowl (Anseriformes) based on geometric morphometrics and its application to fossils.

Anseriformes is a diverse group of birds that comprises screamers, the Magpie Goose, and swans ducks and geese, with a relatively rich fossil record. Waterfowl live in close relation to water bodies, but show a diversity of locomotory habits, being typically categorized as walkers, dabblers, and divers. Owing to its functional significance and high preservation potential, the tarsometatarsus has been considered to be a "key" element upon which to base ecomorphological inferences in fossil waterfowl. For instance, based on features of the tarsometatarsus the Miocene flightless duck Cayaoa bruneti and the Oligocene-Miocene large waterfowl Paranyroca have been inferred as divers. Herein, we use a geometric morphometric approach and comparative methods to assess the phylogenetic and ecomorphological signals in the shape and size of waterfowl tarsometatarsi in relation to their locomotory habits. We also apply phylogenetic flexible discriminant analysis (pFDA) to test the inferred diving habits in the extinct waterfowl Cayaoa and Paranyroca. Extant waterfowl species are largely distributed according to their locomotory habit along the main axis of variation in the shape space, a pattern mirrored by the phylogenetic generalized least squares model, which shows that a third of the shape variation is significantly explained by the habit. The pFDA reclassifies correctly almost all extant species and classified with high posterior probabilities the fossil Cayaoa and Paranyroca as a diver and as a dabbler, respectively. Our quantitative multivariate approach confirms the tarsometatarsus as a useful source of data upon which reliably assesses locomotory habits of fossil waterfowl.

Age dependent changes in pelvic shape during adulthood.

The human pelvis has been reported to change in shape throughout adult lifetime, and also the expression of parturition scars, or "pelvic features", increases with age. However, little is known about the causes and timing of these changes. Here we investigate changes in pelvic shape and the expression of pelvic features by applying a comprehensive geometric morphometric approach to a modern sample of 167 adult individuals with known age, parity, and cause of death. Our results confirm that the pelvis changes in shape during adult life, but to a larger magnitude in females compared to males. Moreover, females showed three different phases of pelvic shape change, coinciding with the main period of reproduction (from 17 to about 37-40 years), the period after that but before menopause, and the postmenopausal period (after 50 years of age). Males exhibited two phases with relatively similar shape changes. The expression of parturition scars increased in females until about 40 years of age and stayed relatively constant thereafter. Only a very weak increase of feature expression was found in males. We hypothesize that changes of adult pelvic shape and feature expression result from a combination of hormone-mediated and mechanically induced bone remodeling. Estrogen-induced and pregnancy-related bone remodeling dominates in premenopausal women, whereas bone remodeling in response to mechanical factors may underlie pelvic shape changes in men and postmenopausal women. The continual widening of the birth canal during the reproductive period eases childbirth in a population, but it is unlikely that this remodeling pattern specifically evolved as an obstetric adaptation in the human lineage. The highly conserved endocrine system and estrogen-induced pelvic bone remodeling were already in place when the neonatal brain increased in the human lineage. But the regularity control of this conserved pathway may have been "fine-tuned" by selective forces in the human lineage.

A Hidden Diversity in the Atlantic and the SE Pacific: Hamatipedidae n. fam. (Crustacea: Tanaidacea)

A new family of paratanaoidean Tanaidacea, the hamatipedids, formerly part of the Typhlotanaidae, is established to accommodate three genera (Hamatipedaand two new). Deep-sea hamatipedids collected from four sites in the Atlantic (Argentine and Guiana basins) and 14 sites from the Southeast coast of Australia were studied using a taxonomic approach combining morphological and morphometric data. Four new species ofHamatipedaand one of a new genus are described from different deep-sea areas of the Atlantic and Pacific oceans.Hamatipeda simaoriginally classified withinHamatipeda, is transferred to a new genus. We observed that several morphometric characters (i.e., length of the last two pereonites) in different life-stages of one of the newHamatipedaspecies (neuter, manca-2, and manca-3) are correlated with the total body length (TBL). Applying a morphometric approach, we aimed: (1) to identify those ontogenetic-dependent characters, and (2) to detect the characters, which can be used in discrimination of Hamatipedidae species, regardless their life-stage.

