Limb Shape Research Articles

Quantifying graduation of layered below-the-knee compression garment combinations using a model-based assessment

ObjectiveOften people with lymphedema and vascular conditions will be prescribed layered compression garments to assist them in donning their garments and improve treatment compliance. However, little evidence of the interface pressures produced by these layered garments is available. In the present study, we explored the pressures produced by layering high and low class below-the-knee compression garment combinations and quantified the graduation of these combinations to understand the effect that layer order might have on the interface pressure. MethodsThe present study used a mechanical test design to measure the interface pressure at four sites (B, smallest ankle dimension; B1, circumference at Achilles tendon and gastrocnemius muscle junction; C, widest calf dimension; and D, below the knee) for 30 combinations of low and high class compression garments using a PicoPress (Microlab Elettronica, Ponte San Nicolò, Italy). ResultsThe results demonstrated a pattern consistent with graduation for sites B1 to D for 100% of the garment combinations. However, the graduation was reversed for sites B to B1 for 100% of the garment combinations, possibly due to limitations regarding the shape of the model limb. The results indicated no significant differences in the interface pressure when the higher class garment was applied as the bottom layer vs the top layer. A strong correlation (R > 0.95; P < .001) was between the actual pressures produced by the combinations of the garments and the expected pressure determined by summing the pressures of the individual garments. ConclusionsGraduation was observed from site B1 to site D, indicating that double layering of these garment combinations maintained guideline adherence. Layering the garments produced pressures that were, in general, cumulative of the pressure from each garment alone, with some variance. Because of the uncertainty of the B site results in the present study, the clinical implications in relation to the primary aim are limited. The findings from the secondary aim suggest that clinically, garment wearers can don their layered garments in any order and achieve the same interface pressure results.

A qualitative study on stakeholder perceptions of digital prosthetic socket fabrication for transtibial amputations.

Digital residual limb shape capture (three-dimensional [3D] scanning), computer-assisted design (CAD), and computer-assisted manufacturing with 3D printing technology show promise for a completely digital process of fabricating prosthetic sockets for patients with limb loss. The effectiveness and quality of digitally designed 3D-printed lower extremity prosthetic sockets is understudied, and there is lack of data on the patient and prosthetist experiences with this digital workflow. To obtain stakeholder feedback on the feasibility and acceptability of using a completely digital prosthetic fabrication process consisting of 3D scanning, CAD, and 3D printing in a rehabilitation setting for adults with transtibial limb amputations. Qualitative design. Study participants with a transtibial-level amputation were fit with a prosthetic socket fabricated using digital shape capture with a 3D scanner, CAD, and 3D printing in addition to a traditionally handcasted manually fabricated socket. Participants tried on and evaluated both sockets. Semistructured interviews took place after the fitting appointments. A focus group was conducted with prosthetists to obtain their feedback. Audio data were transcribed verbatim, and an inductive content analysis was undertaken. Eleven patient participants and 3 prosthetists identified 4 main themes: 1) openness and enthusiasm for digital prosthetic fabrication; 2) relative advantages of digital fabrication vs. traditional socket fabrication; 3) readiness of the technology used for adoption in practice; and 4) digital prosthetic workflow and 3D printing implementation considerations. Patients and prosthetists were enthusiastic about digital prosthetic socket fabrication and saw potential advantages over traditional methods. Both patients and prosthetists had concerns about the durability, safety, and aesthetics of the 3D printed sockets in this study. Further studies are needed to optimize digital prosthetic fabrication with 3D printing in prosthetic practice.

