Body Size Research Articles

Revisiting the taxonomy of Korean Ischnochiton species (Polyplacophora, Ischnochitonidae) based on a combined analysis of morphological and molecular data.

Chiton species belonging to the genus Ischnochiton J. E. Gray, 1847 are commonly found in intertidal rocky shores worldwide, with the exception of the northern Atlantic and Arctic oceans. Ischnochiton species are characterised by imbricate girdle scales that are uniform in size, rounded, sculpted with striae or occasionally smooth. However, their species-level taxonomy is complicated due to the high variation in their shell microstructures. Despite more than a hundred species reported worldwide, taxonomic studies of this group remain relatively unexplored in Korean waters, with only a few species recorded to date. In this study, we compared the microstructural characteristics of tegmentum sculpture, girdle scales and radula amongst four Korean Ischnochiton species using high-resolution microscopic images and a scanning electron microscope (SEM). Along with mtDNA cox1 sequence comparison, a comprehensive analysis of their morphology revealed that I.hayamii Owada, 2018 was identified for the first time in Korean waters. This species is morphologically distinguished by its small body size of adults, smooth lateral areas on valves and small perinotum scales sculptured with weak longitudinal ribs. Phylogenetic analysis of the mtDNA cox1 sequence provides distinct resolution at the species level, but interrelationships amongst Ischnochiton species remain unresolved. Results from the morphological and molecular analyses presented in this study offer valuable taxonomic information for accurate species identification amongst closely-related Ischnochiton species.

Field tests reveal acoustic variation of call types in a subterranean rodent, the Northern Mole Vole Ellobius talpinus

Abstract This study investigates acoustic variation of human-audible sonic (below 20 kHz) and human-inaudible ultrasonic (above 20 kHz) calls in a wild subterranean rodent, the Northern Mole Vole (Ellobius talpinus), under 3 call-eliciting tests conducted during captures for 1 day. The Contact-in-Tunnel Test modeled contacts of 2 individuals during digging earth in a burrow tunnel. The Restraint Test modeled restraint of an animal by a surrogate predator (human hand). The Release-to-Burrow Test modeled acoustic communication of many family members returned to their home burrow after their isolation for about 8 h, from morning to evening. We described 8 call types: 3 sonic, 3 ultrasonic, and 2 expanding from sonic to ultrasonic range of frequencies; 6 call types were described for the first time for this species. No relationship was found between acoustic parameters and proxies of body size (body mass and the width of 2 upper incisors). No sex differences were found in body size or the acoustic parameters. Different call types prevailed in different tests: wheeks and upsweeps were made during peaceful interactions; squeaks and squeals were related to animal discomfort during the Restraint Test; rasps were only made in Release-to-Burrow Tests when animals were plugging the burrow entrance; and variative calls did not show any relationship with type of test. Based on presence or absence of certain call types in the tests, we evaluate their potential communicative role in comparison with published data on vocal repertoires of other subterranean rodents.

Investigating the influence of the SIRT6 gene and alternative splicing on canine longevity: an in-depth bioinformatics analysis and experimental confirmation via NGS-based targeted sequencing.

Sirtuin 6 (SIRT6) has many functions, but its most notable contribution lies in the intricate regulation of cell senescence and lifespan. The effect of the SIRT6 gene on body size and longevity in dogs has not been extensively studied, particularly with regard to alternative splicing mechanisms. To address this gap, the present study used a comprehensive approach that integrated bioinformatics analysis, DNA sequence analysis, and next-generation sequencing-based targeted sequencing analyses. Our results show that, according to the reference genomes of different dog breeds, the canine SIRT6 gene exhibits different variants according to the dog breed. Except for the exonic variant g.55,146,051C > T (rs851065050) detected in the Boxer breed, all variants obtained from other genomes were determined to be intronic variants. The g.56,075,604 G > T (rs3343377774) intronic variant previously detected in the Labrador Retriever breed was only detected in the small breed group in our study. As a result of in silico analysis, the g.56,075,604 G > T variant has an exonic splicing enhancer (ESE) site; this variant has created the motif of the binding site for the splicing factor ESE_SRp55. The g.55.146,051C > T variant was associated with a change in the ratio of exonic splicing silencer/ESE binding motifs. This change indicates an increased probability of exon skipping for the mutant allele. Thus, as with the intronic variant g.56,075,604 G > T, the mis-splicing induced by the exonic variant g.55,146,051C > T could potentially be associated with an altered distribution of regulatory splicing factors of the canine SIRT6 gene.

