.— Morphometric studies often consider parts with internal left‐right symmetry, for instance, the vertebrate skull. This type of symmetry is called object symmetry and is distinguished from matching ...symmetry, in which two separate structures exist as mirror images of each other, one on each body side. We explain a method for partitioning the total shape variation of landmark configurations with object symmetry into components of symmetric variation among individuals and asymmetry. This method is based on the Procrustes superimposition of the original and a reflected copy of each landmark configuration and is compatible with the two‐factor ANOVA model customary in studies of fluctuating asymmetry. We show a fully multivariate framework for testing the effects in the two‐factor model with MANOVA statistics, which also applies to shapes with matching symmetry. We apply the new methods in a small case study of pharyngeal jaws of the Neotropical cichlid fish Amphilophus citrinellus. The analysis revealed that the symmetric component of variation in the pharyngeal jaws is dominated by the contrast between two alternative trophic morphs in this species and that there is subtle but statistically significant directional asymmetry. Finally, we provide some general recommendations for morphometric studies of symmetric shapes.
The garfish Belone belone represents the only valid endemic Belone species for the Mediterranean Sea and the eastern Atlantic Ocean. It shows a wide global distribution range, with a high commercial ...value and ecological relevance in the pelagic domain. Despite this, there needs to be more knowledge regarding the otoliths of this species, with the total absence of descriptions regarding asterisci and lapilli from Mediterranean populations and a lack of studies on the reliability of shape analysis on its sagittae. The present paper aims to provide the first main contours description of the three otoliths pairs from a Mediterranean population, providing an accurate investigation of morphology, morphometry, and intra-specific variability of sagittae, lapilli, and asterisci. Results showed (i) the absence of directional bilateral asymmetry and sexual asymmetry for the three otoliths pairs, (ii) a different morphology and morphometry of sagittae, lapilli and asterisci than those described in the literature, and (iii) an enhanced variability between sagittae morphometry and shape between the three investigated size classes. All these data confirmed the reliability of the studied species of shape analysis, showing a geographical and size-related variability of otoliths features probably related to genetics, environmental conditions, and life habits variations.
The lesser mealworm, Alphitobius diaperinus (Panzer, 1797), is a pervasive pest known to infest stored products and poultry facilities worldwide, posing significant challenges for pest management. ...Understanding its adaptability to diverse environments is crucial for devising effective control strategies. This study investigated adult mouthparts and analyzed the mitogenome of A. diaperinus using specimens obtained from a cat litter box. The examination of mouthparts revealed notable intraspecific variations, suggesting potential adaptations to different ecological conditions. Analysis of the mitogenomes unveiled nucleotide variations in protein-coding genes (PCGs), ribosomal RNA genes (rRNAs), and the control region, with all mutations in PCGs being nonsynonymous, primarily occurring at the second codon positions. Evaluation of Ka/Ks ratios indicated purifying selection acting on the PCGs of A. diaperinus. Phylogenetic analyses consistently placed the newly sequenced sample within the same clade as previously sequenced A. diaperinus samples. The presence of A. diaperinus in cat litter highlights its remarkable adaptability to diverse habitats. Furthermore, intraspecific variation in mouthpart morphology and the mitogenome suggests ongoing adaptations to various food sources and environmental niches. These findings underscore the dynamic nature of A. diaperinus adaptations and emphasize the importance of continued research for effective pest management strategies.
•Alphitobius diaperinus mouthparts show morphological variation.•The mitogenomes of the lesser mealworm are comparatively analyzed.•Genetic diversity is evident in A. diaperinus mitogenomes.•All nucleotide mutations in PCGs are nonsynonymous.