Size doesn’t matter shape does: A morphological study of pitcher plant in distinct forest canopy structures

Light exposure from the sun is the most crucial variable for producing optimal pitcher size and colour variation in Nepenthes. This study aimed to observe the effect of forest canopy structure on morphological character of Nepenthes ampullaria’s pitcher parts (longitudinal, front, and peristome) both on size and shape using Geometric morphometric (GM) approach and its prey diversity. We classified the forest canopy structure into two categories: inside the canopy and open space area (gap). We used Unmanned Aerial Vehicle (UAV) images to build Canopy Height Model (CHM). Then, ForestGapR R package used to analyse and generated the forest gaps area. The prey specimens and photograph samples comprised from 9 individuals with three lower pitchers in open space area with high light exposure as well as shaded area inside the canopy. Total of 54 images were marked by point and curve to generated a landmark analysis using GeoMorph R package. Based on GM analysis, we observed that the forest canopy structure could affect Nepenthes pitcher shape but not in pitcher size. Our field result revealed Nepenthes ampullaria likely dominated by darker colour with a red spot in the shaded area and bright green colour in the open. However, based on our study the pitcher in shaded area inside the canopy have a larger number of prey species than the open area.

Benchmarking off-the-shelf statistical shape modeling tools in clinical applications.

Statistical shape modeling (SSM) is widely used in biology and medicine as a new generation of morphometric approaches for the quantitative analysis of anatomical shapes. Technological advancements of in vivo imaging have led to the development of open-source computational tools that automate the modeling of anatomical shapes and their population-level variability. However, little work has been done on the evaluation and validation of such tools in clinical applications that rely on morphometric quantifications(e.g., implant design and lesion screening). Here, we systematically assess the outcome of widely used, state-of-the-art SSM tools, namely ShapeWorks, Deformetrica, and SPHARM-PDM. We use both quantitative and qualitative metrics to evaluate shape models from different tools. We propose validation frameworks for anatomical landmark/measurement inference and lesion screening. We also present a lesion screening method to objectively characterize subtle abnormal shape changes with respect to learned population-level statistics of controls. Results demonstrate that SSM tools display different levels of consistencies, where ShapeWorks and Deformetrica models are more consistent compared to models from SPHARM-PDM due to the groupwise approach of estimating surface correspondences. Furthermore, ShapeWorks and Deformetrica shape models are found to capture clinically relevant population-level variability compared to SPHARM-PDM models.

A tale of bifaces from southern peninsular India (British Museum and Musée de l'Homme collections): a geometric morphometric and classical approach

Bifacial tools (especially handaxes and cleavers) have played an important role in the Lower Palaeolithic studies trying to decode Acheulean lifeways through them. The methodological approach based on classical metrical analysis, could be insufficient and often subjective, especially in instances of asymmetrical tools, and incorrect orientation for capturing the morphological data. Recent years have seen the application of geometric morphometric methods on lithic tools (2D contours and 3D volumetric forms) as an accurate, efficient and objective method of data collection. This alternative approach has the additional advantage of being both interactive and reversible analytic process, reducing the time and effort in collection of data. Traditionally the museum collections of Palaeolithic artefacts of old surveys and fieldworks, are seldom subject to study due to their incomplete and often doubtful or mixed context. In the current study, both geometric morphometric on 2D contour analysis as well as classical techno-typological analytical methods has been applied to bifaces from Southern Peninsular Indian Palaeolithic kept in the British Museum (London, UK) and Musée de l’Homme (Paris, France). The aim of this study is to highlight the complementary nature of both analytical methods in deciphering and throwing light on the patterns of bifaces (handaxes and cleavers), their technological variability and stability and to identify if there are regional technological trends. The results obtained from both classical analysis and geometric morphometric analysis allow to show that handaxes were highly variable in both the regions while the cleavers show high standardization. While the former approach throws light on the knapping techniques and preferences, the latter complement the results with the shape preferences and variations across regions.

Cylindrospermopsin impairs zebrafish (Danio rerio) embryo development

Cyanotoxins are among common contaminants that can impair human, animal, and environmental health. Cylindrospermopsin (CYN) is an abundant form of cyanotoxins elevated following algal bloom in the water worldwide. Previous studies have described CYN effects on several organs in mammals. However, little is known about its toxicity mechanisms in other vertebrates. This study aims to characterize the developmental effects of CYN using zebrafish larvae as an aquatic model organism. A wide range of CYN concentrations (0–2000 μg/L) was tested using a morphometric approach for survival, hatching, various growth and developmental abnormalities. We also investigated the expression of genes related to oxidative stress, osmoregulation, and thyroid function. Exposure to CYN resulted in decreased growth, increased developmental abnormalities such as pericardial and yolk sac edema as well as swim bladder absence. In addition, CYN increased tr1a, and decreased dio1 and dio3 transcript levels which are involved in thyroid-mediated function. It also increased transcript levels related to oxidative stress, including hsp70, ahr1a, cyp1a, gpx and cat. Lastly, CYN exposure increased aqp3a and decreased dab2, which are involved in osmoregulation with a threshold of 10 μg/L. The present study demonstrates multiple effects of exposure to environmentally relevant CYN concentrations in zebrafish embryos.