Environmental effects on abundance and size of harvested bivalve populations in intertidal shellfish grounds

Clams, razor clams and cockle are intertidal bivalve species collected on foot in the shellfish grounds of the Rías Altas (NW Spain). Spatio-temporal distribution of these bivalves are typically at the expenses of the environmental conditions of the region; however, the responses to the abiotic conditions are poorly understood. Using data from 6 species (Ruditapes decussatus, Venerupis corrugata, Ruditapes philippinarum, Cerastoderam edule, Donax trunculus and Solen marginatus) sampled in 51 intertidal shellfish grounds during 2007 and 2008, we characterized the influence of the environment (temperature, salinity, nutrient salts, suspended organic matter, or sediment granulometry and composition) on the distribution and size of these species through a comparative statistical analysis. Shellfish grounds were grouped according to their sediment and water characteristics revealing a land-ocean gradient and the influence of the geological imprint that separates bivalve grounds from West to East. Statistical models showed that R. decussatus, V. corrugata and R. philippinarum together with C. edule were more abundant in sites combining a strong marine influence with organic-rich finer sediments. However, each of those species also had different environmental niches mostly related to their particular sediment affinities, the proximity to the river mouth, and their physiological tolerances to temperature and salinity. D. trunculus was only found in outer exposed shellfish grounds, while S. marginatus abundance increased in muddy sediments. River distance was a sound descriptor of individual shell length and length variability with contrasting effects on the different species. Furthermore, slopes of length-weight relationships were steeper in autumn than in spring, and this allometry tended to be more positive in sites located closer to the rivers’ mouth, which had a higher organic matter C/N ratio. Overall, harvested intertidal bivalves had identifiable environmental preferences that influence their spatial distribution in abundance, body size, and allometric growth.

The Current High Bird Colonisation Rate in a Major Mediterranean Island is Consistent With a More Intense Past Defaunation Compared to Nearby Mainland

ABSTRACTAimWe expand here previous own biogeographic work on the determinants of avian colonisation of a major land‐bridge Mediterranean island. So far we have explained mechanistically the high current rate of colonisation of the island which proceeds by overflow of mainland species with growing population trends and with prior experience as winter visitors. However, here we focus on the historical factors that have led to such a high colonisation rate.LocationMajorca Island and a nearby Iberian mainland coastal region with equivalent characteristics (Alicante province).Time PeriodTwenty‐five years (1991–2015).Major Taxa StudiedBirds.MethodsWe compared the pattern of species gain and loss in Majorca and Alicante during the study period.ResultsWe found that while Alicante only gained eight new species and lost one, Majorca lost none and gained 21 species as breeders (odds ratio 2.6). The process of species gains in 5‐year periods since 1991 showed a nonlinear pattern in both regions, with an abrupt decline in Alicante starting in 2006–2010 and final stagnation during 2011–2015, but just a smooth and recent pattern of slowdown in Majorca (2011–2015 on). Taxonomic diversity of colonising species at the family level, as well as habitat of colonisation, were quite similar between regions, but larger body size species were more common in Majorca.Main ConclusionsWe conclude that current differential colonisation rates between both regions are consistent with a more intense past defaunation of the resource‐poor region (Majorca) prior to modern rural flight that happened simultaneously in both regions. While Alicante could be approaching a theoretical carrying capacity in the number of species, Majorca is farther from it. We predict that the island will continue gaining species in the next few decades. Worldwide, further research on comparing wildlife recovery rates between regions with differential intensity of past wildlife defaunation is badly needed to understand biodiversity recovery processes.