Use of streamflow indices to identify the catchment drivers of hydrographs

Abstract. Time irreversibility or temporal asymmetry refers to the steeper ascending and gradual descending parts of a streamflow hydrograph. The primary goal of this study is to bring out the distinction between streamflow indices directly linked with rising limbs and falling limbs and to explore their utility in uncovering processes associated with the steeper ascending and gradual descending limbs of the hydrograph within the time-irreversibility paradigm. Different streamflow indices are correlated with the rising and falling limbs and the catchment attributes. The key attributes governing rising and falling limbs are then identified. The contribution of the work is on differentiating hydrographs by their time irreversibility features and offering an alternative way to recognize primary drivers of streamflow hydrographs. A series of spatial maps describing the streamflow indices and their regional variability in the Contiguous United States (CONUS) is introduced here. These indices complement the catchment attributes provided earlier (Addor et al., 2017) for the CAMELS data set. The findings of the study revealed that the elevation, fraction of precipitation falling as snow and depth to bedrock mainly characterize the rising limb density, whereas the aridity and frequency of precipitation influence the rising limb scale parameter. Moreover, the rising limb shape parameter is primarily influenced by the forest fraction, the fraction of precipitation falling as snow, mean slope, mean elevation, sand fraction, and precipitation frequency. It is noted that falling limb density is mainly governed by climate indices, mean elevation, and the fraction of precipitation falling as snow; however, the recession coefficients are controlled by mean elevation, mean slope, clay, the fraction of precipitation falling as snow, forest fraction, and sand fraction.

Application of perforator propeller flap of lower limb in the treatment of foot and ankle defect in children

To investigate the effectiveness of perforator propeller flap of lower limb in the treatment of foot and ankle defect in children. The clinical data of 28 children with foot and ankle defect treated with perforator propeller flap of lower limb between January 2018 and January 2021 were retrospectively analyzed. There were 18 boys and 10 girls with an average age of 7.3 years (range, 6-14 years). There were 8 cases of traffic accident injury and 20 cases of chronic infection wound. The disease duration was 2-4 months, with an average of 2.8 months. After thorough debridement, the residual wound size ranged from 5 cm×4 cm to 9 cm×5 cm. Repairing was performed after 7-28 days of the infection in control. According to the location, size, and shape of the wound, the perforating vessels were located by ultrasonic Doppler, and the perforator propeller flap (area ranged from 6 cm×5 cm to 11 cm×6 cm) was designed and harvested to repair the wound. Flap transfer combined with free split-thickness skin graft covered the wound in 2 cases. The donor site was sutured directly (22 cases) or repaired with skin graft (6 cases). Twenty-six flaps survived, of which 20 cases were in primary healing, and 6 cases had epidermal necrosis at the end of small paddle, which healed after dressing change. Necrosis occurred in 2 cases due to venous crisis which healed after anterolateral femoral flap free transplantation. Primary wound healing was achieved in donor site. All 28 children were followed up 6-24 months (mean, 10.5 months). The texture, shape, and motor function of the lower limb was satisfactory. At last follow-up, the American Orthopaedic Foot and Ankle Association (AOFAS) score was 89.8±8.0, which was significantly different from the preoperative score (79.6±10.4) ( t=-11.205, P<0.001); 20 cases were excellent, 6 cases were good, and 2 cases were poor, and the excellent and good rate was 92.8%. The perforator propeller flap of lower limb in children has its own characteristics. It is a reliable method to repair the foot and ankle defect in children.

Visualizing the Unseen: Illustrating and Documenting Phantom Limb Sensations and Phantom Limb Pain With C.A.L.A.

Currently, there is neither a standardized mode for the documentation of phantom sensations and phantom limb pain, nor for their visualization as perceived by patients. We have therefore created a tool that allows for both, as well as for the quantification of the patient's visible and invisible body image. A first version provides the principal functions: (1) Adapting a 3D avatar for self-identification of the patient; (2) modeling the shape of the phantom limb; (3) adjusting the position of the phantom limb; (4) drawing pain and cramps directly onto the avatar; and (5) quantifying their respective intensities. Our tool (C.A.L.A.) was evaluated with 33 occupational therapists, physiotherapists, and other medical staff. Participants were presented with two cases in which the appearance and the position of the phantom had to be modeled and pain and cramps had to be drawn. The usability of the software was evaluated using the System Usability Scale and its functional range was evaluated using a self-developed questionnaire and semi-structured interview. In addition, our tool was evaluated on 22 patients with limb amputations. For each patient, body image as well as phantom sensation and pain were modeled to evaluate the software's functional scope. The accuracy of the created body image was evaluated using a self-developed questionnaire and semi-structured interview. Additionally, pain sensation was assessed using the SF-McGill Pain Questionnaire. The System Usability Scale reached a level of 81%, indicating high usability. Observing the participants, though, identified several operational difficulties. While the provided functions were considered useful by most participants, the semi-structured interviews revealed the need for an improved pain documentation component. In conclusion, our tool allows for an accurate visualization of phantom limbs and phantom limb sensations. It can be used as both a descriptive and quantitative documentation tool for analyzing and monitoring phantom limbs. Thus, it can help to bridge the gap between the therapist's conception and the patient's perception. Based on the collected requirements, an improved version with extended functionality will be developed.

