Size and shape of the neurocranium of laying chicken breeds.

The neurocranium in birds provides valuable insights into their morphological diversity, including adaptations related to brain size, facial shaping, and environmental factors. This study analyzes the neurocranial shape characteristics and size of chickens with similar genetic backgrounds. By examining the neurocranial shape variation in chickens of the same age and sex, the study aims to understand the factors contributing to morphological diversity within this specific group. 3D geometric morphometrics was used to analyze 235 neurocrania from four chicken breeds. The analysis revealed significant differences in centroid size among the chicken breeds. The largest neurocranium centroid size was found in Sasso chickens., which were statistically separated from Atak-S. Additionally, centroid size effectively differentiates between Lohmann Brown and Lohmann Sandy chicken breeds. The most significant shape variation concerned the width of the rostral part of the frontal bone. However, according to the PC1 value, the shape variation was observed within rather than between groups. Lohmann Sandy chickens exhibited higher variability in neurocranial shape, suggesting greater shape diversity within this breed than others. As for shape analysis, the breeds showed closer similarity to each other. Lohmann Sandy chickens are characterized by positive PC1 value, with the rostral end of the frontal region inclined more ventrally, and a more extensive basioccipital region. Sasso chickens have a more dome-shaped middle part of the frontal region than other breeds. The study also identified the most significant shape variation among the study samples, observed at the rostral part of the frontal bone. These findings contribute to understanding the genetic and environmental influences shaping neurocranial morphology in chickens. Similar studies in different bird species and subspecies offer valuable insights into avian biology and adaptation.

Shape variations of pelvis in different classes of dogs using geometric morphometry.

The ossa coxae are the bones that connect the hindlimbs to the axial skeleton. The right and left os coxae join at the median plane to form the pelvis. In this study, variations in pelvis shape and the asymmetric structure of the pelvis were investigated across different classes of dogs. To achieve this, computed tomography images of the pelvis were obtained from 35 dogs, and 3D modelling of the pelvis was created. Subsequently, 45 landmarks were identified on these models. As a result of the Principal Component Analysis, the shape variation was observed in the pelvic canal and crista iliaca. Directional asymmetry between Principal Component 1 and Principal Component 2 accounted for 33.84% of the total variation, while fluctuating asymmetry contributed 23.66%. Canonical variate analysis revealed that canonical variate (CV) 1 explained 56.56% of the total variation between groups, with CV 2 explained 28.98%. Male dogs exhibited greater pelvic variation than females. Procrustes ANOVA indicated that the greatest proportion of shape variation corresponds to the effect of differences among individuals. While directional asymmetry was statistically significant, fluctuating asymmetry was not. Male dogs displayed more pronounced pelvic shape asymmetry, typically towards the right. Gundogs had a narrower pelvic canal and a wide crista iliaca, whereas terriers had a wider pelvic canal and smaller crista iliaca in shape. Geometric morphometry enables statistical analysis and the derivation of average shapes from samples, making it a vital tool in veterinary anatomy. This study provides insights into pelvic geometric morphometry across different classes of dogs.

Geometric morphometric analysis of beak shape of Columbimorphae (Columbas, Van, Mardin and Dönek).

Selective breeding over centuries has led to the emergence of numerous pigeon breeds from the single species Columba livia, showcasing unparalleled phenotypic diversity. In Eastern Turkey, Van pigeons originate, while Tumbler pigeon varieties thrive countrywide, reflecting local traditions. The avian beak, vital for survival, offers insights into domestication and traits influenced by natural selection. Geometric morphometrics, a shape analysis method, allows for a comprehensive examination of beak shapes among domestic pigeons, providing a nuanced understanding of their complexity. Understanding beak diversity in pigeons, especially those found in Turkey, enhances our knowledge of avian evolution and adaptation processes. The study utilized 48 skulls from 4 pigeon breeds, including wild rock pigeons and domestic pigeons of Tumbler, Mardin and Van breeds, all free from pathological lesions and adults. Geometric morphometric analyses of beak shape were conducted using dorsal and lateral photographs, with landmarks placed using tpsDig software. MorphoJ software facilitated procrustes analysis and principal component analysis (PCA) to assess morphological variability and differentiate pigeon breeds based on shape patterns, with significance set at p < 0.05. PCA revealed significant shape variations among pigeon breeds, with 47 principal components identified for lateral beak views and 36 principal components for dorsal views. Canonical variates analysis further distinguished morphological patterns among breeds, indicating distinct shape variations in both dorsal and lateral views, elucidating the unique characteristics of each breed's beak morphology. Our results demonstrate statistically significant differences in pigeon beak shape, particularly in the lateral view, confirming the importance of these variations (p < 0.05) and suggesting that such differences occur less than 5% of the time under the null hypothesis.

Comparative Cranial Geometric Morphometrics among Wistar Albino, Sprague Dawley, and WAG/Rij Rat Strains.