Relationship between predation and maternal investment In Curly-Tailed Lizards

The Northern Curly-tailed Lizard (Leiocephalus carinatus armouri) is invasive in Florida, where it has establishedmultiple populations. Like most animals, the species faces various environmental pressures, including predation,which influences reproductive strategies. To test the hypothesis that a correlation exists between predation rates onfemales and offspring-resource allocation, we examined specimens from 11 populations in Florida, assuming that thosewith broken tails had encountered a potential predator. To quantify offspring-resource allocation, we used the numberof ovarian follicles in each female and the ratio of number to average size of the largest follicles. We predicted that thosetraits would differ between lizards with and without broken tails. We did not detect the expected correlation, suggestingthat predation pressure did not affect the number or size of follicles. Consistent with other lizard species, we did findthat larger body size was correlated with a greater number of follicles.

Difference in reproductive traits of two sympatric species of Stigmaphyllon (Malpighiaceae) throughout their distribution range: Are they context-dependent?

Populations of widely distributed plants may experience varying climatic or ecological conditions, leading to uneven evolution of reproductive traits. However, studies on reproductive biology usually focus on just one, or rarely two, sampling areas. In this study, we performed a geographical comparative analysis of the flowering pattern, pollination biology and breeding system of Stigmaphyllon bonariense and S. jatrophifolium (Malpighiaceae) throughout their natural distribution in Argentina, classifying them as ‘northern’ or ‘southern’ according to their geographic location. For this, we selected 4 populations for S. bonariense and 3 for S. jatrophifolium to characterized the flowering peak at both the individual (IFP) and population (PFP) levels, the floral display per inflorescence, the richness of Malpighiaceae species and their pollinators, and the stigmatic and body pollen loads of the pollinators. In addition, we performed manipulative experiments to determine the breeding system. Our results showed that the duration of flowering phenology and the floral display vary between northern and southern populations of both species. These traits include flowering duration and the number of flowers at anthesis per inflorescence (floral display). In addition, the pollination context exhibited latitudinal differences in species richness, phenology, body size of oil-collecting bees, and visitation frequency. Besides, the number of co-flowering Malpighiaceae species varied among populations. However, no considerable differences were observed among populations in terms of stigmatic and body pollen load in pollinators of both species. The breeding system was invariable and consistent in both species with self-incompatibility (SI). These findings suggest that certain reproductive traits of both Stigmaphyllon species are context-dependent and would allow the species maximise reproductive success in each population. Therefore, our results demonstrate that large-scale geographical studies (i.e., several populations with different climatic conditions) and the analysis of various phenological traits are necessary to better understand the reproductive biology of plant species.

Redescription of Proteocephalus fallax La Rue, 1911 (Cestoda) and a list of proteocephalid tapeworms of whitefish (Coregonus spp.).

Tapeworms of the genus Proteocephalus Weinland, 1858 (Cestoda: Proteocephalidae) are common and widespread intestinal parasites of whitefish (Coregonus spp., Salmonidae: Coregoninae). Previous taxonomic studies, based solely on morphology and inconsistently fixed specimens, concluded that all salmoniform fish, including whitefish, are parasitised by a single euryxenous and highly polymorphic species, Proteocephalus longicollis (Zeder, 1800). However, recent molecular phylogenetic analyses have revealed the existence of several species specific to individual genera or even species of salmoniform fish. In this study, Proteocephalus fallax La Rue, 1911 is redescribed based on newly collected and genetically characterised specimens from several Coregonus species in Switzerland, the type locality of the species, and in Norway. This cestode was previously synonymised with P. exiguus La Rue, 1911, a parasite of whitefish in North America, but the two species are not closely related. Proteocephalus fallax differs from P. exiguus in its larger body size, wider proglottids, shorter cirrus sac and broader scolex. In addition, the other Proteocephalus species described in whitefish are briefly discussed, with comments on their validity, host range and distribution.