The Regulation of Growth in Developing, Homeostatic, and Regenerating Tetrapod Limbs: A Minireview.

The size and shape of the tetrapod limb play central roles in their functionality and the overall physiology of the organism. In this minireview we will discuss observations on mutant animal models and humans, which show that the growth and final size of the limb is most impacted by factors that regulate either limb bud patterning or the elongation of the long bones. We will also apply the lessons that have been learned from embryos to how growth could be regulated in regenerating limb structures and outline the challenges that are unique to regenerating animals.

Impact of Prosthesis Fit on Nutritional Health of the Lower Limb Amputee

Socket designs ensure optimum fit between the user and the device (prosthesis), as an interface between the human – machine system. The type that an amputee is “fit with” depends on the shape of the residual limb, the length of the residual limb, activity level, prognosis, and individual preference. Patient satisfaction and function relies on pressure and force distribution (Biomechanics) on the socket-residual limb interface. The most determinant factor of prosthetic use lies in the design of the prosthetic socket and fit depends on the degree to which the prosthesis fits the stump. Well planned socket designs and careful consideration of stump presentation had set an achievement platform for the prosthetic user by maximizing range of motion, stability during the performance of daily activities, and comfortably distributing the forces exerted on the residual limb during movement and suspension. A study was conducted to analyze the health issues and their impact on the use/ acceptance of prosthesis among select amputees’. Physiological factors, obesity, age, nutritional status and co-morbidities were found to impose mechanical implications related to accessibility and well being concepts. The study highlighted prosthetic fitting to be more challenging with increased load (obesity) to transmit through the prosthetic socket in limited pressure–tolerant anatomical areas. Hence nutritional and physiotherapy intervention on effective and efficient prosthetic use was done to enhance their health and well -being.

A Computational Framework based on Medical Imaging and Random Sampling to Guide Optimal Residual Limb Designs for Individuals with Transfemoral Limb Loss.

The purpose of this study was to understand how the form (i.e., shape and presence of underlying soft tissue) of residual limb tissue influences limb function and comfort for individuals with transfemoral limb loss. Specifically, there exist surgical techniques that are frequently applied to the lower limbs of individuals to reduce an excessive soft tissue envelope. However, the clinical goals are frequently from a cosmetic perspective and are applied most commonly to individuals who are obese and not necessarily those with limb loss. For specific individuals with transfemoral limb loss, there likely exist limb shapes and distributions of underlying soft tissue that more optimally engage with lower-limb prostheses. Based on recent experimental findings, optimizing the limb and its physical connection to lower-limb prostheses, may have equivalent if not greater impact on user outcomes than selection of prosthetic components. This study develops and tests a method for informing optimal designs of the residual limb for individuals with transfemoral amputation. The framework uses patient-specific MRI images of an individual's residual limb, and within a mechanical modeling framework applies Latin hypercube sampling to investigate which portions of the underlying limb tissue most positively affect mechanical objectives associated with limb function and comfort. These theoretical results predicted from this system aimed to inform optimal limb designs were then compared to a currently used surgical method known as medial thighplasty, which was previously applied in one patient, to assess agreement. These simulations showed that the regions of the limb most contributing negatively to the objective function were located at the distal end of the limb and were far from muscle tissue (i.e., were mostly superficial). These findings suggest that limb techniques which seek to produce residual limbs that are most slim at their medial and distal end are beneficial and may lead to improved fit and function of lower-limb prostheses.Clinical Relevance-Prosthetic technology advancement within the last decade has heightened the hopes of individuals with amputation. However, how these devices integrate to their human users is non-trivial and can curtail these advancements. Tools are needed to inform how residual limb itself can be optimized to better integrate with prostheses.

