Wing Shape Research Articles

Discrete and Continuous Adjoint-Based Aerostructural Wing Shape Optimization of a Business Jet

This article presents single- and multi-disciplinary shape optimizations of a generic business jet wing at two transonic cruise flow conditions. The studies performed are based on two high-fidelity gradient-based optimization tools, assisted by the adjoint method (following both discrete and continuous approaches). Single discipline and coupled multi-disciplinary sensitivity derivatives computed from the two tools are compared and verified against finite differences. The importance of not making the frozen turbulence assumption in adjoint-based optimization is demonstrated. Then, a number of optimization runs, ranging from a pure aerodynamic with a rigid structure to an aerostructural one exploring the trade-offs between the involved disciplines, are presented and discussed. The middle-ground scenario of optimizing the wing with aerodynamic criteria and, then, performing an aerostructural trimming is also investigated.

Quantitative analysis of the morphing wing mechanism of raptors: Bionic design of Falco Peregrinus wing skeleton.

The wing is one of the most important parts of a bird's locomotor system and is the inspiration origination for bionic wing design. During wing motions, the wing shape is closely related to the rotation angles of wing bones. Therefore, the research on the law of bone movement in the process of wing movement can be good guidance for the design of the bionic morphing wing. In this paper, the skeletal posture of the peregrine falcon wing during the extension/flexion is studied to obtain critical data on skeletal posture. Since an elbow joint and a wrist joint rotate correlatively to drive a wing to flex/extend, the wing skeleton is simplified as a four-bar mechanism in this paper. The degree of reproduction of wing skeleton postures was quantitatively analyzed using the four-bar mechanism model, and the bionic wing skeleton was designed. It is found that the wing motions have been reproduced with high precision.

Association between environmental gradient of anthropization and phenotypic plasticity in two species of triatomines

BackgroundTriatoma garciabesi and T. guasayana are considered secondary vectors of Trypanosoma cruzi and frequently invade rural houses in central Argentina. Wing and head structures determine the ability of triatomines to disperse. Environmental changes exert selective pressures on populations of both species, promoting changes in these structures that could have consequences for flight dispersal. The aim of this study was to investigate the relationship between a gradient of anthropization and phenotypic plasticity in flight-related traits.MethodsThe research was carried out in Cruz del Eje and Ischilín departments (Córdoba, Argentina) and included 423 individuals of the two species of triatomines. To measure the degree of anthropization, a thematic map was constructed using supervised classification, from which seven landscapes were selected, and nine landscape metrics were extracted and used in a hierarchical analysis. To determine the flight capacity and the invasion of dwellings at different levels of anthropization for both species, entomological indices were calculated. Digital images of the body, head and wings were used to measure linear and geometric morphometric variables related to flight dispersion. One-way ANOVA and canonical variate analysis (CVA) were used to analyze differences in size and shape between levels of anthropization. Procrustes variance of shape was calculated to analyze differences in phenotypic variation in heads and wings.ResultsHierarchical analysis was used to classify the landscapes into three levels of anthropization: high, intermediate and low. The dispersal index for both species yielded similar results across the anthropization gradient. However, in less anthropized landscapes, the density index was higher for T. garciabesi. Additionally, in highly anthropized landscapes, females and males of both species exhibited reduced numbers. Regarding phenotypic changes, the size of body, head and wings of T. garciabesi captured in the most anthropized landscapes was greater than for those captured in less anthropized landscapes. No differences in body size were observed in T. guasayana collected in the different landscapes. However, males from highly anthropized landscapes had smaller heads and wings than those captured in less anthropized landscapes. Both wing and head shapes varied between less and more anthropogenic environments in both species.ConclusionsResults of the study indicate that the flight-dispersal characteristics of T. garciabesi and T. guasayana changed in response to varying degrees of anthropization.Graphical

