Allometric body shape changes and morphological differentiation of Shemaya, Alburnus chalcoides (Guldenstadf, 1772), populations in the southern part of Caspian Sea using Elliptic Fourier analysis

BackgroundBody shape can be both a consequence and cause of a species’ evolution and ecology. There are many examples of phenotypes associated with specific ecological niches, likely as a result of specific selective regimes. A classic example of this is the phenotypic change associated with colonization of caves, including body and limb elongation. However, studies explicitly testing for differences in body shape between cave-dwelling and non-cave-dwelling lineages have been limited and so the role of the cave environment in determining morphological characteristics is still not completely understood. Here we examine variation in body shape among 405 individuals representing 20 species in the salamander genus Eurycea (Plethodontidae) and select outgroups exhibiting great diversity in morphology, ecological niche, and life history.ResultsAfter analyzing morphometric data in a phylogenetic context using phylogenetic MANOVA and examination of the phylomorphospace, we found significant differences in body shape among cave-dwelling and non-cave-dwelling species and between aquatic and terrestrial species. Notably, limb elongation and reduced body and tail size characterized cave-dwelling species. Terrestrial species also exhibited elongation of the limbs and digits. We also observed differences in shape variance among paedomorphic and biphasic species. Our results suggest that the functional limitations imposed by habitat and life history played a key role in the evolution of body shape in this group in the context of their phylogenetic history.

Changes in body shape, fluctuating asymmetry (FA) and crypsis were compared among Atlantic salmon Salmo salar fry kept as controls in captivity and those released and subsequently recaptured in the wild according to a before-after-control-impact (BACI) design. Hatchery fish that survived in the wild became more cryptic and displayed a much lower incidence of fin erosion and of asymmetric individuals than control fish kept in captivity. Significant differences in body shape were also apparent, and survivors had longer heads, thicker caudal peduncles and a more streamlined body shape than hatchery controls as early as 20 days following stocking, most likely as a result of phenotypic plasticity and non-random, selective mortality of maladapted phenotypes. Hatchery-reared fish typically perform poorly in the wild and the results of this study indicate that this may be due to phenotypic mismatch, i.e. because hatcheries generate fish that are phenotypically mismatched to the natural environment.

Comparisons within and among populations offer important insights into variation in life‐history traits and possible adaptive patterns to environmental conditions. We present the results of observed differences in body size, body shape and patterns of reproduction in four separate populations of the European pond turtle Emys orbicularis in central and southern Italy – coastal (n=3) and mountainous (n=1) sites and pond (n=2) and canal (n=2) habitats – to determine whether phenotypic plasticity affects reproductive output. Although we did not find any significant latitudinal variation in body size, we observed significant differences in body shape between canal (rounded body shape) and pond (elongated body shape) systems and smaller size with rounded shape in the mountainous population. Reproductive output is similar among populations (median=5 eggs per clutch), whereas reproductive investment (relative clutch mass to maternal body mass) is higher in the mountain population (one clutch per year) than in coastal populations (two clutches per year), suggesting differential trade‐offs between geographic locality, elevation and habitat type. Turtle shell shape and geographic location together affect reproductive output in E. orbicularis in Italy.

Multiple highly divergent lineages have been identified within Ligia occidentalis sensu lato, a rocky supralittoral isopod distributed along a ~3000km latitudinal gradient that encompasses several proposed marine biogeographic provinces and ecoregions in the eastern Pacific. Highly divergent lineages have nonoverlapping geographic distributions, with distributional limits that generally correspond with sharp environmental changes. Crossbreeding experiments suggest postmating reproductive barriers exist among some of them, and surveys of mitochondrial and nuclear gene markers do not show evidence of hybridization. Populations are highly isolated, some of which appear to be very small; thus, the effects of drift are expected to reduce the efficiency of selection. Large genetic divergences among lineages, marked environmental differences in their ranges, reproductive isolation, and/or high isolation of populations may have resulted in morphological differences in L. occidentalis, not detected yet by traditional taxonomy. We used landmark-based geometric morphometric analyses to test for differences in body shape among highly divergent lineages of L. occidentalis, and among populations within these lineages. We analyzed a total of 492 individuals from 53 coastal localities from the southern California Bight to Central Mexico, including the Gulf of California. We conducted discriminant function analyses (DFAs) on body shape morphometrics to assess morphological variation among genetically differentiated lineages and their populations. We also tested for associations between phylogeny and morphological variation, and whether genetic divergence is correlated to multivariate morphological divergence. We detected significant differences in body shape among highly divergent lineages, and among populations within these lineages. Nonetheless, neither lineages nor populations can be discriminated on the basis of body shape, because correct classification rates of cross-validated DFAs were low. Genetic distance and phylogeny had weak to no effect on body shape variation. The supralittoral environment appears to exert strong stabilizing selection and/or strong functional constraints on body shape in L. occidentalis, thereby leading to morphological stasis in this isopod.

