Search Results (78)

Background/Objectives: The incorporation of the human growth and development literature, an ontogenetic framework, a large virtual sample of individuals across the entire growth period, and a contemporary sample of adult individuals provides a unique opportunity to explore the cranial complex across the entire life cycle. This study (1) assesses cranial variation in postnatal ontogeny to determine the life history stage during which subadult crania can reach comparable levels of phenotypic expression to adult crania and (2) exposes when biological sex can be estimated using craniometric data from immature individuals with accuracy levels comparable to adults. Methods: Contemporary individuals between birth and 102 years of age from one virtual (Subadult Virtual Anthropology Database; SVAD) and one skeletal (Forensic Data Bank; FDB) collection were used in the analyses (n = 2152). Results: Discriminant analysis reveals a clear ontogenetic trajectory across the life history stages, with adolescents, SVAD adults, and FDB adults exhibiting similar cranial dimensions. The analysis also revealed a shift from the growth energetic period into the reproductive energetic period during adolescence. This transition is reflected in the divergence of male and female craniometrics in adolescence, which is also when sex estimation accuracy is comparable to SVAD and FDB adults. Conclusions: The current study argues that skeletal and/or dental maturity is not necessary to estimate sex using the cranium and urges the field to reconsider methodological divisions between subadults and adults. Full article

The blue shark (Prionace glauca) is a pelagic species widely distributed in the northwestern Pacific Ocean. The trophic roles of blue sharks across different developmental stages and between sexes remain poorly understood. Fifty-four sharks were sampled (October 2022–March 2024) for precaudal length (PCL) and stable isotope levels (δ¹³C, δ¹⁵N) in the muscle tissue (n = 52). Mean PCL varied based on the month of sampling (p = 0.034), with the smallest individuals occurring in July (143.0 ± 4.3 cm) and the largest in October (178.0 ± 2.6 cm). Stable isotope analysis (δ¹³C and δ¹⁵N) indicated consistent offshore habitat use (δ¹³C: from −20.70 to −18.82‰) and significant nitrogen isotopic differences among life history (δ¹⁵N: from 10.23 to 15.72‰; Kruskal–Wallis test, p = 0.037). The elevated δ¹⁵N values observed in the subadult group (relative to juvenile individuals) are likely due to trophic enrichment associated with morphological development. Females exhibited markedly larger isotopic niches (SEAc = 2.42‰²) than did males (0.57‰²), and niche overlap was greater within each sex (40–52%) than between sexes (<21%). These results revealed sex-specific ecological roles and trophic strategies throughout the life history of P. glauca. Understanding these foraging differences can help with catch reduction and habitat-protection measures in the transboundary pelagic fisheries of the northwestern Pacific. Full article

Although cranial growth has been extensively explored, forensic and biological anthropology lack a formal incorporation of how cranial growth processes impact the adult phenotype and downstream biological profile estimations. Objectives: This research uses an ontogenetic framework to identify when interlandmark distances (ILDs) stabilize during growth to reach adult levels of variation and to evaluate patterns of cranial sexual size dimorphism. Methods: Multivariate adaptive regression splines (MARS) were conducted on standardized cranial ILDs for 595 individuals from the Subadult Virtual Anthropology Database (SVAD) and the Forensic Data Bank (FDB) aged between birth and 25 years. Cross-Validated R-squared (CVRSq) values evaluated ILD variation explained by age while knot placements identified meaningful changes in ILD growth trajectories. Results: Results reveal the ages at which males and females reach craniometric maturity across splanchnocranium, neurocranium, basicranium and cross-regional ILDs. Changes in growth patterns observed here largely align with growth milestones of integrated soft tissue and skeletal structures as well as developmental milestones like puberty. Conclusions: Our findings highlight the variability in growth by sex and cranial region and move forensic anthropologists towards recognizing cranial growth as a mosaic, continuous process with overlap between subadults and adults rather than consistently approaching subadult and adult research separately. Full article