The interaction of relative age with maturation and body size in female handball talent selection.

The relative age effects (RAEs) and biological maturation are two distinct factors that have been identified to affect talent identification and selection. Previous research has suggested that talent selection should include sport-specific technical tasks instead of body size and/or physical test measurements, assuming that the technical tasks are less influenced by variations in maturation. Our purpose was to examine the prevalence of RAEs and to assess biological maturity, body size, and body composition within a single talent selection program for female handball players. Team coaches' recommendations, handball-specific drills, and in-game performance were the selection criteria. Birth distribution of all U14 female handball players were analysed (N = 3198) grouped in two-year age cohort. Measurements of body size, body composition (InBody 720), and bone age were performed in all players who were selected to participate in the selection program (n = 264) (mean±sd age: 13.1±0.6 years) and in a sample of not-selected players (n = 266) (mean±sd age: 13.2±0.6 years). Players were grouped in quarter-year intervals based on their date of birth. Chi-square was used to examine quartile distributions, differences between quartiles were tested with one-way analysis of variance, whereas differences between the selected and not-selected groups were examined with independent sample t-test (Cohen d effect size). Binary logistic regression was used to determine the effects of the predictors on the selection. In terms of all registered players, there was no difference in birth distribution. RAEs appeared at the first selection stage and were evident at all following stages. Quartiles differed only between the first and the last quartiles in body size and muscle mass. Only bone age differed between consecutive quartile or semi-year groups. Body size, body composition, and maturity had a significant, but of moderate power, effect on the selection. Larger body height increased the likelihood of selection by about 12%, larger muscle mass by 12% to 25%, larger bone age by 350-400%, while larger percent body fat decreased selection chances by 7%. The sport-specific criteria could not eliminate the prevalence of the RAEs. Relative age was connected to bone age, but not convincingly to body size and muscle mass. Although bone age had the largest effect on the selection, this was not associated with larger body size or muscle mass. Early maturation increased selection chances mainly during the coaches' subjective evaluation, but not convincingly when sport-specific tasks were applied. Given that differences were mostly evident between players of more than 1.5-year variation in their chronological age, one-year age cohorts within talent selection or the rotation of the cut-off dates of the bi-annual age grouping could be a promising strategy while also including maturation status and relative age in performance evaluations.

Spatial distribution and fecundity of the cinnamon shrimp, Macrobrachium acanthurus (Wiegmann, 1836) (Crustacea: Decapoda: Palaemonidae) from Jequitinhonha River (BA), Brazil

ABSTRACT Macrobrachium acanthurus is an amphidromous palaemonid shrimp exploited by artisanal fishing in Brazil that presents limited published information on its population biology. Therefore, this study aimed to assess the spatial distribution and fecundity of M. acanthurus in the Jequitinhonha River (BA). Collections occurred at four points in the river downstream of the Itapebi Hydroelectric Powerplant (P1–P4). The abundance and size of the demographic categories analysed (male morphotypes, non-ovigerous females, and ovigerous females) and fecundity were compared among points. We also examined the relationship between female body size and fecundity. A total of 938 individuals were collected during the sampling period. The highest abundances were observed downstream (P3 and P4). The sizes of males and ovigerous females were greater at points farthest upstream. Three male morphotypes were identified, and their proportions varied among points. Fecundity was higher upstream, and there was a positive correlation between female size and number of eggs. All population parameters indicate a longitudinal gradient towards the estuary, with strong evidence of amphidromy. This is the first study with a polymorphic species to consider morphotypes as a population structure component. The results represent an important contribution to a better understanding of the amphidromous life cycle of palaemonid shrimp.

