Search

Monomorphism is prevalent among fishes consequently sexually dimorphic traits are unknown. Discrimination between sexes is often achieved through direct examination of the gonads. However, at present, patterns of sexual dimorphism are known through the analysis of body shapes. Thus, this study used landmark based geometric morphometrics to investigate and describe sexual dimorphism in the body shape of Decapterus macrosoma. Fourteen landmarks from images of 60 individuals (25 males and 35 females) were subjected to geometric morphometric analysis. Variability in body shapes between sexes was visualized by generating thine-plate spline expansion plots. Results showed that females exhibited a deeper body depth, broader belly region, bigger head, and wider caudal fin while males exhibited a narrow body depth, smaller head, and wider dorsal and caudal fins. Multivariate analysis of variance and discriminant function analysis showed significant difference in the body shapes between sexes of this fish species (p

Wing geometry helps to identify mosquito species, even cryptic ones. On the other hand, temperature has a well‐known effect on insect metric properties. Can such effects blur the taxonomic signal embedded in the wing? Two strains of Aedes albopictus (laboratory and field strain) were examined under three different rearing temperatures (26, 30 and 33 °C) using landmark‐ and outline‐based morphometric approaches. The wings of each experimental line were compared with Aedes aegypti. Both approaches indicated similar associations between wing size and temperature. For the laboratory strain, the wing size significantly decreased as the temperature increased. For the field strain, the largest wings were observed at the intermediate temperature. The two morphometric approaches describing shape showed different sensibilities to temperature. For both strains and sexes, the landmark‐based approach disclosed significant wing shape changes with temperature changes. The outline‐based approach showed lesser effects, detecting significant changes only in laboratory females and in field males. Despite the size and shape changes induced by temperature, the two strains of Ae. albopictus were always distinguished from Ae. aegypti. The present study confirms the lability of size. However, it also suggests that, despite environmentally‐induced variation, the architecture of the wing still provides a strong taxonomic signal. [ABSTRACT FROM AUTHOR]

A large body of research has shown how avian morphology is shaped by specific behavioral repertoires and life history traits. Yet, the majority of such research has been conducted on birds breeding at north-temperate latitudes. We tested the hypothesis that functional wing traits of Fork-tailed Flycatchers (Tyrannus savana), which migrate within South America, vary predictably between non-migratory and migratory flycatchers. Additionally, due to sex-specific differences in this species (e.g., males perform courtship displays), we explored sex-related variation in wing shape. We applied classic measures of wing shape (e.g., wing loading, length, aspect ratio, pointedness), as well as landmark-based morphometric analysis to describe the wing morphology of Fork-tailed Flycatchers from breeding populations across South America. We found that migratory flycatchers tend to have more pointed wings than non-migratory flycatchers. Additionally, we found that males have wings that are significantly longer, more pointed, with a higher aspect ratio and that are more swept than those of females, regardless of whether they migrate or not. Overall, our results suggest that wing shape of Fork-tailed Flycatchers is the result of a complex set of tradeoffs shaped by selective pressures exerted on both sexes (i.e., the need to forage on the wing, evade predators and migrate efficiently), as well as sex-specific behaviors (e.g., the need for males to execute acrobatic displays). [ABSTRACT FROM AUTHOR]

Using fish scale to identity species and population is a rapid, safe and low cost method. Hence, this study was carried out to investigate the possibility of using geometric and morphometric methods in fish scales for rapid identification of species and populations and compare the efficiency of applying few and/or high number of landmark points. For this purpose, scales of one population of Luciobarbus capito, four populations of Alburnoides eichwaldii and two populations of Rutilus frisii kutum, all belonging to cyprinid family, were examined. On two-dimensional images of the scales 7 and 23 landmark points were digitized in two separate times using TpsDig2, respectively. Landmark data after generalized procrustes analysis were analyzed using Principal Component Analysis (PCA), Canonical Variate Analysis (CVA) and Cluster Analysis. The results of both methods (using 7 and 23 landmark points) showed significant differences of the shape of scales among the three species studied (P0.05). The results also showed that few number of landmarks could display the differences between scale shapes. According to the results of this study, it could be stated that the scale of each species had unique shape patterns which could be utilized as a species identification key.

Using fish scale to identity species and population is a rapid, safe and low cost method. Hence, this study was carried out to investigate the possibility of using geometric and morphometric methods in fish scales for rapid identification of species and populations and compare the efficiency of applying few and/or high number of landmark points. For this purpose, scales of one population of Luciobarbus capito, four populations of Alburnoides eichwaldii and two populations of Rutilus frisii kutum, all belonging to cyprinid family, were examined. On two-dimensional images of the scales 7 and 23 landmark points were digitized in two separate times using TpsDig2, respectively. Landmark data after generalized procrustes analysis were analyzed using Principal Component Analysis (PCA), Canonical Variate Analysis (CVA) and Cluster Analysis. The results of both methods (using 7 and 23 landmark points) showed significant differences of the shape of scales among the three species studied (P<0.001), but no significant differences among their populations (P>0.05). The results also showed that few number of landmarks could display the differences between scale shapes. According to the results of this study, it could be stated that the scale of each species had unique shape patterns which could be utilized as a species identification key. [ABSTRACT FROM AUTHOR]

Relative warp analyses of landmarks describing cranial and mandibular shape are used for investigating patterns of morphological variation among extant bears (Mammalia, Carnivora, Ursidae) indicative of diet and feeding behavior. These patterns are used for deriving inferences about the autecology of two extinct species previously assumed to have had different dietary preferences, the North American giant, short-faced bear Arctodus simus and the Eurasian cave bear Ursus spelaeus. Results reveal a set of shared craniodental traits among the herbivorous bears, including short and vaulted skulls with well-developed zygomatic arches, lateralized orbits and small canines, concave jaws with a highly positioned condyle, large moment arms for the temporalis and masseter muscles, and long cheek teeth. In contrast, those bears that consume animal resources have long skulls with small zygomatic arches, frontalized orbits and well-developed canines, and long jaws with a deep mandibular symphysis, low muscle leverages, a condyle situated at the level of the tooth row and reduced cheek teeth. The craniodental morphology of omnivorous bears is intermediate between those of faunivores and herbivores. This is also the case of the short-faced bear and the cave bear, which suggests that previous reconstructions of the feeding ecology of these extinct species (highly carnivorous for A. simus and herbivorous for U. spelaeus) should be revised. [ABSTRACT FROM AUTHOR]