The distinctive leaf and twig heteromorphism in Euphrates poplar (Populus euphratica Oliv.) reflects its adaptive strategies to cope with arid environments across ontogenetic stages. In the key distribution area of P. euphratica forests in China, we sampled P. euphratica twigs (which grow in the current year) at different age classes (1-, 3-, 5-, 8-, and 11-year-old trees), then analyzed their morphological traits, biomass allocation, as well as allometric relationships. Results revealed significant ontogenetic shifts: seedlings prioritized vertical growth by lengthening stems (32.06 ± 10.28 cm in 1-year-olds) and increasing stem biomass allocation (0.36 ± 0.14 g), while subadult trees developed shorter stems (6.80 ± 2.42 cm in 11-year-olds) with increasesd petiole length (2.997 ± 0.63 cm) and lamina biomass (1.035 ± 0.406 g). Variance partitioning showed that 93%–99% of the trait variation originated from age and individual differences. Standardized major axis analysis demonstrated a consistent “diminishing returns” allometry in biomass allocation (lamina–stem slope = 0.737, lamina–petiole slope = 0.827), with age-modulated intercepts reflecting developmental adjustments. These patterns revealed an evolutionary trade-off strategy where subadult trees optimized photosynthetic efficiency through compact architecture and enhanced hydraulic safety, while seedlings prioritized vertical space occupation. Our findings revealed that heteromorphic twigs play a pivotal role in modular trait coordination, providing mechanistic insights into P. euphratica’s adaptation to extreme aridity throughout its lifespan. Full article

Understanding the feeding ecology and habitat use of vulnerable shark species is crucial for effective conservation. This study focuses on two large filter-feeding sharks, the megamouth shark (Megachasma pelagios) and whale shark (Rhincodon typus), in Northwestern Pacific waters. Stable isotope analysis (δ¹³C and δ¹⁵N) was conducted on white muscle samples (n = 91) of M. pelagios and fin clips (n = 90) of R. typus, collected via large-mesh drift nets and set nets in Taiwanese waters. In this study, we investigated feeding strategies, ontogenetic dietary shifts, habitat use, and isotopic niche variation in both species. For R. typus, the observed positive correlation between δ¹³C and δ¹⁵N supports the previously proposed active suction filter feeding, as well as implying both a diet with an increasing proportion of higher trophic level prey and an ontogenetic shift. In contrast, M. pelagios displayed a negative correlation, consistent with a previous study associating such patterns with primary or secondary consumers, further aligning with its reported planktonic prey dominance. Both species had increasing δ¹³C with growth, signifying a shift to nutrient-rich habitats. Only R. typus exhibited ontogenetic diet changes (δ¹⁵N). SIBER (Stable Isotope Bayesian Ellipses in R) analysis revealed distinct feeding strategies and habitat use between the two species, potential sexual segregation, and wider isotopic niche widths for males in both species. The findings underscore the importance of considering species-specific behaviors and sex-based differences in conservation strategies. Full article

The trophic spectrum provides a useful method to investigate the trophic structure of fish communities. However, ontogenetic shifts in diet can cause variations in the trophic level with body size, thereby influencing the trophic structure of fish communities. In this study, we investigated the effect of ontogenetic dietary shifts on the trophic structure of fish communities in Haizhou Bay based on trophic spectra and trophic indicators calculated under different scenarios of functional group classification. The results showed that the size threshold of ontogenetic dietary shifts was a viable basis for functional group classification. The biomass of fishes at trophic levels 3.4–3.8 was lower when ontogenetic dietary shifts were considered, which can influence the intensity of top–down control and hinder the formulation of harvest strategies. Ontogenetic dietary shifts can also redistribute the biomass of fishes across trophic levels, thereby regulating the trophic structure of fish communities. Different responses of trophic indicators to ontogenetic dietary shifts were identified, with high trophic indicator (HTI) being the most appropriate indicator reflecting the effect of ontogenetic dietary shifts in the trophic structure. This study provides a feasible way to optimize the trophic spectrum for elucidating the trophic structure of fish communities. And we recommend that ontogenetic dietary shifts should be considered and valued in fishery management. Full article