Comparative Genomics of the World's Smallest Mammals Reveals Links to Echolocation, Metabolism, and Body Size Plasticity.

Originating 30 million years ago, shrews (Soricidae) have diversified into around 400 species worldwide. Shrews display a wide array of adaptations, with some species having developed distinctive traits such as echolocation, underwater diving, and venomous saliva. Accordingly, these tiny insectivores are ideal to study the genomic mechanisms of evolution and adaptation. We conducted a comparative genomic analysis of four shrew species and 16 other mammals to identify genomic variations unique to shrews. Using two existing shrew genomes and two de novo assemblies for the maritime (Sorex maritimensis) and smoky (Sorex fumeus) shrews, we identified mutations in conserved regions of the genomes, also known as accelerated regions, gene families that underwent significant expansion, and positively selected genes. Our analyses unveiled shrew-specific genomic variants in genes associated with the nervous, metabolic, and auditory systems, which can be linked to unique traits in shrews. Notably, genes suggested to be under convergent evolution in echolocating mammals exhibited accelerated regions in shrews, and pathways linked to putative body size plasticity were detected. These findings provide insight into the evolutionary mechanisms shaping shrew species, shedding light on their adaptation and divergence over time.

Variability of Morphological Characters of the Genus Alburnoides (Pisces, Leuciscidae) from Watercourses in Southern Russia

The variability of the morphological characters of the genus Alburnoides Jeitteles, 1861 from watercourses in the south of Russia (five rivers of the Crimean Peninsula and two rivers of the Krasnodar Territory) is considered. It has been established that in spirlins within the study areas, body sizes average from 60.1 ± 1.45 mm in individuals from the river Gostagayka (Krasnodar region) up to 88.2 ± 1.87 mm in fish from the river Angara (Crimean Peninsula). Using the Mann–Whitney test, statistically significant differences were registered between the samples in most plastic characters; they were absent in meristic characters. In the studied regions, heterogeneity in the structure of the genus Alburnoides was noted: according to the results of cluster analysis for the totality of all studied characters, the greatest similarity was found in samples from Crimean rivers that are geographically close to each other (rivers Chernaya, Belbek, Kacha and Alma), but group from the river Angara adjoins them at a higher level of divergence. A separate group is formed by samples from the rivers of the Krasnodar Territory. The obtained data are consistent with the literary information on the formation of the ichthyofauna in the rivers of Crimea; the established clear differences between the charaters from the rivers of southern Russia require a more detailed study.

Development and Evaluation of a Wearable Upper Limb Assistive Device with a Remote Center of Motion Mechanism

Workers in factories, construction sites, and farms are often exposed to the risk of physical disability and injury. Particularly, the lower back and shoulders require assistance, as injuries can make it difficult to continue working. While social concern about back injuries is high and preventive measures are taken, lesser attention is paid to shoulders, resulting in inadequate assistance and prevention mechanisms. Therefore, wearable, low-cost, and lightweight upper limb assistive devices that can be used in multiple scenarios are desired by workers. In this study, we proposed a device that uses a remote center of motion (RCM) mechanism, enabling the device to support user’s upper arm from below, and the rotational center of device to correspond with shoulder joint. The theoretical assist torque is designed to be sufficient for arm gravity compensation of Japanese males of standard body size. The calculated theoretical assist torque for each shoulder joint is about 8 Nm and maximum assist force for each arm was about 36.3 N (3.7 kgf). Experimental evaluation using a prototype of this device on three healthy adult males demonstrated a decrease in muscle activity of approximately 38% in the anterior deltoid, 31% in the middle deltoid, and 11% in the posterior deltoid as an average of all results in a dynamic experiment in which the participants performed the indicated movements.

Integrative Taxonomy Revealed High Diversity of Hemiphyllodactylus Bleeker, 1860 (Squamata: Gekkonidae) and the Description of Three New Species from Yunnan Province, China.