Two shell- and wing-shaped supernova remnants

Supernova remnants (SNRs) are profoundly affected by their ambient medium. In particular, SNRs with a mixed morphology (characterised by a shell-like radio morphology and centrally filled X-ray emission) are thought to be the result of the interaction of a supernova explosion with a dense environment. In this work, we present carbon monoxide (CO) observations around two mixed morphology SNRs, VRO 42.05.01 and G 350.0-2.0, that look remarkably similar in continuum radio emission, showing what we refer to as a shell and wing shape. It has been proposed that the shell and wing shape is the result of environmental effects, in the form of a sharp density gradient or discontinuity. Therefore, our motivation for studying these two sources jointly is that if the dense molecular environment causes the development of these sources’ shell and wing shape, then these two sources’ environments must be similar. This is contrary to what we observe. In the case of VRO 42.05.01, we have found direct evidence of an interaction with its molecular environment, in the form of broadened 12CO line profiles, high 12CO (J = 2−1) to 12CO (J = 1−0) line ratios, and arc features in position-velocity space. We interpret some of these features to be associated with the SNR shock, and some of them to be due to the presence of a pre-supernova stellar wind. We have found no such features in the abundant molecular gas surrounding G 350.02.0. In addition to the spectral line analysis, we have used radio continuum data to make a spectral index map of G 350.0-2.0, and we see that the radio spectrum of G 350.0-2.0 steepens significantly at frequencies <200 MHz, much like that of VRO 42.05.01. In spite of their spectral and morphological similarities, these two sources look substantially different in their observed optical and infrared emission. The lack of large-scale correspondence between the radio continuum and the molecular material, in either case, as well as the differences in the excitation and morphological properties of the molecular gas surrounding both sources, lead us to conclude that the shell and wing morphology of these two sources is not due to interactions with a similar ambient molecular interstellar medium.

Association of Left Atrial Appendage Morphology and Function With Stroke and Transient Ischemic Attack in Atrial Fibrillation Patients

We aimed to correlate left atrial appendage (LAA) structure and function with the history of stroke/transient ischemic attack (TIA) in patients with atrial fibrillation (AF). We analyzed data of 649 patients with AF who were scheduled for catheter ablation. Patients underwent cardiac CT and transesophageal echocardiography prior to ablation. LAA morphologies depicted by cardiac CT were categorized into four groups: cauliflower, chicken wing, swan and windsock shapes. Mean age was 61.3±10.5 years, 33.9% were female. Prevalence of stroke/TIA was 7.1%. After adjustment for the main risk factors, LAA flow velocity ≤35.3 cm/sec (OR=2.18; 95%CI=1.09-4.61; p=0.033) and swan LAA shape (OR=2.69; 95%CI=0.96-6.86; p=0.047) independently associated with higher risk of stroke/TIA, while windsock LAA morphology proved to be protective (OR=0.32; 95%CI=0.12-0.77; p=0.017) as compared to cauliflower LAA shape. When comparing the differences between LAA morphology groups, we measured significantly smaller LAA orifice area (389.3±137.7 mm2 in windsock vs 428.3±158.9 ml in cauliflower, p=0.021) and LAA volume (7.4±3.0 mm2 in windsock vs 8.5±4.8 mm2 in cauliflower, p=0.012) in patients with windsock LAA morphology, while LAA flow velocity did not differ significantly. Reduced LAA function and swan LAA morphology were independently associated with higher prevalence of stroke/TIA, while windsock LAA shape proved to be protective. When comparing the differences between the various LAA morphology types, significantly lower LAA volume and LAA orifice area were measured in windsock LAA shape as compared to cauliflower LAA shape.

Environmental dynamics and seasonal wing physiological changes of coastal mosquito vectors (Diptera: Culicidae) in Central Thailand