Big head croaker (Collichthys lucidus) is a dominant fish species in the Yangtze River estuary, with significant economic and ecological value in the local ecosystem. In this study, the dietary composition of big head croaker in the Yangtze River estuary from 2022 to 2023 was determined using stomach content analysis. Statistical methods such as cluster analysis and canonical correspondence analysis were also applied to study the ontogenetic variation in the feeding habits of big head croaker and their relationships with environmental factors. The results indicated that big head croaker in the Yangtze River estuary fed primarily on 15 prey groups and 33 prey species. Copepods were the dominant prey group, followed by mysids, shrimp, and fish. The dominant prey species included Acanthomysis longirostris, Neomysis awatschensis, and Calanus sinicus. Compared with historical studies, the proportion of large prey such as fish and crustaceans in the diet of big head croaker has increased since the implementation of the “10-Year Fishing Ban” on the Yangtze River, which reflects the improved aquatic habitat for organisms in the Yangtze River estuary to some extent. The feeding habits of big head croaker exhibited clear ontogenetic and seasonal variations. The empty stomach rate gradually decreased as the body size of big head croaker increased and their main prey shifted from small individuals such as Acetes chinensis and A. longirostris to larger individual fishes and Brachyura. In addition, big head croaker primarily fed on N. awatschensis in spring, A. longirostris in summer and autumn, and Acrocalanus gibber in winter. Canonical correspondence analysis indicated that salinity and length were the factors most strongly correlated with the feeding habits of big head croaker, followed by latitude and longitude. Full article

Echis species (saw-scaled vipers) are WHO Category 1 medically significant venomous snakes with potent procoagulant venoms, which cause lethal venom-induced consumptive coagulopathy in human victims. Despite clinical presentations of bites varying significantly between individuals within the same species, the contribution of age-related changes in the venom biochemistry has not been investigated. This study investigated the ontogenetic changes in Echis pyramidum pyramidum venom and its impact on therapeutic efficacy. The efficacy of various antivenoms (Echitab, Echitab+ ICP, Inosan MENA, Inosan Pan African, and SAVP-Echis) was tested against both venom phenotypes. While both neonate and adult venoms were procoagulant, there were differences in the underlying biochemistry. Neonate venom was found to potently pathophysiologically activate Factor VII and Factor X, and to a lesser degree Factor XII. In contrast, adult venom was a slower clotter, less potent in activating FVII, equipotent with neonate venom on FXII, and inactive on FX. This is the first documentation of FVII and FXII activation for any Echis venom. The significant ontogenetic toxicological variations in Echis species were shown to impact antivenom efficacy. Among the tested antivenoms, SAVP-Echis was the most effective against both venom phenotypes, with adult venom being better neutralized. These findings suggest the need for a reconsideration of venom mixture selection in antivenom production through the inclusion of neonate venom. Additionally, the results indicate differential ontogenetic predatory ecology, providing a foundation for future natural history investigations. Full article

Background/Objectives: Omeprazole is widely used for managing gastrointestinal disorders like GERD, ulcers, and H. pylori infections. However, its use in pediatrics presents challenges due to drug interactions (DDIs), metabolic variability, and safety concerns. Omeprazole’s pharmacokinetics (PK), primarily influenced by CYP2C19 metabolism, is affected by ontogenetic changes in enzyme expression, complicating dosing in children. Methods: This study aimed to develop and validate a physiologically based pharmacokinetic (PBPK) model for omeprazole and its metabolites to predict age-related variations in metabolism and response. Results: The PBPK model successfully predicted exposure to parent and metabolites in adults and pediatrics, incorporating competitive and mechanism-based inhibition of CYP2C19 and CYP3A4 by omeprazole and its metabolites. By accounting for age-dependent metabolic pathways, the model enabled priori predictions of omeprazole exposure in different age groups. Linking PK to the pharmacodynamics (PD) model, we described the impact of age-related physiological changes on intragastric pH, the primary outcome for proton pump inhibitors efficacy. Conclusions: The PBPK-PD model allowed for the virtual testing of dosing scenarios, providing an alternative to clinical studies in pediatrics where traditional DDI studies are challenging. This approach offers valuable insights for accurate dosing recommendations in pediatrics, accounting for age-dependent variability in metabolism, and underscores the potential of PBPK modeling in guiding pediatric drug development. Full article