The karst landform in Yunnan Province, China, represents one of the most biodiverse regions for Hemiphyllodactylus. Previous research has revealed that the karst forests in this province host a greater diversity of Hemiphyllodactylus than previously acknowledged. However, substantial fundamental data essential for taxonomic and biogeographical studies are lacking. We conducted extensive surveys for Hemiphyllodactylus in the Yunnan Province that led to the discovery of three new species from Menglian Dai, Lahu, and Wa Autonomous County and Jinghong City based on morphological and genetic data. A phylogenetic reconstruction based on the ND2 gene (1038 bp) placed the three new species into clade 3 and clade 4 of Agung et al. The uncorrected genetic pairwise distance of the Menglian specimens were greater than 5.7%, and those of the Jinghong City specimens were greater than 5.2% and 8.5%, respectively. They could be distinguished from their congeners by body size, chin scales, internasal scales, ventral scales, dorsal scales, and the total number of femoral and precloacal pores. Furthermore, we update the distributional knowledge of the known species.

Is sexual size dimorphism in walleye, Sander vitreus, a driver of seasonal movements in Lake Erie?

Walleye (Sander vitreus) are a sexually dimorphic species in which females are larger than males in adulthood. Walleye can also exhibit sex- and population-based differences in migration behavior. In Lake Erie, we used acoustic telemetry to test the prediction that female walleye exhibit larger broad-scale movements than males during the summer and autumn. This prediction was based on the hypothesis that greater foraging in females would be needed to satisfy their higher energy requirements. We quantified movements of males and females from distinct spawning populations from Lake Erie's west and east basins using a lake-wide grid of acoustic receivers in 2017 and 2018. We found no differences between male and female home range sizes, core range sizes, or distances travelled in either population. Fish length-at-tagging was unrelated to the size of a fish's home range or to its distance travelled, contrary to previous predictions about body size as a driver of migration distance in the Lake Erie population. We found that west basin walleye occupied large and indiscrete portions of the lake, but the core range of females extended into the central basin, whereas males were concentrated in the west basin. Walleye originating from the east basin confined their movements primarily to the east basin and showed stronger home range overlap among members of their population than did walleye from the west basin population. Within either population, walleye had more home range overlap with members of the same sex, which likely reflects differences in the migratory tendencies of males and females.

The East Asian species <i>Thermocyclops taihokuensis</i> (Harada 1931) (Crustacea, Copepoda, Cyclopoida) in the Taganrog Bay of Azov Sea

In August–September 2021–2023, the composition and abundance of pelagic Copepoda in the Don River delta and in the eastern part of the Taganrog Bay of Azov Sea were studied. The East Asian copepod, Thermocyclops taihokuensis (Harada 1931) was recorded for the first time from the eastern part of the bay at a water salinity of 3.5–5.8‰. The species must have entered the Taganrog Bay with water from the Don River. The largest population of the invader was registered in the Don River delta in August 2021 ( 7.000 ind./m3); in the bay in September 2023 it reached 4.000 ind./m3. The body size and fertility of the invader were close to those in the Tsimlyansk Reservoir and the Don River. In 2023, the reproduction of T. taihokuensis was noted in the bay with an extremely low (about 1%) proportion of mature individuals in the population. The species seems to have not yet been fully naturalized in the bay, its population still being supported by bioflow from the Don River delta. The potential consequences of the introduction of this alien copepod for the zooplankton of Taganrog Bay are discussed.