The taxonomic uncertainty surrounding cryptic species complexes has traditionally been resolved using lengthy experimental approaches, while, since the advent of PCR based techniques the number of cryptic species described in a variety of taxa is increasing steadily. Here we formally describe a new rotifer species of the Brachionus plicatilis complex: Brachionus manjavacas n.sp., disentangling what was known as a morphological stasis. Detailed morphological analyses demonstrated significant differences in body shape and size between B. manjavacas and B. plicatilis s.s., analysed by geometric morphometrics; unfortunately these statistical differences are not taxonomically reliable because of wide overlaps. Size and asymmetry of masticatory apparatus, named trophi, observed by SEM, gave similar results, with taxonomic ambiguity. Only the shape of small pieces of the trophi, named satellites, were consistently different between the species. On a strictly classical taxonomical basis it is absolutely useful to name new species on morphological bases, as we did, and to assess their status as distinct entities. Nevertheless, the two species are broadly similar; therefore, we do not suggest using the small differences in shape of satellites of trophi to identify the species for further ecological studies, but to continue discriminating them on genetic marker bases.

The anglerfishes and allies (Lophioidei) are a diverse group of fishes with over 400 carnivorous species that are renowned for their remarkable hunting behavior employing a modified first dorsal-fin spine to lure prey and adaptations such as "pseudo-walking," bioluminescence, and parasitic sexual dimorphism. Gaining a comprehensive understanding of their evolutionary history has been challenging, as previous studies using DNA sequence data or morphological traits have provided either inconsistent or contradictory results. We present a new comprehensive phylogenetic framework for the evolution of the Lophioidei, combining ultraconserved elements (UCEs), mitochondrial DNA sequence data, and morphological characters. Our findings reveal a monophyletic Lophioidei, positioned as the sister group to the Tetraodontoidei within a broader acanthuriform radiation. Goosefishes (Lophioideo) emerge as the stem anglerfish lineage, forming a sister clade with frogfishes (Antennarioideo) + batfishes (Ogcocephaloideo) and coffinfishes (Chaunacoideo) + deep-sea anglerfishes (Ceratioideo). We expanded the Antennariidae to include all previous frogfish (antennarioid) families as subfamilies while proposing a new subfamily, Fowlerichthyinae, to produce a stable monophyletic taxonomy for the Antennarioideo. Further, we evaluated previously and newly proposed morphological characters to diagnose the Lophioidei and Lophioideo. Our investigations demonstrated that several traditional synapomorphies are no longer diagnostic for the Lophioidei. Based on our phylogeny, a geometric morphometric analysis revealed significant differences in body shape among lophioid infraorders, especially in frogfishes and deep-sea anglerfishes, indicating the importance of habitat transitions on body-shape evolution. This study, integrating genome-scale nuclear, mitochondrial, and morphological data, provides a total-evidence perspective on the evolutionary history of lophioids and sheds light on their specializations and body-shape changes as they transitioned across and within environments.

In this study we investigated the developmental basis of adult phenotypes in a non-model organism, a polymorphic damselfly (Ischnura elegans) with three female colour morphs. This polymorphic species presents an ideal opportunity to study intraspecific variation in growth trajectories, morphological variation in size and shape during the course of ontogeny, and to relate these juvenile differences to the phenotypic differences of the discrete adult phenotypes; the two sexes and the three female morphs. We raised larvae of different families in individual enclosures in the laboratory, and traced morphological changes during the course of ontogeny. We used principal components analysis to examine the effects of Sex, Maternal morph, and Own morph on body size and body shape. We also investigated the larval fitness consequences of variation in size and shape by relating these factors to emergence success. Females grew faster than males and were larger as adults, and there was sexual dimorphism in body shape in both larval and adult stages. There were also significant effects of both maternal morph and own morph on growth rate and body shape in the larval stage. There were significant differences in body shape, but not body size, between the adult female morphs, indicating phenotypic integration between colour, melanin patterning, and body shape. Individuals that emerged successfully grew faster and had different body shape in the larval stage, indicating internal (non-ecological) selection on larval morphology. Overall, morphological differences between individuals at the larval stage carried over to the adult stage. Thus, selection in the larval stage can potentially result in correlated responses in adult phenotypes and vice versa.