Based on allometric theory and scaling laws, numerous mathematical models have been proposed to study ontogenetic growth patterns of animals. Although deterministic models have provided valuable insight into growth dynamics, animal growth often deviates from strict deterministic patterns due to stochastic factors such as genetic variation and environmental fluctuations. In this study, we extend a general model for ontogenetic growth proposed by West et al. to stochastic models for ontogenetic growth by incorporating stochasticity using white noise. According to data variance fitting for stochasticity, we propose two stochastic models for ontogenetic growth, one is for determinate growth and one is for indeterminate growth. To develop a universal stochastic process for ontogenetic growth across diverse species, we approximate stochastic trajectories of two stochastic models, apply random time change, and obtain a geometric Brownian motion with a multiplier of an exponential time factor. We conduct detailed mathematical analysis and numerical analysis for our stochastic models. Our stochastic models not only predict average growth well but also variations in growth within species. This stochastic framework may be extended to studies of other growth phenomena. Full article

This study examined the pathophysiological effects of venoms from neonate and adult specimens of the viperid snake Macrovipera lebetina obtusa, focusing on their ability to activate various blood clotting factors in human plasma. All venoms exhibited strong procoagulant properties. In concentration–response tests, the clotting potency of the neonate venoms fell within the range of their parents’ maximum clotting velocities and areas under the curve. Intriguingly, females were more potent than males within each age group, but this requires a larger sample size to confirm. Antivenom neutralization efficacy was equipotent across age groups. The venoms potently activated Factor X (FX) robustly, consistent with previous knowledge of this genus. For the first time, the ability to activate Factors VII (FVII) and XII (FXII) was identified in this genus, with FXII exhibiting particularly strong activation. The study found no significant ontogenetic variation in procoagulant venom potency on human plasma, convergent with the Daboia genus, the other large-bodied lineage within the Palearctic viperid clade. However, the activation of FXII and FVII reveals previously undocumented pathways in the procoagulant activity of these venoms, contributing to the broader understanding of venom evolution and its clinical impacts. These findings have implications for venom biodiscovery and the development of antivenoms, highlighting the complexity of clotting factor activation beyond traditional investigations that have myopically focused upon FX and prothrombin pathways, thereby underscoring the importance of exploring additional clotting factors. Full article

The Eastern Long-Nosed Viper (Vipera ammodytes meridionalis) is considered one of the most venomous snakes in Europe. However, it is unknown whether ontogenetic variation in venom effects occurs in this subspecies and how this may impact antivenom efficacy. In this study, we compared the procoagulant activities of V. a. meridionalis venom on human plasma between neonate and adult venom phenotypes. We also examined the efficacy of three antivenoms—Viperfav, ViperaTAb, and Inoserp Europe—across our neonate and adult venom samples. While both neonate and adult V. a. meridionalis venoms produced procoagulant effects, the effects produced by neonate venom were more potent. Consistent with this, neonate venom was a stronger activator of blood-clotting zymogens, converting them into their active forms, with a rank order of Factor X >> Factor VII > Factor XII. Conversely, the less potent adult venom had a rank order of FXII marginally more activated than Factor VII, and both much more so than Factor X. This adds to the growing body of evidence that activation of factors besides FII (prothrombin) and FX are significant variables in reptile venom-induced coagulopathy. Although all three examined antivenoms displayed effective neutralization of both neonate and adult V. a. meridionalis venoms, they generally showed higher efficacy on adult venom than on neonate venom. The ranking of antivenom efficacy against neonate venom, from the most effective to the least effective, were Viperfav, Inoserp Europe, ViperaTAb; for adult venom, the ranking was Inoserp Europe, Viperfav, ViperaTAb. Our data reveal ontogenetic variation in V. a meridionalis, but this difference may not be of clinical concern as antivenom was effective at neutralizing both adult and neonate venom phenotypes. Regardless, our results highlight a previously undocumented ontogenetic shift, likely driven by the documented difference in prey preference observed for this species across age classes Full article

