Wings’ Descriptive and Geometric Morphometry Analyses Support Distinct Phlebotomus sergenti Parrot Populations in Central Morocco

Phlebotomus (Paraphlebotomus) sergenti Parrot, 1917, the proven vector of Leishmania tropica Wright, 1903, the causative agent of anthroponotic cutaneous leishmaniasis, is widely distributed in Morocco. Previous works using molecular markers (ITS2 rDNA and Cyt b mtDNA) have hy-pothesized the existence of multiple closely related populations of sandfly species (cryptic species) that would exhibit distinct vectorial capacities. In this work, descriptive characteristics of wings (size and shape of the right and left wings) were measured in samples collected from fourteen sta-tions in central Morocco. These analyses support the existence of distinct P. sergenti populations, enlightening significant phenotypic variations of P. sergenti’s wings, regarding their size and shape, depending on geographic origin. In addition, geomorphometric analyses of wing’s length, centroid size, alpha, and beta distances allowed clear discrimination of P. sergenti sub-populations. These data pinpoint the adaptative ability of P. sergenti to local environmental conditions. Additional studies are now required to further shed light on the genetic structure of P. sergenti populations in Morocco.

Automatic 3D dense phenotyping provides reliable and accurate shape quantification of the human mandible

Automatic craniomaxillofacial (CMF) three dimensional (3D) dense phenotyping promises quantification of the complete CMF shape compared to the limiting use of sparse landmarks in classical phenotyping. This study assesses the accuracy and reliability of this new approach on the human mandible. Classic and automatic phenotyping techniques were applied on 30 unaltered and 20 operated human mandibles. Seven observers indicated 26 anatomical landmarks on each mandible three times. All mandibles were subjected to three rounds of automatic phenotyping using Meshmonk. The toolbox performed non-rigid surface registration of a template mandibular mesh consisting of 17,415 quasi landmarks on each target mandible and the quasi landmarks corresponding to the 26 anatomical locations of interest were identified. Repeated-measures reliability was assessed using root mean square (RMS) distances of repeated landmark indications to their centroid. Automatic phenotyping showed very low RMS distances confirming excellent repeated-measures reliability. The average Euclidean distance between manual and corresponding automatic landmarks was 1.40 mm for the unaltered and 1.76 mm for the operated sample. Centroid sizes from the automatic and manual shape configurations were highly similar with intraclass correlation coefficients (ICC) of > 0.99. Reproducibility coefficients for centroid size were < 2 mm, accounting for < 1% of the total variability of the centroid size of the mandibles in this sample. ICC’s for the multivariate set of 325 interlandmark distances were all > 0.90 indicating again high similarity between shapes quantified by classic or automatic phenotyping. Combined, these findings established high accuracy and repeated-measures reliability of the automatic approach. 3D dense CMF phenotyping of the human mandible using the Meshmonk toolbox introduces a novel improvement in quantifying CMF shape.

Divergent morphological responses to millennia of climate change in two species of bats from Hall’s Cave, Texas, USA

How species will respond to ongoing and future climate change is one of the most important questions facing biodiversity scientists today. The fossil record provides unparalleled insight into past ecological and evolutionary responses to climate change, but the resource remains virtually untapped for many organisms. We use geometric morphometrics and a 25,000 year fossil record to quantify changes in body size and mandible shape through time and across climate regimes for two bat species present in Quaternary paleontological deposits of central Texas: Myotis velifer, a bat distributed throughout the Southwestern US and Mexico that is still found in central Texas today, and Eptesicus fuscus, a bat widely distributed throughout North America that has been extirpated in central Texas. Because of ecogeographic rules like Bergmann’s rule, which posits that endotherms are larger in colder environments, we hypothesized that both species were larger during cooler time intervals. Additionally, we hypothesized that both species would show variation in dental morphology across the studied sequence as a response to climate change. While we found a decrease in centroid size–a proxy for ­­body size–through time for both species, we could not establish a clear relationship between centroid size and temperature alone. However, we did find that specimens from drier environments were significantly larger than those from wetter ones. Furthermore, we found significant dental shape variation between environments reflecting different temperature levels for both species. Yet only M. velifer exhibited significant variation between environments of varying precipitation levels. This result was surprising because present-day populations of E. fuscus are highly variable across both temperature and precipitation gradients. We determined that the morphological change experienced by M. velifer through time, and between warmer and cooler temperatures, was associated with the coronoid process, condylar process, and the mandibular symphysis. These parts play a pivotal role in bite force, so changes in these features might relate to changes in diet. We show that long-term datasets derived from fossil material provide invaluable insight not only into the validity of ecogeographic rules, but also into the adaptive capacities of extant taxa when faced with environmental changes. Our results highlight diverging responses to a variety of climate factors that are relevant to consider in biodiversity research given ongoing global change.