Characterising Residual Limb Morphology and Prosthetic Socket Design Based on Expert Clinician Practice

Functional, comfortable prosthetic limbs depend on personalised sockets, currently designed using an iterative, expert-led process, which can be expensive and inconvenient. Computer-aided design and manufacturing (CAD/CAM) offers enhanced repeatability, but far more use could be made from clinicians’ extensive digital design records. Knowledge-based socket design using smart templates could collate successful design features and tailor them to a new patient. Based on 67 residual limb scans and corresponding sockets, this paper develops a method of objectively analysing personalised design approaches by expert prosthetists, using machine learning: principal component analysis (PCA) to extract key categories in anatomic and surgical variation, and k-means clustering to identify local ‘rectification’ design features. Rectification patterns representing Total Surface Bearing and Patella Tendon Bearing design philosophies are identified automatically by PCA, which reveals trends in socket design choice for different limb shapes that match clinical guidelines. Expert design practice is quantified by measuring the size of local rectifications identified by k-means clustering. Implementing smart templates based on these trends requires clinical assessment by prosthetists and does not substitute training. This study provides methods for population-based socket design analysis, and example data, which will support developments in CAD/CAM clinical practice and accuracy of biomechanics research.

Adjustable-Volume Prosthetic Sockets: Market Overview and Value Propositions.

The prosthetic socket is commonly considered to be the most important part of the prosthesis and lack of fit can lead to skin breakdown, reduction in wear, reduction in activity, and consequential deleterious health effects. Furthermore, approximately 90% of amputations are due to a vascular etiology, which affect fluid retention regularity, and even small limb volume fluctuations can lead to lack of fit. Adjustability in the socket volume has been suggested as a potential solution to common fit issues but has lacked market penetration mostly due to lack of reimbursement. Despite this there are several adjustable-volume sockets emerging on the market today including prefabricated, modular, custom with adjustable-volume component, custom with adjustable-volume feature, and adjustable-hybrid sockets. Prefabricated sockets are mass produced in common sizes and fit directly to the patient by a prosthetist using pad kits, BOA dials, or straps. Modular sockets are assembled to a patient or model with panels or struts attached to an adjustable base. Custom sockets with adjustable-volume elements are traditionally-fabricated sockets made to a model of a patient's limb with a volume-adjustable component added or volume-adjustable feature built in. Custom-hybrid sockets are made custom to a model of the patient's limb and incorporate several aspects of the previous socket types and include some radically-unique design aspects which cannot be limited to one category. These adjustable-volume sockets offer several advantages to traditional rigid-volume sockets for the patient, prosthetist, and providing clinic. The micro-adjustability for the patient allows them to alter fit without removing the socket, maintaining a more intimate fit throughout the day than traditional sockets. The macro-adjustability for the prosthetist allows for increased options for fit customization including the ability to reverse or undo changes without necessarily re-making the socket. This allows for the most optimal fit for the patient. Adjustable volume also present efficiencies in the fitting process by simplifying or eliminating steps including residual limb shape capture, form modification, diagnostic fabrication, iterative alteration, and definitive fabrication with the different socket types affecting different steps. Due to these factors, adjustable-volume sockets have disrupted the market to the point where reimbursement reform is needed including additional L-codes in the United States and fee-for-service or fee-for-outcome associated with prosthetic follow-up care. Prosthetic care should also be separated from durable medical equipment to allow for alternative reimbursement models. As reimbursement adapts prosthetists must adapt correspondingly to differentiate their skillset from other allied health providers including incorporating more objective methods to show superior care outcomes. This adaptation should include a continued push for state and municipal licensure of prosthetists.

Alligator appendicular architecture across an ontogenetic niche shift.

A variety of species undergo ontogenetic niche shifts in either diet, habitat, or both. As a result, multiple ontogenetic stages are able to take advantage of different resources and live in sympatry without competing with one another. The American alligator (Alligator mississippiensis) begins to undergo an ontogenetic niche shift in both diet and habitat at a length of 1.2m. They transition from a terrestrial wetland environment to a riverine environment and take advantage of different dietary resources. At 1.8m, A. mississippiensis reaches sexual maturity. Ontogenetic shifts in habitat have the capacity to alter morphology, especially limb morphology, as different age classes traverse different ecological systems. We evaluated shape trends in the scapulae, humeri, ilia, and femora using geometric morphometrics to test whether there were punctuated changes in limb shape, shape disparity, and integration corresponding to either the ontogenetic habitat shift or onset of sexual maturity. We found size to strongly correlate with limb shape but found a continuous size gradient rather than punctuated changes in size. Furthermore, we found that adults (total length > 1.8m) had significantly higher limb shape disparity than juveniles or subadults, likely related to ontogenetic decreases in limb use and a reduction in limb constraints. Finally, we found that the forelimb and hindlimb acted as a single integrated unit and that neither the forelimb nor hindlimb was significantly more integrated than the other. Therefore, the ontogenetic niche shift itself did not impact limb morphology in A. mississippiensis.