The relationship between diet and behavior is essential to understanding an animal’s strategies to obtain food, considering ontogenical changes. In reptiles, there is a relationship between the length of the individual and the size of the prey it consumes. Studies have focused on the ontogenetic changes in reptile diets from hatchling to adult, but only a few studies have focused on the transition from hatchling to juvenile. We aimed to describe and analyze the composition, variation, diversity, and overlap in the diet of hatchling Morelet’s crocodiles (Crocodylus moreletii) for three size intervals during the hatchling–juvenile transition. We captured 31 hatchling Morelet’s crocodiles in an urbanized lagoon in Tabasco. We performed stomach-flushing to determine the diet. Additionally, we estimated the volume, frequency of occurrence, and relative importance of diet items and analyzed the relationship between prey type and the total length of the individuals. The diversity of the hatchling prey suggests a generalist diet. We observed two items not previously described in the diet of hatchling crocodiles. In addition, we found differences in diet between the initial and final size intervals, as increases in the length of prey appeared that they did not consume when they were hatchlings. Our results contribute new information to the dietary changes that occur during the hatchling–juvenile transition. Full article

Nursery habitats play a significant role in completing fish life cycles, and they are now recognized as essential habitats. Monthly variations in nursery ground distributions of Larimichthys polyactis were investigated in the southern Yellow Sea in 2019. Bayesian hierarchical models with integrated nested Laplace approximation were utilized to model the preferential nursery habitats of L. polyactis larvae. The study analyzed the spatial and temporal distributions of the larvae and juveniles based on three environmental variables: sea surface temperature, sea surface salinity, and depth. Additionally, this study examined the utilization of habitats by different fish life stages and ontogenetic shifts. A total of 3240 individuals were collected from April to June, with the peak occurring in May (0.05 ind./m³), and the distribution areas varied between different months. The prediction of the model reveals the ecological adaptability of L. polyactis to temperature variations. The optimal temperature for L. polyactis density ranges from 12.5 °C to 16.5 °C in April and 16.5 °C to 17.5 °C in May, demonstrating a broad temperature tolerance for L. polyactis survival. In addition, there are variations in distribution patterns among different developmental stages. Larimichthys polyactis spawn in the inshore and nearshore waters, and after hatching, larvae in the pre-flexion stage tend to remain aggregated near the spawning beds. However, larvae in the advanced development stage (post-flexion) and juveniles move towards the sandy ridge habitats along the coast and start to migrate offshore in June. This study provides valuable insights for the effective management of fishery resources in the area and can be utilized to identify marine areas with specific habitat features that require conservation. Full article

The aim of this study was to explore the connection between growth and feeding ecology and mercury (Hg) levels in Japanese anchovy (Engraulis japonicus). We measured the amounts of Hg and stable carbon and nitrogen isotopes in the muscle of 143 Japanese anchovy specimens obtained from the open seas of the Northwest Pacific Ocean (39°2′ N~42°30′ N, 154°02′ E~161°29′ E) between June and July 2021. The results showed that there were significant differences (p < 0.05) in the δ¹³C and δ¹⁵N values of Japanese anchovies across all body length groups. As individuals grew, δ¹³C tended to decrease first and then increase, and δ¹⁵N tended to gradually increase. The standard ellipse corrected area showed an increasing and subsequently decreasing pattern with growth. It reached its greatest value (0.80) in the 111–120 mm group. Compared to the body length group of 91–120 mm, the niche overlap decreased for the 121–140 mm group in Japanese anchovy. Hg levels increased gradually with body length. Linear regression models revealed a positive correlation between Hg levels and δ¹³C in fish. Hg levels increased gradually, while δ¹⁵N remained relatively constant in the 7–9‰ range. In our study, a distinct shift in diet was observed for Japanese anchovy with increasing body length, and the differences in diet among life stages could be responsible for the changes in Hg levels. Full article