Mosquitoes (Diptera: Culicidae) are small hematophagous insects that serve as disease vectors by transmitting pathogens to humans and animals. This study was conducted on the coastline of Samut Songkhram Province in Thailand's central region to evaluate the impact of environmental factors on coastal mosquitoes, namely Anopheles epiroticus and Culex sitiens. A zero-inflated negative binomial (ZINB) regression was employed to assess the relationship between the density of larval mosquitoes and water quality factors. Spearman's rank correlation was used to examine the relationship between the number of adult mosquitoes and meteorological factors, and the geometric morphometric (GM) technique was used to study the wing size and shape of adult mosquitoes throughout different seasons. The ZINB analysis revealed a significant negative relationship (p < 0.05) between dissolved oxygen, high-range phosphate, and the number of An. epiroticus larvae. Conversely, in the case of Cx. sitiens, there was a significant positive relationship between nitrate-nitrogen and larval density (p < 0.01), while dissolved oxygen exhibited a significant negative relationship (p < 0.05). Regarding adult mosquitoes, relative humidity was positively correlated with the abundance of adult Cx. sitiens (r = 0.85, p < 0.01), whereas each meteorological parameter—temperature, relative humidity, rainfall, wind speed, and atmospheric pressure—was negatively correlated with adult An. epiroticus abundance (p < 0.05 for each). The GM analysis revealed statistically significant seasonal variations in wing shapes for both species (p < 0.05 for all seasonal comparisons), underscoring their adaptation to seasonal environmental conditions in coastal habitats.

Deep learning reduces sensor requirements for gust rejection on a small uncrewed aerial vehicle morphing wing

Uncrewed aerial vehicles are integral to a smart city framework, but the dynamic environments above and within urban settings are dangerous for autonomous flight. Wind gusts caused by the uneven landscape jeopardize safe and effective aircraft operation. Birds rapidly reject gusts by changing their wing shape, but current gust alleviation methods for aircraft still use discrete control surfaces. Additionally, modern gust alleviation controllers challenge small uncrewed aerial vehicle power constraints by relying on extensive sensing networks and computationally expensive modeling. Here we show end-to-end deep reinforcement learning forgoing state inference to efficiently alleviate gusts on a smart material camber-morphing wing. In a series of wind tunnel gust experiments at the University of Michigan, trained controllers reduced gust impact by 84% from on-board pressure signals. Notably, gust alleviation using signals from only three pressure taps was statistically indistinguishable from using six pressure tap signals. By efficiently rejecting environmental perturbations, reduced-sensor fly-by-feel controllers open the door to small uncrewed aerial vehicle missions in cities.

Methodology for Evaluating a Distributed Variable-Camber Trailing-Edge System in Preliminary Aircraft Design

A controlled adjustment of the wing camber during cruise flight by an extension of each separate flap allows for wing shape optimization, depending on the current mission point including the prevailing conditions, contributing to an increase in efficiency. This is referred to as variable camber (VC). This paper aims to investigate a methodology for a retrofit application of VC technology with differential flap setting, especially for a segmented trailing-edge system at the overall aircraft level in the preliminary design phase. In addition, an assessment is conducted to clarify whether actuation on the basis of a central shaft system or a decentralized power-by-wire system is advantageous. The investigation is based on a commercial aircraft with a maximum takeoff mass of 270 t and compares the potential of a VC application with an aerostructural twist optimization of the wing. Different configurations of the trailing-edge flaps, ranging from a common two-flap configuration up to a configuration with six trailing-edge devices, are covered in order to give a holistic implementation recommendation, including actuation and flap segmentation. Depending on the reference aircraft, the study shows a considerable fuel-saving potential for VC applications, e.g., 3.5% for the pre-optimized reference on a long-range mission.

Evolution of wing shape in geometrid moths: phylogenetic effects dominate over ecology.

Locomotory performance is an important determinant of fitness in most animals, including flying insects. Strong selective pressures on wing morphology are therefore expected. Previous studies on wing shape in Lepidoptera have found some support for hypotheses relating wing shape to environment-specific selective pressures on aerodynamic performance. Here, we present a phylogenetic comparative study on wing shape in the lepidopteran family Geometridae, covering 374 species of the northern European fauna. We focused on 11 wing traits including aspect ratio, wing roundness, and the pointedness of the apex, as well as the ratio of forewing and hindwing areas. All measures were taken from images available on the internet, using a combination of tools available in Fiji software and R. We found that wing shape demonstrates a phylogenetically conservative pattern of evolution in Geometridae, showing similar or stronger phylogenetic signal than many of its potential predictors. Several wing traits showed statistically significant associations with predictors such as body size, phenology, and preference for forest habitats. Overall, however, all of these associations remained notably weak, with no wing shape being excluded for any value of the predictors, including body size. We conclude that, in geometrids, wing traits do not readily respond to selective pressures optimizing aerodynamic performance of the moths in different environments. Selection on wing shape may nevertheless operate through other functions of the wings, with the effectiveness of crypsis at rest being a promising candidate for further studies.