Thinking Inside the Box: Comparative Limb Bone Shape in Emydid Turtles

Limb bone morphology often correlates with functional demands placed on animals by the environment. Comparisons of limb bone allometry in functionally divergent turtle taxa indicate highly specialized lineages show extensive flattening of the humerus. In Sea Turtles this contributes to flipper-shaped forelimb morphology that facilitates lift-based swimming (i.e., underwater flight). In contrast robust humeri and femora in terrestrial tortoises may reflect specializations for resisting high torsional loads during terrestrial walking and digging. However, it is unknown whether allometric patterns of ecomorphological divergence can be detected among more closely related lineages within clades that encompass species with diverse ecological habits. To test whether limb bone size and shape vary among closely related taxa that live in divergent habitats, we used phylogenetic comparative methods to assess scaling patterns and overall morphology of the humerus and femur of 27 emydid turtle species representing four genera: Graptemys (semiaquatic), Pseudemys (semiaquatic), Trachemys (semiaquatic), and Terrapene (terrestrial). In general, we found that limb bones of emydid taxa scale isometrically for most length–diameter and length–mass relationships. However, terrestrial Terrapene (box turtles) species exhibit relatively short femora compared with species from the more aquatic genus Trachemys (sliders). The relatively small limb bones of box turtles may promote limb withdrawal into the shell, but without mechanical costs because of high safety factors of turtle limb bones. The comparatively robust forelimb and hindlimb dimensions of Graptemys (map turtles) relative to other emydid clades may reflect habitat and foraging pressures in this group.

Increased performance in juvenile baboons is consistent with ontogenetic changes in morphology.

In many primates, the greater proportion of climbing and suspensory behaviors in the juvenile repertoire likely necessitates good grasping capacities. Here, we tested whether very young individuals show near-maximal levels of grasping strength, and whether such an early onset of grasping performance could be explained by ontogenetic variability in the morphology of the limbs in baboons. We quantified a performance trait, hand pull strength, at the juvenile and adult stages in a cross-sectional sample of 15 olive baboons (Papio anubis). We also quantified bone dimensions (i.e., lengths, widths, and heights) of the fore- (n = 25) and hind limb (n = 21) elements based on osteological collections covering the whole development of olive baboons. One-year old individuals demonstrated very high pull strengths (i.e., 200% of the adult performance, relative to body mass), that are consistent with relatively wider phalanges and digit joints in juveniles. The mature proportions and shape of the forelimb elements appeared only at full adulthood (i.e., ≥4.5 years), whereas the mature hind limb proportions and shape were observed much earlier during development. These changes in limb performance and morphology across ontogeny may be explained with regard to behavioral transitions that olive baboons experience during their development. Our findings highlight the effect of infant clinging to mother, an often-neglected feature when discussing the origins of grasping in primates. The differences in growth patterns, we found between the forelimb and the hind limb further illustrate their different functional roles, having likely evolved under different ecological pressures (manipulation and locomotion, respectively).

Morphological factors extraction of upper limb for young female

This paper is proposed to extract the morphological factors of upper limb shapes related to the personalized sleeve design. The 36 items of lateral upper limb morphology were measured for 50 young female aged 19 to 22 years old by the photo measurement method. Based on the correlation relationships of morphological variables of upper limb, there are 4 morphological factors of upper limb shapes with eigenvalues above 1 were extracted by the principal component analysis, and the cumulative variance reached 83.504%. Among them, the factors of girth and height of upper limb were relevance to the girths of torso and stature respectively, and the factor of upper limb oblique angle is influenced by the upper body axis inclination, and the arm root height is interpreted as an independent factor describing the arm root shape. These morphological factors provided the references in key feature indicator sifting for upper limb shape subdivisions and the critical parameters in personalized sleeve structure designing.