A new tiny fossil penguin from the Late Oligocene of New Zealand and the morphofunctional transition of the penguin wing

ABSTRACT The Late Oligocene is a period of high penguin diversity, following major changes in the marine environment at the Eocene/Oligocene boundary and prior to the emergence of crown penguins in the Miocene. Historically, a large morphological gap existed between the most crownward Platydyptes among the Oligocene penguins from New Zealand and the Early Miocene stem penguins such as Palaeospheniscus from South America. Here we describe a new species that contributes to filling this gap. Pakudyptes hakataramea gen. et sp. nov. is the earliest tiny penguin, overlapping in size with the little penguin Eudyptula minor. Its distinctive combination of a well-developed proximal end of the humerus and an archaic elbow joint provides clues to the evolution of penguin wings. Phylogenetic analysis indicates that penguin wings evolved rapidly from the Late Oligocene to the Early Miocene, together with the acquisition of morphofunctional and hydrodynamical characteristics that enable the excellent swimming ability of modern penguins. As an indicator of aquatic adaptation, bone microanatomy shows a comparable structure to that of Eudyptula. The appearance of the smallest body size and the evolution of modern wings may have led to the ecological diversity of modern penguins, which confirms the importance of Zealandia in penguin evolution.

Visual body size estimation in adolescent anorexia nervosa: Behavioural and neurophysiological data suggest intact visual perception and biased emotional attention

Body image disturbance is a key symptom of anorexia nervosa (AN). AN patients report body dissatisfaction and overestimate their own body size in several tasks. This study aimed to clarify whether this overestimation arises from deficits in visual perception. To this end, 36 adolescent restrictive-type AN patients and 42 matched healthy controls performed metric and depictive body size estimation (BSE) tasks. Magneto- and electroencephalography were measured during the size estimation of 66 computer-generated body pictures varying in size from underweight to overweight. AN patients versus controls showed overestimation across self-referential metric and depictive BSE tasks, but similar performance in a depictive BSE task without self-reference and similar early neurophysiological responses. Starting mid-latency (200 ms), AN patients showed relatively more neural activity in response to underweight body pictures and less neural activity in response to higher-weight body pictures in distributed brain regions. A secondary comparison of AN patients with slight vs. distinct overestimation during self-referential BSE uncovered relatively stronger neural responses to body pictures corresponding to the estimated body mass index. These results suggest that body image disturbances in adolescent restrictive-type AN patients depend on self-reference and do not represent a deficit of visual perception, but rather biased emotional attention.

Unveiling the critical role of androgen receptor signaling in avian sexual development

Gonadal hormone activities mediated by androgen and estrogen receptors, along with cell-autonomous mechanisms arising from the absence of sex-chromosome dosage compensation, are key factors in avian sexual development. In this study, we generate androgen receptor (AR) knockout chickens (AR−/−) to explore the role of androgen signaling in avian sexual development. Despite developing sex-typical gonads and gonadal hormone production, AR−/− males and females are infertile. While few somatic sex-specific traits persist (body size, spurs, and tail feathers), crucial sexual attributes such as comb, wattles and sexual behaviors remain underdeveloped in both sexes. Testosterone treatment of young AR−/− males fails to induce crow behavior, comb development, or regression of the bursa of Fabricius, which are testosterone-dependent phenotypes. These findings highlight the significance of androgen receptor mechanisms in fertility and sex-specific traits in chickens, challenging the concept of a default sex in birds and emphasizing the dominance of androgen signaling in avian sexual development.

Normative computed tomography angiography values of the aortic root, aorta, and aortic arch in children.

Our study reports systolic and diastolic ECG-gated CTA Z-scores along with normative curves in relation to BSA for the aortic root, aorta, and aortic arch in children. • Normative data for intracardiac and extracardiac vascular structures in the pediatric population are available for echocardiography, cardiac MRI and non-ECG gated CTA. • Z-scores with standard deviations are commonly used in children, but SDs are not constant across body sizes due to heteroscedasticity. • Allometric exponent was derived for each parameter and the parameter/body surface area (BSA) was established. • This is the first ECG-gated CTA study to provide normative en face systolic, diastolic diameters and cross-sectional areas along with Z-scores and normative curves for the aortic root, aorta and aortic arch in children.