Exploring sexual dimorphism of human occipital and temporal bones through geometric morphometrics in an identified Western‐European sample

AbstractSex estimation is a paramount step of bioprofiling in both forensic anthropology and osteoarchaeology. When the pelvis is not optimally preserved, anthropologists commonly rely on the cranium to accurately estimate sex. Over the last decades, the geometric morphometric (GM) approach has been used to determine sexual dimorphism of the crania, in size and shape, overcoming some difficulties of traditional visual and metric methods. This article aims to investigate sexual dimorphism of the occipital and temporal region through GM analysis in a metapopulation of 50 Western‐European identified individuals. Statistical analyses were performed to compare centroid size and shape data between sexes through the examination of distinct functional modules. Regression and Procrustes ANOVA were used to examine allometric and asymmetrical implications. Discriminant functions, combining size and shape data, were established. Significant dimorphism in size was found, with males having larger crania, confirming the major influence size has on cranial morphology. Allometric relationships were found to be statistically significant in both right and left temporal bones while shape differences between sexes were only significant on the right temporal bone. The visualization of the mean consensus demonstrated that males displayed a larger mastoid process associated with a reduced mastoid triangle and less projected occipital condyles. This exploratory study confirms that GM analysis represents an effective way to quantitatively capture shape of dimorphic structures, even on complex rounded ones such as the mastoid region. Further examination in a larger sample would be valuable to design objective visualization tools that can improve morphoscopic sex estimation methods.

Evolution of flower allometry and pigmentation in Mammillaria haageana (Cactaceae)

BackgroundA puzzle in evolution is the understanding of how the environment might drive subtle phenotypic variation, and whether this variation is adaptive. Under the neutral evolutionary theory, subtle phenotypes are almost neutral with little adaptive value. To test this idea, we studied the infraspecific variation in flower shape and color in Mammillaria haageana, a species with a wide geographical distribution and phenotypic variation, which populations are often recognized as infraspecific taxa.ResultsWe collected samples from wild populations, kept them in the greenhouse for at least one reproductive year, and collected newly formed flowers. Our first objective was to characterize tepal natural variation in M. haageana through geometric morphometric and multivariate pigmentation analyses. We used landmark-based morphometrics to quantify the trends of shape variation and tepal color-patterns in 20 M. haageana accessions, belonging to five subspecies, plus 8 M. albilanata accessions for comparison as the sister species. We obtained eight geometric morphometric traits for tepal shape and color-patterns. We found broad variation in these traits between accessions belonging to the same subspecies, without taxonomic congruence with those infraspecific units. Also the phenetic cluster analysis showed different grouping patterns among accessions. When we correlated these phenotypes to the environment, we also found that solar radiation might explain the variation in tepal shape and color, suggesting that subtle variation in flower phenotypes might be adaptive. Finally we present anatomical sections in M. haageana subsp. san-angelensis to propose some of the underlying tepal structural features that may give rise to tepal variation.ConclusionsOur geometric morphometric approach of flower shape and color allowed us to identify the main trends of variation in each accession and putative subspecies, but also allowed us to correlate these variation to the environment, and propose anatomical mechanisms underlying this diversity of flower phenotypes.