Study on the characteristics of increased mechanical stiffness according to changes in LCP shape to reinforce clavicle fractures

The clavicle has various anatomic shapes unique to each individual. Additionally, with the increase in high-energy traumas such as sports injuries and traffic accidents, the patterns of fractures become complex and complicated. Thus, there is a need for a variety of shapes of locking compression plates (LCP) to accommodate different types of fractures and facilitate quicker rehabilitation. The aim of this study is to present different types of LCP that secure fracture fragments and distribute stress evenly, in comparison to typical anatomical LCPs, for reinforcing clavicle fractures. Three models were compared in this study: the typical shape, the center hole removed shape, and the double-curved wing shape. The DICOM (Digital Imaging and Communications in Medicine) file obtained from the computed tomography scan of the patient’s clavicle was used to extract the three-dimensional (3D) clavicle structure. Finite element analysis (FEA) simulation was employed to analyze the structural changes of the LCP under external forces. A reinforced jig was used to apply the same type of external force to each LCP, and an experiment was conducted to analyze the mechanical impact of the LCP’s structural characteristics. When comparing the stress values at the fracture zone point, resulting from the FEA simulation with applied bending forces, it was calculated that the stress dispersion effect was approximately ten times greater when transitioning from a typical LCP shape to a double-curved partial wing structure. Moreover, the ultimate stress increased 3.33 times, from 241.322 to 804.057 N, as the LCP design changed under cantilever bending conditions. This double-curved wing LCP design reduces stress concentration at the fracture site and minimizes stress in the fracture area when subjected to cantilever bending forces. Consequently, this newly designed LCP has the potential to decrease complications related to the plate and accelerate rehabilitation protocols.

Population genetic structure and wing geometric morphometrics of the filarial vector Armigeres subalbatus (Diptera: Culicidae) in Thailand

Armigeres subalbatus (Diptera: Culicidae) is a mosquito species of significant medical and veterinary importance. It is widely distributed across Southeast and East Asia and is commonly found throughout Thailand. This study assessed the genetic diversity and population structure of Ar. subalbatus in Thailand using the cytochrome c oxidase subunit I (COI) gene sequences. Additionally, wing shape variations among these populations were examined using geometric morphometrics (GM). Our results demonstrated that the overall haplotype diversity (Hd) was 0.634, and the nucleotide diversity (π) was 0.0019. Significant negative values in neutrality tests (p < 0.05) indicate that the Ar. subalbatus populations in Thailand are undergoing a phase of expansion following a bottleneck event. The mismatch distribution test suggests that the populations may have started expanding approximately 16,678 years ago. Pairwise genetic differentiation among the 12 populations based on Fst revealed significant differences in 32 pairs (p < 0.05), with the degree of differentiation ranging from 0.000 to 0.419. The GM analysis of wing shape also indicated significant differences in nearly all pairs (p < 0.05), except for between populations from Nakhon Pathom and Samut Songkhram, and between those from Chiang Mai and Mae Hong Son, suggesting no significant difference due to their similar environmental settings. These findings enhance our understanding of the population structure and phenotypic adaptations of mosquito vectors, providing vital insights for the formulation of more efficacious vector control strategies.

Insights into the mitochondrial cytochrome oxidase I (mt-COI) gene and wing morphometrics of Anopheles baimaii (Diptera: Culicidae) in malaria-endemic islands of Thailand.