This research utilizes geometric morphometrics to investigate shape variation in the skull, mandible, and teeth among three rat strains: Wistar Albino (WA), Sprague Dawley (SD), and WAG/Rij (WR). Through the analysis of 48 rats using 2D geometric morphometric techniques, significant differences in their skull morphology were identified. This study indicates a shift from a rectangular to an oval cranial shape across strains, with notable size and morphological variances. Particularly, the WR strain's skull shape significantly differs from the SD and WA strains, suggesting distinct ecological or genetic pathways. Compared to the skull, mandible shape differences are less pronounced, but still significant. The WR strain exhibits a distinct mandible shape, potentially reflecting ecological adaptations like dietary habits. The teeth shape of WR rats is the most distinct. SD rats consistently exhibited larger sizes in both skull and mandible measurements, while WR rats were notably smaller. Interestingly, sexual dimorphism was not statistically significant in skull and teeth sizes, aligning with findings from previous studies. However, the mandible showed clear size differences between sexes, underscoring its potential for adaptive or behavioral studies. In summary, this study provides a comprehensive analysis of morphological variations in rat strains, highlighting the intricate interplay of size, shape, and ecological factors. These findings lay a foundation for deeper explorations into the adaptive, ecological, or genetic narratives influencing rat morphology.

Skull asymmetry in various sheep breeds: Directional asymmetry and fluctuating asymmetry.

Sheep (Ovis aries) play an important role in the economy of Turkey and the Balkan Peninsula due to their use in farming. As a domesticated species, sheep's morphometric and morphological diversity is likely determined by selective breeding practices rather than geographic distribution. This study aimed to analyse four different sheep breed skulls and reveal skull asymmetry using geometric morphometric methods. For this purpose, 2D images of 52 sheep skulls from different breeds were analysed from the dorsal view of the skull, using 28 landmarks. In the comparison of sheep skulls from the dorsal view, the first principal components for directional asymmetry (DA) and fluctuating asymmetry (FA) were 32.98% and 39.62% of the total variation, respectively. Sharri and Ivesi (Awassi) sheep breeds had the broadest distribution of skull shapes among the breeds, while Lara e Polisit was the most conservative breed. DA was used as a measure of biomechanical constraints, and FA was used as an indicator of environmental stress. Consistent with DA, both differences in centroid size and shape between breeds were statistically significant. No differences between males and females related to asymmetry were revealed. Ivesi sheep revealed the highest fluctuating asymmetry. Geometric morphometric methods proved to be a useful tool for distinguishing differences in the shape of the skull of different sheep breeds and also can be useful for taxonomic purposes.

Shape and Size Variations of Distal Phalanges in Cattle.

Studies on the structure of the distal phalanx help explain the development of laminitis. Additionally, examining the structure of the distal phalanx from a taxonomic perspective also contributes to veterinary anatomy. In this study, we examined shape variation in the medial and lateral distal phalanx of both fore- and hindlimbs using the geometric morphometry method. We investigated whether the shape of the distal phalanx differed between phalanx positions and how much of the shape variation in this bone depends on size. For this purpose, distal phalanges from 20 Holstein cattle were used, and the bones were digitized in 3D. A draft containing 176 semi-landmarks was prepared for shape analysis, and this draft was applied to all samples using automated landmarking through point cloud alignment and correspondence analysis. A principal component analysis was performed to obtain general patterns of morphological variation. The centroid size (CS) was employed as an approximation of size. Although distal phalanx groups generally showed close variations, PC1 statistically separated the hindlimb lateral distal phalanx (HL) and the forelimb medial distal phalanx (FM) from each other in shape. While PC2 separated HL from other distal phalanx groups, PC3 separated fore- and hindlimb groups. The shape (Procrustes distance) of the hindlimb medial distal phalanx (HM) is markedly less variable than the other three phalanges. The smallest distal phalanx in size was HL. For both forelimb and hindlimb, the medial distal phalanges were larger than the lateral ones. Size (CS) was found to have an effect on PC1 and PC3. In this study, a reference model of the same breeds for distal phalanx was created. These results can provide useful information, especially in terms of veterinary anatomy, zooarchaeology, and paleontology.

Pelvis shape analysis with geometric morphometry in crossbreed cats.

In this study, the geometric morphometry of the pelvis of 32 (16 male, 16 female) crossbreed cats was investigated. Pelvis images of cats were obtained by computerized tomography method. Then, these images were modelled and geometric morphometry was applied. Shape variations of the pelvis of all individuals were obtained by principal component analysis. The first principal component (PC1) value explained 18.44% of the total variation. Second principal component (PC2) and third principal component (PC3) values explained 16.84% and 13.60% of the total variation, respectively. The difference in the shape of the pelvis of female and male cats was more pronounced in PC2 and PC3, which differed in the linea terminalis. The centroid size difference in terms of sex in the Procrustes ANOVA result is statistically insignificant (p > 0.05). However, the shape difference was statistically significant (p < 0.001). As a result of discriminant analysis, the pelvis of female and male cats was completely separated from each other. The crista iliaca of males was more lateral than females. Linea terminalis was wider in shape in females. The edge of the acetabulum was higher in shape in males. Regression analysis was performed to see whether the age and weight of the cats had an effect on the centroid size of the cats. Age and weight were not found to be effective on centroid size. The shape variations of the anatomical formations obtained by geometric morphometry method can be revealed, and it can be examined whether there is a shape difference between the groups.