Crania Canaria 2.0: construyendo una colección virtual de cráneos

El Museo Canario stores a large collection of aboriginal skulls that have been essential to the study of the origin and chronology of the population of the Canary archipelago since the 19th century. Regrettably, research has been dominated by biased and racial interpretations of both bioarchaeological and cultural evidence. When scientific racism and craniometric studies were rejected, studies of the Canarian indigenous skulls variability was also abandoned without replies. However, digital technologies and virtual sciences allow us to improve research and re-evaluate old paradigms. In this work, we present a digitalisation project aiming to construct a virtual database of the indigenous Canarian skulls, using a simple method of digitalisation that is very suitable to deal with large collections- The procedure, involving a portable 3D structured light scanner has allowed us to digitally reproduce more than 400 skulls stored at Museo Canario. This work offers a wide variety of possibilities for archaeology and anthropology. The versatility of 3D digital models enables the generation of interactive documentation, educational material for digital conservation and dissemination purposes. Indeed, 3D models are easily shared and can be displayed over diverse web-based repositories and online platforms and so, creating virtual online museums. We have created a profile in Sketchfab (https://sketchfab.com/craniacanaria2.0) where we intend to upload gradually the complete virtual collection of skulls we have realised. Moreover, digital skulls can serve as research objects. We discuss the advantages of studying 3D objects in a computerised environment, which includes traditional anthropometric studies (linear measurements and angles) but also 3D geometric morphometric approaches. In fact, in future studies, we will apply 3D geometric morphometrics for reassessing skull variation of ancient Canarians going beyond old paradigms and taking into account the latest advances in archaeology, anthropology and genetics in Canarian research. Highlights:- El Museo Canario stores an exceptional human skull collection that has served as the basis for numerous studies seeking to reveal the origin and chronology of the indigenous population.- This study presents an easy methodology for obtaining digital imagery using a 3D surface scanner, which allows constructing a virtual skull collection comprising more than 400 individuals.- Virtual 3D models have numerous advantages and applications in anthropology and archaeology, not only improving research but also permitting the re-evaluation of old paradigms.

Study on the Relationship between Richness and Morphological Diversity of Higher Taxa in the Darkling Beetles (Coleoptera: Tenebrionidae)

Many studies have found that the correlation between species richness (SR) and morphological diversity (MD) is positive, but the correlation degree of these parameters is not always consistent due to differences in categories and various ecological factors in the living environment. Based on this, related studies have revealed the good performance of using higher taxa in biodiversity research, not only by shifting the testing group scale from local communities to worldwide datasets but also by adding different taxonomic levels, such as the genus level. However, it remains unclear whether this positive correlation can also be applied to other categories or groups. Here, we evaluated the applicability of higher taxa in the biodiversity study of darkling beetles by using 3407 species (9 subfamilies, 89 tribes, and 678 genera), based on the correlation between taxa richness and morphological diversity in the tribe/genus/species. In addition, the continuous features prevalent in the tenebrionids, pronotum and elytron, were selected, and the morphological diversity of various groups was obtained by the geometric morphometric approach to quantify the morphologic information of features. This study found that genus/species richness in subfamilies Pimelinae and Stenochiinae was positively correlated with the change trend of MD, and the correlation between the MD of elytron and taxa richness gradually decreased from the tribe-level to the genus-level to the species-level test. The results confirm the stable morphology and simple function of the elytron and the applicability of tribe level in biodiversity research.

First report of the zoonotic nematode Baylisascaris procyonis in non-native raccoons (Procyon lotor) from Italy

Baylisascaris procyonis is a nematode parasite of the raccoon (Procyon lotor), and it can be responsible for a severe form of larva migrans in humans. This parasite has been reported from many countries all over the world, after translocation of its natural host outside its native geographic range, North America. In the period between January and August 2021, 21 raccoons were cage-trapped and euthanized in Tuscany (Central Italy), in the context of a plan aimed at eradicating a reproductive population of this non-native species. All the animals were submitted for necroscopic examination. Adult ascariids were found in the small intestine of seven raccoons (prevalence 33.3%). Parasites have been identified as B. procyonis based on both morphometric and molecular approaches. The aim of the present article is to report the first finding of this zoonotic parasite from Italy, highlighting the sanitary risks linked to the introduction of alien vertebrate species in new areas.Graphical

Craniofacial Dysmorphology in Infants With Non-Syndromic Unilateral Coronal Craniosynostosis.

Unilateral coronal craniosynostosis (UCS) is a congenital disorder resulting from the premature suture fusion, leading to complex primary and compensatory morphologic changes in the shape of not only the calvarium and but also into the skull base. This deformity typically requires surgery to correct the shape of the skull and prevent neurologic sequelae, including increased intracranial pressure, sensory deficits, and cognitive impairment. The present multicenter study sought to reverse-engineer the bone dysmorphogenesis seen in non-syndromic UCS using a geometric morphometric approach. Computed tomography scans for 26 non-syndromic UCS patients were converted to three-dimensional mesh models. Two hundred thirty-six unique anatomical landmarks and semi-landmarked curves were then plotted on each model, creating wireframe representations of the Patients' skulls. Generalized Procrustes superimposition, Principal Component Analysis, and heatmaps identified significant superior displacement of the ipsilateral orbit ("harlequin" eye deformity), anterior displacement of the ear ipsilateral to the fused coronal suture, acute deviation of midline skull base structures ipsilateral to the fused coronal suture and flattening of the parietal bone and associated failure to expand superiorly. The described technique illustrates the impact of premature coronal suture fusion on the development of the entire skull and proposes how bone dysmorphology contributes to the Patients' neurologic sequelae. By bridging novel basic science methodologies with clinical research, the present study quantitatively describes craniofacial development and bone dysmorphogenesis.