Flow characteristics are a prominent factor determining body shapes in aquatic organisms, and correlations between body shape and ambient flow regimes have been established for many fish species. In this study, we investigated the potential for a brief period of extreme flow to exert selection on the body shape of juvenile climbing Hawaiian gobiid fishes. Because of an amphidromous life history, juvenile gobies that complete an oceanic larval phase return to freshwater habitats, where they become adults. Returning juveniles often must scale waterfalls (typically with the use of a ventral sucker) in order to reach the habitats they will use as adults, thereby exposing these animals to brief periods of extreme velocities of flow. Hydrodynamic theory predicts that bodies with larger suckers and with lower heights that reduce drag would have improved climbing success and, thus, be well suited to meet the demands of the flows in waterfalls. To test the potential for the flow environment of waterfalls to impose selection that could contribute to differences in body shape between islands, we subjected juvenile Sicyopterus stimpsoni to climbing trials up artificial waterfalls (∼100 body lengths) and measured differences in body shape between successful and unsuccessful climbers. Waterfalls appear to represent a significant selective barrier to these fishes, as nearly 30% failed our climbing test. However, the effects of selection on morphology were not straightforward, as significant differences in shape between successful and unsuccessful climbers did not always match hydrodynamic predictions. In both selection experiments and in adult fish collected from habitats with different prevailing conditions of flow (the islands of Hawai'i versus Kaua'i), lower head heights were associated with exposure to high-flow regimes, as predicted by hydrodynamic theory. Thus, a premium appears to be placed on the reduction of drag via head morphology throughout the ontogeny of this species. The congruence of phenotypic selection patterns observed in our experiments, with morphological character divergence documented among adult fish from Hawai'i and Kaua'i, suggests that differences in morphology between subpopulations of adult climbing gobies may result, at least in part, from the selective pressures of high-velocity flows encountered by migrating juveniles.

Dimorphisms between the sexes are common in vertebrates and may reflect the divergent selective pressures operating on each sex. For example, in species where males do not show territory defense or pronounced male–male combat, females are typically larger than males as fecundity selection will favor large female body size. This is often the case in frogs where male–male competition is limited to calling behavior. Yet, whether differences in reproductive strategies between the two sexes are reflected in shape dimorphisms, and how those differences in shape may affect relevant whole‐organism performance traits, remains poorly studied. Here we use Xenopus tropicalis frogs to test for intersexual differences in body size, body shape and locomotor performance traits. Our results show that females are larger than males, but that males have relatively longer limbs and heads than females. In absolute terms, males and females perform equally well at different locomotor tasks (burst performance and maximal exertion capacity). Yet, for a given body size, males have a higher exertion capacity than females. Increased exertion capacity in males is likely the consequence of their relatively longer limbs and may reflect selection on locomotor capacity in males to compensate for their smaller absolute body size.

This study quantified differences in body shape of people differing in body mass index (BMI), using three-dimensional (3D) scan-extracted segmental body volumes. Eight segmental volumes were measured on 340 young adults (169 males and 171 females) aged 18-30 years, using the Vitus Smart 3D whole body scanner. Body volumes were also expressed as a ratio of the sex-specific mean volume (segmental or whole body) and compared to BMI using simple linear regression, multiple-segment-linear regression and Lowess curves. While all segmental volumes increased significantly as BMI increased, the BMI-related patterns of increase varied among different body segments. For example, pelvis and abdomen volumes increased at a significantly greater rate than whole body volume, with the rates of increase greatest in the overweight and obese. Body shape changes due to variations in body volume could have important implications in a range of fields that currently use 1D anthropometric measurements that do not capture body shape differences in the same detail.

Geometric morphometrics is widely used to quantify morphological variation between biological specimens, but the fundamental influence of operator bias on data reproducibility is rarely considered, particularly in studies using photographs of live animals taken under field conditions. We examined this using four independent operators that applied an identical landmarking scheme to replicate photographs of 291 live Atlantic salmon (Salmo salar L.) from two rivers. Using repeated measures tests, we found significant inter-operator differences in mean body shape, suggesting that the operators introduced a systematic error despite following the same landmarking scheme. No significant differences were detected when the landmarking process was repeated by the same operator on a random subset of photographs. Importantly, in spite of significant operator bias, small but statistically significant morphological differences between fish from the two rivers were found consistently by all operators. Pairwise tests of angles of vectors of shape change showed that these between-river differences in body shape were analogous across operator datasets, suggesting a general reproducibility of findings obtained by geometric morphometric studies. In contrast, merging landmark data when fish from each river are digitised by different operators had a significant impact on downstream analyses, highlighting an intrinsic risk of bias. Overall, we show that, even when significant inter-operator error is introduced during digitisation, following an identical landmarking scheme can identify morphological differences between populations. This study indicates that operators digitising at least a sub-set of all data groups of interest may be an effective way of mitigating inter-operator error and potentially enabling data sharing.