Anopheles baimaii (Diptera: Culicidae) significantly contributes to the transmission of parasites causing malaria in Southeast Asia and South Asia. This study examined the morphological (wing shape) and molecular (mitochondrial gene) variations of An. baimaii in four of Thailand's border islands, and also investigated the presence of Plasmodium parasites in these mosquitoes. No Plasmodium infections were detected in the samples. Significant differences in wing shape were observed in most island populations (p < 0.05). A single-linkage tree, constructed using Mahalanobis distances, clustered the populations into two groups based on geographical locations. Genetic variation in An. baimaii was also analyzed through cytochrome c oxidase subunit I (COI) gene sequences. This analysis identified 22 segregating sites and a low nucleotide diversity of 0.004. Furthermore, 18 distinct haplotypes were identified, indicating a high haplotype diversity of 0.825. Neutrality tests for the overall population revealed a significantly negative Fu's Fs value (-5.029), indicating a population expansion. In contrast, Tajima's D yielded a negative value (-1.028) that did not reach statistical significance. The mismatch distribution analysis exhibited a bimodal pattern, and the raggedness index was 0.068, showing no significant discrepancy (p = 0.485) between observed and expected distributions. Pairwise genetic differentiation assessments demonstrated significant differences between all populations (p < 0.05). These findings provide valuable insights into the COI gene and wing morphometric variations in An. baimaii across Thailand's islands, offering critical information for understanding the adaptations of this malaria vector and guiding future comprehensive research.

Automated shape and thickness optimization for non-matching isogeometric shells using free-form deformation

AbstractIsogeometric analysis (IGA) has emerged as a promising approach in the field of structural optimization, benefiting from the seamless integration between the computer-aided design (CAD) geometry and the analysis model by employing non-uniform rational B-splines (NURBS) as basis functions. However, structural optimization for real-world CAD geometries consisting of multiple non-matching NURBS patches remains a challenging task. In this work, we propose a unified formulation for shape and thickness optimization of separately parametrized shell structures by adopting the free-form deformation (FFD) technique, so that continuity with respect to design variables is preserved at patch intersections during optimization. Shell patches are modeled with isogeometric Kirchhoff–Love theory and coupled using a penalty-based method in the analysis. We use Lagrange extraction to link the control points associated with the B-spline FFD block and shell patches, and we perform IGA using the same extraction matrices by taking advantage of existing finite element assembly procedures in the FEniCS partial differential equation (PDE) solution library. Moreover, we enable automated analytical derivative computation by leveraging advanced code generation in FEniCS, thereby facilitating efficient gradient-based optimization algorithms. The framework is validated using a collection of benchmark problems, demonstrating its applications to shape and thickness optimization of aircraft wings with complex shell layouts.

Dispersal constrains the biotic connectivity of mountain assemblages

AbstractAimClimate warming is shifting the bioclimatic optima of species towards mountaintops, but the ability of organisms to track these changes also depends on their dispersal skills. Here, we assessed the role of dispersal over niche‐driven processes in connecting assemblages along mountain slopes and between mountain massifs.LocationCantabrian Mountains, Spain.TaxonBirds (Animalia; Aves) and Lichens (Fungi; Ascomycota, Basidiomycota).MethodsWe examined the change with elevation of community‐level traits that are dispersal proxies (wing shape in birds and type of dispersing propagule in lichens) and ecological niche proxies (micro‐habitat, substrate, and foraging features). We then permutate species composition within sites and massifs to create models of species distribution constrained by dispersal and niche processes. These models were compared with observed species distribution to disclose the relative contribution of dispersal and niche‐based processes in the biotic interchange along mountain slopes (vertical connectivity) and between isolated summits (horizontal connectivity).ResultsBoth bird and lichen communities were formed by species with traits that enhance dispersal at high elevations. These groups also showed similarities in the elevational patterns of niche diversity, which dropped at high elevations. Dispersal was by far the dominant assembly mechanism in both taxa. Pairwise community comparisons among elevation belts showed weak vertical connectivity, with predominant dispersal limitations but also niche barriers between the extremes of the gradient. Among massifs, horizontal connectivity was higher among high mountain assemblages than those from lower elevations.Main ConclusionDispersal was found to be the dominant assembly mechanism in mountain systems, even in taxa with high dispersal potential. Highland assemblages had low functional diversity but their species had high mobility. This permits biotic interchange between isolated summits and, potentially, colonization of other summits as climate warms. Our framework combining traits and occurrence‐permutation models improve the understanding of community assembly mechanisms along elevation gradients and points to dispersal limitations, especially at low‐middle elevations.