Assessing the diversity of hidden dental morphology in Hyperodapedontinae rhynchosaurs (Archosauromorpha, Rhynchosauria)

ABSTRACT The Hyperodapedontinae taxa are mainly diagnosed by characters from the maxillomandibular apparatus. Here we report two Hyperodapedon specimens from Brazil with apically serrated teeth crowns, which led to the identification of one new non-conical maxillary tooth morphotype, Sh, and the first records of serrated teeth in Rhynchosauria. The known types of pyramidal crowns are here expanded to three morphotypes (P1, P2, P3). Flutes, only reported for Hyperodapedon huxleyi (India), were identified in Hyperodapedon sp. and Teyumbaita sulcognathus (Brazil). Using qualitative and morphometric geometric approaches, we investigated whether the maxillary crown morphology is taxonomically informative or reflects ontogeny. The qualitative analysis demonstrated that crown morphology is not taxonomically constrained. The geometric morphometric analysis revealed that the maxillary crown shape varies according to the relative size and form of the tooth plate, parameters related to ontogeny. Flutes and serrations are recorded in Carnian hyperodapedontines from Brazil and India, a restrained paleolatitudinal range of Gondwana. The lack of information concerning dental ornamentations in other hyperodapedontines from the same latitudinal belt (e.g. Argentina) should be due to the scarcity of more detailed studies focused on crown morphology. Our results open the possibility for further studies focusing on hidden details of Rhynchosauria dental morphology.

Filling gaps in the biology of the endemic and threatened freshwater shrimp Macrobrachium candango (Caridea: Palaemonidae) through basic morphometric and reproductive approaches

Macrobrachium candango Mantelatto, Pileggi, Pantaleão, Magalhães, Villalobos and Álvarez, 2021 is an endemic shrimp species to the Brazilian Central-West region (Brasília, Federal District). The present study aims to analyze the relative growth, morphometry, morphological sexual maturity, and fecundity of this species. Specimens were collected from tributaries of the Paranoá Lake hydrographic basin, Brasília, during sporadic periods between 1983 and 2012. Relative growth was analyzed for different structures (carapace, abdomen, second abdominal pleura, merus, carpus, and propodus). The laterality and heterochely patterns were evaluated based on the dimensions of the propodus length. Fecundity was calculated as the average total number of eggs per female and egg size was measured to obtain the volume. There were differences in relative growth (p < 0.05) of the structures analyzed between juveniles and adults, and distinct allometric patterns were observed between the life stages, which could reflect the habit of these animals at each developmental stage. No pattern of laterality and heterochely was observed between the chelipeds of the animals analyzed (p > 0.05). The lack of laterality may indicate that this species directs energy to the smallest propodus when the largest propodus is injured. Egg volume ranged from 4.41 to 7.71 mm3, and fecundity ranged from 38 to 61 eggs, indicating a life cycle with abbreviated larval development. The characteristics presented herein are unprecedented for M. candango and present relevant information needed to assess the conservation status of this species, which is currently threatened.

Shape variation in head scales of species of the genus Ophiomorus DUMÉRIL &amp; BIBRON, 1839 in Iran, a geometric morphometrics approach

Twelve species of the genus Ophiomorus DUMÉRIL & BIBRON, 1839 have been identified and introduced so far and seven species of this genus have been found in Iran which include four endemic species and three nonendemic species. Although geometric morphometry is a powerful tool to analyze morphological changes, the discovery and identification of these species have long relied on traditional morphometric analysis. In this study, geometric morphometric analyses were used to determine the geometric morphometrics of different species of the genus Ophiomorus in Iran. The Multi Focus technique was used to obtain the best image of the dorsal surface of the head. Two types of Landmarks 1 and 3 were used to obtain geometric information from the scales of the head. To obtain two-dimensional coordinates, landmarks were digitized using tpsDig. For all landmarks, Procrustes Landmark or GPA analysis was performed using PAST software. Also, all landmarks were analyzed by PCA or Principal Components in PAST software based on the variance-covariance matrix between different groups and OTUs. The results showed that the most changes occurred in the head scales of O. persicus and O. maranjabensis. In O. nuchalis populations, an OTU1 was found based on changes in the head scales, being no overlap in the wireframe graph. This population (OTU 1) is distributed in central regions of the Iranian plateau and phylogenetic studies are needed to confirm it as a new species.