Selecting Appropriate 3D Scanning Technologies for Prosthetic Socket Design and Transtibial Residual Limb Shape Characterization

ABSTRACTIntroductionPlaster casting and manual rectification represent the benchmark prosthetic socket design method. 3D technologies have increasing potential for prosthetic limb design and fabrication, especially for enhancing access to these services in low-resource settings. However, the community has a responsibility to verify the efficacy of these new digital technologies. The motivation for this study was to establish benchmarking data to assess digital shape capture technologies, specifically for clinically relevant residual limb shape and landmark capture for limb survey and socket design. The objective was therefore to assess the repeatability of plaster casting in vivo and to compare this with three clinically used 3D scanners.Materials and MethodsA comparative reliability assessment of casting and 3D scanning was conducted in 11 participants with established transtibial amputation. For each participant, two positive molds were cast by a prosthetist and digitized using a white-light 3D surface scanner. Between casts, each participant's residual limb was scanned. The deviation among scan volumes, cross-sections, and shapes was calculated.ResultsA total of 95% of the clinically relevant socket shape surface area had a deviation between manual casts of less than 2.87 mm (SD, 0.44 mm), and the average deviation was 0.18 mm (SD, 1.72 mm). The repeatability coefficient of casting was 46.1 ml (3.47%) for volume and 9.6 mm (3.53%) for perimeters. For all clinically meaningful measures, greater reliability was observed for the Omega scanner and worse for the Sense and iSense scanners, although it was observed that the Sense scanner performance was comparable to casting (95th percentile shape consistency).ConclusionsThis study provides a platform to appraise new clinical shape capture technologies in the context of best practice in manual plaster casting and starts the conversation of which 3D scanning devices are most appropriate for different types of clinical use. The methods and benchmark results may support prosthetists in acquiring and applying their clinical experience, as part of their continuing professional development.

Ontogenetic and morphological variation in primate long bones reflects signals of size and behavior.

Many primates change their locomotor behavior as they mature from infancy to adulthood. Here we investigate how long bone cross-sectional geometry in Pan, Gorilla, Pongo, Hylobatidae, and Macaca varies in shape and form over ontogeny, including whether specific diaphyseal cross sections exhibit signals of periosteal adaptation or canalization. Diaphyseal cross sections were analyzed in an ontogenetic series across infant, juvenile, and adult subgroups. Three-dimensional laser-scanned long bone models were sectioned at midshaft (50% of biomechanical length) and distally (20%) along the humerus and femur. Traditional axis ratios acted as indices of cross-sectional circularity, while geometric morphometric techniques were used to study cross-sectional allometry and ontogenetic trajectory. The humeral midshaft is a strong indicator of posture and locomotor profile in the sample across development, while the mid-femur appears more reflective of shifts in size. By comparison, the distal diaphyses of both limb elements are more ontogenetically constrained, where periosteal shape is largely static across development relative to size, irrespective of a given taxon's behavior or ecology. Primate limb shape is not only highly variable between taxa over development, but at discrete humeral and femoral diaphyseal locations. Overall, periosteal shape of the humeral and femoral midshaft cross sections closely reflects ontogenetic transitions in behavior and size, respectively, while distal shape in both bones appears more genetically constrained across intraspecific development, regardless of posture or size. These findings support prior research on tradeoffs between function and safety along the limbs.

&lt;p&gt;&lt;strong&gt;Floral geometric morphometrics unveils a new cauliflorous species of &lt;em&gt;Aristolochia&lt;/em&gt; (Aristolochiaceae) from the Guiana Shield&lt;/strong&gt;&lt;/p&gt;

Aristolochia wankeana (Aristolochiaceae), a new species from French Guiana and Guyana, is described and illustrated here. Floral traits, primarily of the shape and size of the perianth limb, examined through a morphometric geometric analysis, are diagnostic to distinguish the new species from its relatives A. cornuta and A. iquitensis. The species belongs to Aristolochia subser. Anthocaulicae, characterized by having extremely short cauliflorous racemes with scale-like, triangular subtending bracts. This is the first study that uses morphometrics for taxonomic purposes in Aristolochia, an approach that becomes promising to solve species complexes in this genus.