Diversity and Geographical Distribution of Sand Flies Phlebotomus papatasi (Diptera: Phlebotominae) by using Geometric Morphometric Technique from two Iraqi Provinces

The variation in wing morphological features was investigated using geometric morphometric technique of the Sand Fly from two Iraqi provinces Babylon and Diyala . We distributed eleven landmarks on the wings of Sand Fly species. By using the centroid size and shape together, all species were clearly distinguished. It is clear from these results that the wing analysis is an essential method for future geometric morphometry studies to distinguish the species of Sand Flies in Iraq.

Morphometric Differentiation and Diet of Engystomops pustulosus (Amphibia: Leptodactylidae) in Three Populations from Colombia

This paper evaluated the intraspecific variation and diet of Engystomops pustulosus in three localities (Colosó, Santa Inés, and El Roble) of the department of Sucre, Colombia. Thirty specimens were collected by locality and the diet composition was determined. We characterized the phenotypic variation by means of skull geometric morphometrics and ten body measures. Finally, the relationship between morphogeometric variables (shape and size) and diet were evaluated. We found significant differences between skull conformation and localities, and between localities and the centroid size. Termites were the most important type of prey, followed by ants and mites. The diet composition did not correlate with the body measures; however, an analysis of Partial Least-Squares showed a correlation between the composition of the diet and skull conformation.

Influence of mass on tarsus shape variation: a morphometrical investigation among Rhinocerotidae (Mammalia: Perissodactyla)

Many tetrapod lineages show extreme increases in body mass in their evolutionary history, associated with important osteological changes. The ankle joint, essential for foot movement, is assumed to be particularly affected in this regard. We investigated the morphological adaptations of the astragalus and the calcaneus in Rhinocerotidae, and analysed them in light of a comparative analysis with other Perissodactyla. We performed 3D geometric morphometrics and correlated shape with centroid size of the bone and body mass of the species. Our results show that mass has an influence on bone shape in Rhinocerotidae and in Perissodactyla, but this is not as strong as expected. In heavy animals the astragalus has a flatter trochlea, orientated more proximally, associated with a more upright posture of the limb. The calcaneus is more robust, possibly to sustain the greater tension force exerted by the muscles during plantarflexion. Both bones show wider articular facets, providing greater cohesion and better dissipation of the loading forces. The body plan of the animals also has an influence. Short-legged Teleoceratina have a flatter astragalus than the other rhinocerotids. Paraceratherium has a thinner calcaneus than expected. This study clarifies adaptations to high body weight among Rhinocerotidae and calls for similar investigations in other groups with massive forms.

Adolescent dental arch development among Southern Chinese in Hong Kong: a geometric morphometric approach

This study aimed to investigate changes in types of dental arch form during adolescence and explore adolescent changes in size and form of dental arch. Hong Kong Chinese were recruited and digital dental arch models were obtained at ages 12, 15, and 18 years. Geometric morphometrics was used to investigate adolescent changes of dental arch form. There were 225 participants from whom digital models at all three age periods were available. Three types of dental arch form were identified through clustering. Significant changes (p < 0.001) in types of dental arch form were noted during age 12–18 years. During age 12–18 years, significant changes in centroid size and form of dental arch were observed (p < 0.001). No significant changes were observed during 15–18 years. Adolescent changes of dental arch form occur primarily during age 12–15 years, whereas dental arch form was relatively stable during age 15–18 years.