Flight Dispersal in Supratidal Rockpool Beetles.

Flight dispersal is ecologically relevant for the survival of supratidal rockpool insects. Dispersal has important consequences for colonisation, gene flow, and evolutionary divergence. Here, we compared the flight dispersal capacity of two congeneric beetle species (Ochthebius quadricollis and Ochthebius lejolisii) that exclusively inhabit these temporary, fragmented, and extreme habitats. We estimated flight capacity and inferred dispersal in both species using different approaches: experimental flying assays, examination of wing morphology, and comparison of microsatellite markers between species. Our findings revealed that both species exhibited similar flight behaviour, with 60 to 80% of the individuals flying under water heating conditions. Notably, females of both species had larger body sizes and wing areas, along with lower wing loading, than males in O. quadricollis. These morphological traits are related to higher dispersal capacity and more energetically efficient flight, which could indicate a female-biassed dispersal pattern. The wing shapes of both species are characterised by relatively larger and narrower wings in relation to other species of the genus, suggesting high flight capacity at short distances. Molecular data revealed in both species low genetic divergences between neighbouring populations, non-significant differences between species, and no isolation by distance effect at the study scale (<100 km). These results point to passive dispersal assisted by wind.

Phylogeography and phenotypic wing shape variation in a damselfly across populations in Europe.

Describing geographical variation in morphology of organisms in combination with data on genetic differentiation and biogeography can provide important information on how natural selection shapes such variation. Here we study genetic structure using ddRAD seq and wing shape variation using geometric morphometrics in 14 populations of the damselfly Lestes sponsa along its latitudinal range in Europe. The genetic analysis showed a significant, yet relatively weak population structure with high genetic heterozygosity and low inbreeding coefficients, indicating that neutral processes contributed very little to the observed wing shape differences. The genetic analysis also showed that some regions of the genome (about 10%) are putatively shaped by selection. The phylogenetic analysis showed that the Spanish and French populations were the ancestral ones with northern Swedish and Finnish populations being the most derived ones. We found that wing shape differed significantly among populations and showed a significant quadratic (but weak) relationship with latitude. This latitudinal relationship was largely attributed to allometric effects of wing size, but non-allometric variation also explained a portion of this relationship. However, wing shape showed no phylogenetic signal suggesting that lineage-specific variation did not contribute to the variation along the latitudinal gradient. In contrast, wing size, which is correlated with body size in L. sponsa, had a strong negative correlation with latitude. Our results suggest a relatively weak population structure among the sampled populations across Europe, but a clear differentiation between south and north populations. The observed geographic phenotypic variation in wing shape may have been affected by different local selection pressures or environmental effects.

The Extraordinary Diversity of Merodon avidus Complex (Diptera: Syrphidae)-Adding New Areas, New Species and a New Molecular Marker.

In this paper, the Merodon avidus (Diptera, Syrphidae) species complex was revised, whereupon we discovered and described four new species for science: Merodon atroavidus Vujić, Radenković et Likov sp. nov., M. magnus Vujić, Kočiš Tubić et Ačanski sp. nov., M. nigroscutum Vujić, Radenković et Likov sp. nov. and M. pseudomoenium Vujić, Kočiš Tubić et Ačanski sp. nov. An integrative taxonomy approach was used to delimit species boundaries. Two molecular markers (the mitochondrial COI gene and nuclear 28S rRNA gene-newly analysed marker for the complex) and geometric morphometry of the wing shape, together with morphological data and distribution, successfully separated all species from the complex. The morphological variability of the analysed species is described and discussed and an illustrated diagnostic key for typical morpho-forms of species from the M. avidus complex is presented. A distribution map of all investigated species from the complex is provided. The level of endemicity of the M. avidus complex was discussed.