Insight into the noble crayfish morphological diversity: a geometric morphometric approach

The noble crayfish (Astacus astacus), a keystone species of high ecological, economic, and cultural importance in Europe, is threatened due to a long-term population decline caused by anthropogenic pressure on its habitats, the presence of non-indigenous invasive crayfish species and climate change. Since the effective protection of the remaining populations requires conservation measures based on the comprehensive knowledge of the species, including good understanding of its genetic and morphological variability, our aim was to study morphological features of the noble crayfish in Croatia using geometric morphometrics for the first time. We applied two-dimensional geometric morphometrics to find morphological differences among 15 populations of the noble crayfish from Croatian freshwater habitats, grouped according to previously established (a) mitochondrial (genetic) lineages, (b) genetic clusters inferred from nuclear microsatellites, as well as (c) river basins and (d) habitat types (lotic, lentic). Overall, the results indicated the existence of morphological diversity among the studied populations of the noble crayfish in Croatia. Shape analysis showed differences in cephalon based on crayfish affiliation to different genetic lineages, genetic clusters, river basins and habitat types. Our study provided novel insights into morphological diversity of the endangered noble crayfish in the area of its high genetic diversity.

Model-based plant phenomics on morphological traits using morphometric descriptors.

The morphological traits of plants contribute to many important functional features such as radiation interception, lodging tolerance, gas exchange efficiency, spatial competition between individuals and/or species, and disease resistance. Although the importance of plant phenotyping techniques is increasing with advances in molecular breeding strategies, there are barriers to its advancement, including the gap between measured data and phenotypic values, low quantitativity, and low throughput caused by the lack of models for representing morphological traits. In this review, we introduce morphological descriptors that can be used for phenotyping plant morphological traits. Geometric morphometric approaches pave the way to a general-purpose method applicable to single units. Hierarchical structures composed of an indefinite number of multiple elements, which is often observed in plants, can be quantified in terms of their multi-scale topological characteristics using topological data analysis. Theoretical morphological models capture specific anatomical structures, if recognized. These morphological descriptors provide us with the advantages of model-based plant phenotyping, including robust quantification of limited datasets. Moreover, we discuss the future possibilities that a system of model-based measurement and model refinement would solve the lack of morphological models and the difficulties in scaling out the phenotyping processes.

Morphological Variation in the Martinican Subspecies White-Breasted Thrasher (&amp;lt;i&amp;gt;Ramphocinclus brachyurus brachyurus&amp;lt;/i&amp;gt;)

The White-breasted Thrasher (Ramphocinclus brachyurus) is the smallest passerine bird in the Mimids family. Ranked as “endangered” in the IUCN list, the demographic distribution of this species is spread unevenly across two islands in the Lesser Antilles. The Saint-Lucian subspecies, Ramphocinclus brachyurus sanctaeluciae, was estimated to number between 1200 and 1700 individuals, whereas the Martinique subspecies, Ramphocinclus brachyurus brachyurus, was estimated at between 200 and 400 individuals. As an endemic rare species with a high risk of extinction, the Martinique subspecies should be regarded as a conservation priority. The small size of the Martinique subspecies population, its restricted geographical range, and its narrow habitat tolerance make it quite difficult to study. The variability of morphological traits in this subspecies has not been biostatistically analyzed recently. In order to update knowledge and fill in any gaps, we have used the morphometric approach to study the morphological variability of the Martinique subspecies. The study site is a small peninsula located in the northeast of the island of Martinique (French West Indies) known as “la Caravelle”. We captured 63 White-breasted Thrashers which were marked, measured, and sexed before being released. We did not observe any significant differences between the sexes, signifying an absence of sexual dimorphism. However, we were able to observe a significant variation in morphological traits between individuals measured inside and outside the national protected area of Caravelle. The body mass-tarsus ratio was equal at both sampled sites, something which could potentially be a clue to the bird’s adaptation to different habitats.