The features of aphid biology are determined by the clonal structure of their populations and polymorphism. The alternation of winter (arboreal) and summer (herbaceous) hosts in aphid species is ...accompanied by an annual change in the relative frequencies of clones and morphotypes within clones. Clones and morphotypes are tools to allow aphid populations to remain stable within the same genotypes or form more harmful biotypes. In both cases, it is important to study the relationships between these intrapopulation structures. For the cereal pest Metopolophium dirhodum (Walk.), population formation depends on the diversity of their clonal and morphotypic composition. The parameters of reproduction and settlement for the summer morphotypes (emigrants, apterous and alate exules) of 10 different M. dirhodum clones on wheat were determined. It was shown that the reproductive parameters of individual morphotypes varied significantly among the clones. Compared to apterous or alate exules, the reproduction of emigrants was significantly lower. The reproduction of apterous exules was strongly influenced by the generation time during the summer and annual changes in clonal composition. Alate exules and alatoid nymphs were produced only by apterous exules. The ecological plasticity of aphid populations is determined by their clonal and morphotypic diversity. Clones will be successful when the development of their component morphotypes is optimized. The purpose of this work was to reveal the peculiarities of clonal composition and the developmental characteristics of different summer morphotypes for the rose-grass aphid, Metopolophium dirhodum (Walk.), which is an important host-alternating cereal pest and a useful model species. During the experiments, aphids were kept under ambient conditions on wheat seedlings at natural temperatures and humidity levels. An analysis of the reproduction of summer morphotypes and the resulting composition of offspring found that variation among the clones and morphotypes, as well as generational effects and an influence of sexual reproduction (and interactions between all factors) influenced the population structure of M. dirhodum. The reproduction of emigrants was less among the clones than that of the apterous or alate exules. The number of offspring produced by apterous exules differed throughout the growing season (generational effects) and between years, with different clones exhibiting different responses. There were dispersing aphids only among the offspring of apterous exules. These results can contribute to future advances in the forecasting and monitoring of aphid populations.
Abstract
Ameerega trivittata is a widely distributed dendrobatid species with colour polymorphism for which only the diploid number, nucleolar organizer regions (NORs) and heterochromatic pattern are ...known. Here, we investigated the existence of cytogenetic structure in A. trivittata populations with different morphotypes. Four morphotypes and their geographical distributions were defined. All the individuals have 24 chromosomes and a similar heterochromatic pattern, the same location of telomeric regions and 5S rDNA. The NOR site was coincident with the 18S rDNA in pair 9, but some individuals presented an additional site in one of the homologues of pair 11. The highest variation was found in the microsatellite distribution patterns. Comparing the cytogenetic characters of the individuals, two groups were detected: (1) Tabatinga (morphotype B) and Benjamin Constant (morphotype A), and (2) Presidente Figueiredo and Tefé (morphotype C). The cytogenetic data appear to be correlated to the structure pattern of the morphotypes, and corroborate the dispersal routes proposed in the literature. This is the first study of population cytogenetics for the group. Our results provide a series of cytogenetic characters for A. trivittata and for Dendrobatidae for the first time and highlight the importance of considering cytogenetics in population research.
Abstract The use of species as a concept is an important metric for assessing biological diversity and ecosystem function. However, delimiting species based on morphological characters can be ...difficult, especially in aquatic plants that exhibit high levels of variation and overlap. The Sphagnum cuspidatum complex, which includes plants that dominate peatland hollows, provides an example of challenges in species delimitation. Microscopic characters that have been used to define taxa and the possibility that these characters may simply be phenoplastic responses to variation in water availability make species delimitation in this group especially difficult. In particular, the use of leaf shape and serration, which have been used to separate species in the complex, have resulted in divergent taxonomic treatments. Using a combination of high-resolution population genomic data (RADseq) and a robust morphological assessment of plants representing the focal species, we provide evidence to evaluate putative species in this complex. Our data support the recognition of S. cuspidatum, S. fitzgeraldii, S. mississippiense, and S. trinitense as genetically distinct species that can be separated morphologically. These results indicate that S. viride does not differ genetically from S. cuspidatum. Our results are broadly relevant to other aquatic groups where leaf shape and marginal teeth are used to distinguish species.