Sexual dimorphism in Belostoma angustum Lauck (Insecta: Heteroptera: Belostomatidae) may be related to paternal care

The structures involved in parental care are often dimorphic. Female Belostoma angustum water bugs lay eggs on the hemelytra of their mates, where the eggs are brooded until hatching. Males use their hind legs to carry, aerate and protect the eggs. After controlling for covariance between variables, we fitted a series of structural equation models (SEMs) and evaluated the existence of sexual dimorphism in the size of the body and hind legs, in the shape and centroid size of the hemelytrum, and among the static allometry slopes of the size-related differences. Landmarks were used to capture phenotypic variation, by eliminating all non-shape variations with a Procrustes superimposition. Neither the shape of the hemelytrum nor its centroid size was related significantly to the aforementioned linear body measurements. Instead, the differences in the size of the hind legs were mediated by body dimensions only in males. We also found that males were wider and had longer heads than females, according to the SEM intercept values. Our findings suggest that sexual dimorphism in B. angustum may be related to a balance between sexual role reversal and viability costs.

Chrysomya megacephala (Fabricius, 1794) (Diptera: Calliphoridae) development by landmark-based geometric morphometrics of cephalopharyngeal skeleton: a preliminary assessment for forensic entomology application

Background Considering the practicality of geometric morphometrics which could discriminate insect species, this application was extended to the analysis of blow fly larval growth based on cephalopharyngeal skeleton. In forensic entomology, cephalopharyngeal skeleton plays a crucial role in species identification but the morphometric information of this part is scarce. In this study, Chrysomya megacephala (Fabricius, 1794) was reared in two study replicates in natural conditions and samplings were conducted at fixed daily intervals. Cephalopharyngeal skeletons were removed from larvae and mounted on glass slides. Images were obtained from the specimens; digitized and geometric morphometric analysis on C. megacephala cephalopharyngeal skeletons was performed with MorphoJ software based on the ordination of five landmarks. The assessments of this analysis were based on centroid size measurements, visualization on the landmarks displacements, classification of the relative landmarks by using canonical variate analysis, and ontogenetic allometry determination. Findings Centroid size was strongly correlated with developmental time (p < 0.05) and significantly different between daily intervals (p < 0.05). Ontogenetic allometric effect based on multivariate regression on Procrustes coordinates and centroid size was significant (p < 0.0001), indicating that shape was influenced by growth (60.3%). Disposition occurred on all landmarks during development and was further discriminated based on age groups. Conclusions Other than discriminating between species, geometric morphometrics was found to be practical to visualize larval growth based on cephalopharyngeal skeletons which can be useful in forensic entomology.

Short Communication: Landmark-based geometric morphometric analysis of wings to distinguish the sex of Aedes mosquito vectors in Thailand

Chaiphongpachara T, Laojun S. 2019. Short Communication: Landmark-based geometric morphometric analysis of wings to distinguish the sex of Aedes mosquito vectors in Thailand. Biodiversitas 20: 419-424. Aedes mosquitoes (Diptera: Culicidae) are medically important insects which are vectors of yellow fever, dengue fever, chikungunya, West Nile, and the Zika virus, emerging problems worldwide. Typically, male (non-vector) and female (vector) Aedes mosquitoes can easily be separated, however, the samples in the field is often incomplete, making it difficult to separate male and female mosquitoes. The goal of this research is to study the effectiveness of the landmark-based geometric morphometric technique to distinguish the sex of male and female Aedes mosquito vectors, including Ae. aegypti, Ae. albopictus, and Ae. scutellaris, in Thailand. Evaluation of wing size by centroid size analysis found that males and females are distinctly different; females are larger than males in three species of Aedes mosquito. The wing centroid size of Ae. aegypti and Ae. albopictus were very similar, however, Ae. scutellaris was smaller than in both other species. The wing shape between sexes was different in all groups of Aedes mosquitoes. The accuracy of the sex’s classification of Aedes vectors was quite high (more than > 80% from the cross-validated reclassification test). The results of this study prove that landmark-based geometric morphometric can distinguish sexes in Aedes vectors which can be used to solve problems in the field when it is necessary to distinguish the sexes of Aedes mosquitoes with damaged samples.