Pre- and post-weaning functional demands on body size and shape of mammals are often in conflict, especially in species where weaning involves a change of habitat. Compared with long lactations, brief lactations are expected to be associated with fast rates of development and attainment of adult traits. We describe allometry and growth for several morphological traits in two closely related fur seal species with large differences in lactation duration at a sympatric site. Longitudinal data were collected from Antarctic ( Arctocephalus gazella (Peters, 1875); 120 d lactation) and subantarctic ( Arctocephalus tropicalis (Gray, 1872); 300 d lactation) fur seals. Body mass was similar in neonates of both species, but A. gazella neonates were longer, less voluminous, and had larger foreflippers. The species were similar in rate of preweaning growth in body mass, but growth rates of linear variables were faster for A. gazella pups. Consequently, neonatal differences in body shape increased over lactation, and A. gazella pups approached adult body shape faster than did A. tropicalis pups. Our results indicate that preweaning growth is associated with significant changes in body shape, involving the acquisition of a longer, more slender body with larger foreflippers in A. gazella. These differences suggest that A. gazella pups are physically more mature at approximately 100 d of age (close to weaning age) than A. tropicalis pups of the same age.

Changes in body shape are linked to swimming performance and become relevant for selective breeding programmes in cultured finfish. We studied how the selection for fast growth could affect phenotypes by investigating the relationship between swimming performance and body shape. We also investigated how swimming might affect plasma metabolite concentrations. Critical swimming speed (UCrit), body traits (e.g., BW, body weight; BL, body length; K, condition factor), and plasma lactate and glucose concentrations were evaluated in two cohorts of Australasian snapper (Chrysophrys auratus): one derived from wild broodstock (F1), and the other selected for fast growth (F4). UCrit tests (n = 8) were applied in groups of 10 snapper of similar BW (71.7 g) and BL (14.6 cm). The absolute or relative UCrit values of both cohorts were similar (0.702 m⋅s-1 and 4.795 BL⋅s-1, respectively), despite the F4 cohort displaying a higher K. A positive correlation between K and absolute UCrit (Pearson's r = 0.414) was detected in the F4 cohort, but not in the F1 cohort, which may be linked to differences in body shape. A negative correlation between relative UCrit and body size (Pearson's r between -0.682 and -0.501), but no correlation between absolute UCrit and body size, was displayed in both cohorts. Plasma lactate and glucose concentrations were higher in the F4 cohort at UCrit. Whether a longer selective breeding programme could result in more changes in body shape, potentially affecting swimming performance, should be explored, along with the potential outcomes of the differences in metabolic traits detected.

Results A strong negative correlation between perceived concern on body shape and perceived self esteem was identified, Spearman's rs(190) = 0.63, p < 0.001, with high levels of perceived concern on body shape associated with lower levels of perceived self esteem. A Mann Whitney statistical test was conducted to investigate if there is a significant difference between body shape and self esteem scores of males and females. There was no statistically significant difference in body shape scores of males and females, but there was a statistically significant difference in self esteem scores between men and women (p < 0.001), with lower scores on self esteem occurring at women. To investigate if there is a significant difference in body shape and self esteem scores within the five Body Mass Index categories that we had divided our sample in, according to WHO's criteria (1995) for the definition of obesity, Kruskal-Wallis tests were conducted. Results indicate a significant difference in body shape (p < 0.001) and self esteem scores (p < 0.001) across the different BMI groups. Subsequent Mann Whitney tests have demonstrated a significant statistical difference in Body Shape scores between all of the BMI categories except from categories 3 and 4, 3 and 5, and 4 and 5. Results were reproduced for self esteem scores across the same categories.

Among the environmental factors, water temperature has a significant effect on many aspects of fish life. This study was carried out to examine effects of water temperature on body shape of Nile tilapia, Oreochromis niloticus during the early stages of life using truss network system. A total of 150 newly-born fry were reared in three temperature treatments (22, 28 and 34°C) for 40 days. At the end of experiment, the left side of the specimens was photographed. To achieve the body shape data, 13 landmark-points were digitized using tpsDig2 software. The extracted data were justified with generalized procrustes analysis, then the differences of body shape among groups were investigated using the principal component analysis (PCA), canonical variate analysis (CVA) and cluster analysis (CA). There were significant differences in body shape of the treatments. The results of CVA and CA indicated that one of the important factors in the aquatic habitats is water temperature that influences the body shape of the Nile tilapia during the first stages (larval and juvenile stages) of growth.