Abstract
Phenotypic variation is often used to delineate species and subspecies boundaries. Statistical analysis of phenotypic variation within a species is helpful both for understanding ...biodiversity and for its conservation. At least three named subspecies of barn swallows (Hirundo rustica) have distributions that span China, yet, to date, no systematic study of phenotypic differentiation has been applied to understand the delineation of these subspecies. In this study, we collected 510 samples of barn swallow from 23 populations in China, including two recognized subspecies, H. r. rustica and H. r. gutturalis, and one potential subspecies, H. r. mandschurica. With these samples, we examined and found morphometric and colour differences among different populations. Western Chinese barn swallows (H. r. rustica) have larger body size and could be clearly differentiated from eastern H. r. gutturalis and H. r. mandschurica, while north-eastern populations (named H. r. mandschurica) have darker, redder ventral plumage than H. r. rustica and H. r. gutturalis. However, we inferred that although there were phenotypic differences between H. r. mandschurica and H. r. gutturalis, they were not sufficiently distinct to assign them to separate subspecies based on the 75% rule for defining subspecies.
Characterizing the suture morphological variation is a crucial step to investigate the influence of sutures on infant head biomechanics. This study aimed to establish a comprehensive quantitative ...framework for accurately capturing the cranial suture and fontanelle morphologies in infants. A total of 69 CT scans of 2-4 month-old infant heads were segmented to identify semilandmarks at the borders of cranial sutures and fontanelles. Morphological characteristics, including length, width, sinuosity index (SI), and surface area, were measured. For this, an automatic method was developed to determine the junction points between sutures and fontanelles, and thin-plate-spline (TPS) was utilized for area calculation. Different dimensionality reduction methods were compared, including nonlinear and linear principal component analysis (PCA), as well as deep-learning-based variational autoencoder (VAE). Finally, the significance of various covariates was analyzed, and regression analysis was performed to establish a statistical model relating morphological parameters with global parameters. This study successfully developed a quantitative morphological framework and demonstrate its application in quantifying morphologies of infant sutures and fontanelles, which were shown to significantly relate to global parameters of cranial size, suture SI, and surface area for infants aged 2-4 months. The developed framework proved to be reliable and applicable in extracting infant suture morphology features from CT scans. The demonstrated application highlighted its potential to provide valuable insights into the morphologies of infant cranial sutures and fontanelles, aiding in the diagnosis of suture-related skull fractures. Infant suture, Infant fontanelle, Morphological variation, Morphology analysis framework, Statistical model.
Many actinopterygian fish groups, including fossil and extant polypteriforms and lepisosteiforms, fossil halecomorphs, and some basal teleosts, have stout bony scales covered by layers of ganoin-an ...enamel layer ornamented with minute tubercles. Ganoid scales preserve well as disarticulated remains and notably constitute most of the fossil record for polypteriform in both South America and Africa. Based on two variables (tubercle size and distance between tubercles), some authors reported that the ganoin tubercle ornamentation in these scales is constant within a species and differs between species and allows distinguishing species or at least groups of species. However, despite its promising potential for assessing polypteriform paleodiversity, this tool has remained unused, probably because the variables are not well defined, and intraspecific variation does not seem to have been considered. To address this gap, we aimed to test the intraspecific and intra-individual variation in the ornamentation of ganoid scales in the type species Polypterus bichir. We propose three different parameters to describe the tubercle ornamentation: the distance between contiguous tubercles centers, their density, and their relative spatial organization. With these parameters, we investigate the variation in ganoin ornamentation among four specimens and across different regions of the body. Our results show that the distribution of the tubercles is highly variable within a same species, regardless of the body region, and sometimes even between different sectors of a same scale. Moreover, the variation observed in P. bichir overlaps with the distribution described in the literature for several extant and fossil species. Thus far, the ornamentation of ganoid scales is not a reliable diagnostical feature for polypterids.
The advent of new and powerful mathematical methods allows us to carry out multidimensional analyses of traits. Regarding disparity the number of methods to measure morphological variation within a ...taxonomical group is vast and the choice of a single disparity index can limit the interpretation of the results. The use of two disparity indexes, the sum of ranges and the sum of variances by Hopkins (2022) enriched the work by Suárez & Esteve (2021). The interpretation of the results of any sort is based on the analysed data, in this case our ecomorphological dataset. We point out the importance of an accurate ecomorphological dataset, as taxonomic mistakes or ecological misinterpretations are unavoidable and continuous updating is therefore mandatory. The updated ecomorphological dataset, using appropriate indexes and resampling, provides new and exciting results which show us a new complex scenario in the evolution of trilobites throughout the Palaeozoic.
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