Differential expression of antimicrobial peptide encoding genes of honey bee (Apis mellifera) after Varroa mite (Varroa destructor) infestation

Varroa destructor mite is a serious threat to the world apiculture industry, and severely hampered beekeeping practices. Innate immune systems are key defenses of animals and are particularly important in species that lack the sophisticated adaptive immune systems found in vertebrates. In honey bees, antimicrobial immune peptide genes play a significant immune response against pathogens. The present study analyzed the detrimental effects of Varroa infestation on Apis mellifera at all developmental stages in both Varroa challenged and controlled hives. Physical attributes were observed in Varroa hives at different time intervals (0, 30, and 45 days respectively). After 45 days of Varroa exposure, the samples were taken, and the AMPs immune response of bees parasitized by Varroa was detected by studying the expression levels of antibacterial peptides (defensin, apidaecin, abaecin, and hymenoptaecin). Significant alterations in the physical parameters viz. body length, body weight, wing shape, and mean numbers of brood cells were observed compared to the control. Colony density was also decreased with marked negative behavioural changes. Ct values of Real-Time PCR results showed that AMP-specific immune gene transcription level in Varroa-challenged bees was downregulated, except for abaecin and defensin (adult stage). There was a significant (p < 0.05) increase in abaecin gene transcription folds i.e., 1.064 larvae, 1.732 pupae, and 1.264 adults bees. As a whole, all these findings can be taken as critical biomarkers in the advancement of control techniques against Varroa and other pathogen infections as a part of wide-ranging programs of honey bee health and Varroa control.

Influence of posture during gliding flight in the flying lizard Draco volans

The agamid lizards of the genus Draco are undoubtedly the most renown reptilian gliders, using their rib-supported patagial wings as lifting surfaces while airborne. Recent investigations into these reptiles highlighted the role of body posture during gliding, however, the aerodynamics of postural changes in Draco remain unclear. Here, we examine the aerodynamics and gliding performances of Draco volans using a numerical approach focusing on three postural changes: wing expansion, body camber, and limb positioning. To this aim, we conducted 70 three-dimensional steady-state computational fluid dynamics simulations of gliding flight and 240 two-dimensional glide trajectory calculations. Our results demonstrate that while airborne, D. volans generates a separated turbulent boundary layer over its wings characterized by a large recirculation cell that is kept attached to the wing surface by interaction with wing–tip vortices, increasing lift generation. This lift generating mechanism may be controlled by changing wing expansion and shape to modulate the generation of aerodynamic force. Furthermore, our trajectory simulations highlight the influence of body camber and orientation on glide range. This sheds light on how D. volans controls its gliding performance, and conforms to the observation that these animals plan their glide paths prior to take off. Lastly, D. volans is mostly neutral in pitch and highly maneuverable, similar to other vertebrate gliders. The numerical study presented here thus provides a better understanding of the lift generating mechanism and the influence of postural changes in flight in this emblematic animal and will facilitate the study of gliding flight in analogous gliding reptiles for which direct observations are unavailable.

Geometric morphometrics of the wings of Amazonian species of Melipona (Illiger, 1806) (Hymenoptera: Apidae).

Identifying and classifying species of stingless Neotropical bees is not a trivial task and requires the help of taxonomists and substantial study and training time. Also, there is a lack of taxonomically useful characters to differentiate among the megadiverse Neotropical group of stingless bees, and to recognize variation. Based on that, we have been testing alternatives to a character-based, efficient taxonomic determination of stingless bees, and herein we performed exploratory analyses of wing shape variation using geometric morphometrics. Thus, we built a data set of photographs of the right anterior wing of 1628 individuals belonging to 11 species in the genus Melipona (Illiger 1806) taken from collection material deposited in entomological collections. We then conducted a Procrustes analysis, followed by a Principal Component Analysis (PCA) and by a Canonical Variable Analyses (CVA). The two first principal components of the PCA accounted for 68% of the variation of the wing shape, and the ordination displayed by the first component separated species of the subgenus Melikerria from the others. In the CVA, the first two canonical axes explained 88% of the wing shape variation found among species, and Melikerria appears as a separate group, apart from the other subgenera in the first canonical axis. Along the second axis species belonging to Eomelipona and Michmelia, and among the Michmelia species, and its species group fuliginosa formed well-separated clusters. The wing shape variation of Melipona supports the recognition of subgenera as currently proposed for Melipona.