Appendicular skeletal morphology of North American Martes reflect independent modes of evolution in conjunction with Pleistocene glacial cycles.

Pleistocene glacial cycles are thought to have driven ecological niche shifts, including novel niche formation. North American pine martens, Martes americana and M. caurina, are exemplar taxa thought to have diverged molecularly and morphologically during Pleistocene glaciation. Previous research found correlations between Martes limb morphology with biome and climate, suggesting that appendicular evolution may have occurred via adaptation to selective pressures imposed by novel and shifting habitats. Such variation can also be achieved through non-adaptive means such as genetic drift. Here, we evaluate whether regional genetic differences reflect limb morphology differences among populations of M. americana and M. caurina by analyzing evolutionary tempo and mode of six limb elements. Our comparative phylogenetic models indicate that genetic structure predicts limb shape better than size. Marten limb size has low phylogenetic signal, and the best supported model of evolution is punctuational (kappa), with morphological and genetic divergence occurring simultaneously. Disparity through time analysis suggests that the tempo of limb evolution in Martes tracks Pleistocene glacial cycles, such that limb size may be responding to shifting climates rather than population genetic structure. Contrarily, we find that limb shape is strongly tied to genetic relationships, with high phylogenetic signal and a lambda mode of evolution. Overall, this pattern of limb size and shape variation may be the result of geographic isolation during Pleistocene glacial advance, while declines in disparity suggest hybridization during interglacial periods. Future inclusion of extinct populations of Martes, which were more morphologically and ecologically diverse, may further clarify Martes phenotypic evolution.

Regulation of the limb shape during the development of the Chinese softshell turtles.

Interdigital cell death is an important mechanism employed by amniotes to shape their limbs; inhibiting this process leads to the formation of webbed fingers, as seen in bats and ducks. The Chinese softshell turtle Pelodiscus sinensis (Reptilia: Testudines: Trionychidae) has a distinctive limb morphology: the anterior side of the limbs has partially webbed fingers with claw‐like protrusions, while the posterior fingers are completely enclosed in webbings. Here, P. sinensis embryos were investigated to gain insights on the evolution of limb‐shaping mechanisms in amniotes. We found cell death and cell senescence in their interdigital webbings. Spatial or temporal modulation of these processes were correlated with the appearance of indentations in the webbings, but not a complete regression of this tissue. No differences in interdigital cell proliferation were found. In subsequent stages, differential growth of the finger cartilages led to a major difference in limb shape. While no asymmetry in bone morphogenetic protein signaling was evident during interdigital cell death stages, some components of this pathway were expressed exclusively in the clawed digit tips, which also had earlier ossification. In addition, a delay and/or truncation in the chondrogenesis of the posterior digits was found in comparison with the anterior digits of P. sinensis, and also when compared with the previously published pattern of digit skeletogenesis of turtles without posterior webbings. In conclusion, modulation of cell death, as well as a heterochrony in digit chondrogenesis, may contribute to the formation of the unique limbs of the Chinese softshell turtles.

Multicategorical descriptors for creole genotypes of Amazon chicory (Eryngium foetidum)

ABSTRACT The knowledge concerning genetic variability of creole genotypes by using morphological descriptors in species such as Amazon chicory is crucial to quantify local diversity and protect improved cultivars. Accordingly, this study aimed to propose multicategory leaf morphological descriptors for Amazon chicory species. To achieve that, an experiment was arranged in randomized block design with four repetitions. The treatments comprised eight creole genotypes of Amazon chicory, which were obtained from local producers’ collection. The proposed multi-categorical descriptors are based on limb shape, leaf apex shape, leaf base shape, leaf margin, bract consistency, and bract margin traits. Once the multicategorical clustered data were obtained, they were transformed into a dissimilarity matrix. The limb shape presents dissimilarity, being either lanceolate or spatulate; as well as for leaf margin, which can be dentate or serrate. Thus, both limb shape and leaf margin constitute important qualitative descriptors for genetic diversity assessment and conservation for Amazon chicory, besides a recommended tool to be exploited in breeding programs.