Adult Size Research Articles

Population parameters and conservation implications for one of the world's rarest marine fishes, the red handfish (Thymichthys politus).

Population estimates are required for effective conservation of many rare marine species, but can be difficult to obtain. The critically endangered red handfish (Thymichthys politus) is a coastal anglerfish known only from two fragmented populations in southeast Tasmania, Australia. It is at a high risk of extinction due to low numbers, loss of habitat, and the impacts of climate change. To aid conservation efforts, we provide the first empirical population size estimates of red handfish and investigate other important aspects of the species' life history, such as growth, habitat association, and movement. We surveyed both red handfish local populations via underwater visual census on scuba over 3 years and used photographic mark-recapture techniques to estimate biological parameters. In 2020, the local adult population size was estimated to be 94 (95% confidence interval [CI] 40-231) adults at one site, and 7 (95% CI 5-10) at the other site, suggesting an estimated global population of 101 adults. Movement of individuals was extremely limited at 48.5 m (± 77.7 S.D.) per year. We also found evidence of declining fish density, a declining proportion of juveniles, and increasing average fish size during the study. These results provide a serious warning that red handfish are likely sliding toward extinction, and highlight the urgent need to expand efforts for ex situ captive breeding to bolster numbers in the wild and maintain captive insurance populations, and to protect vital habitat to safeguard the species' ongoing survival in the wild.

Asymmetric environmental selection on intraspecific body size in Collembola communities along an elevational gradient in northern Japan

Body size is a crucial functional trait that influences the environmental filtering processes of animal communities. However, the role of intraspecific variations in soil invertebrate communities remains poorly understood. In this study, we investigated the influence of environmental changes on intraspecific body size variations in Collembola communities along an elevational gradient in northern Japan, using potential body length in the literature cited and realized body length actually measured. Our hypothesis posits that environmental conditions selectively filtered out smaller nymphs while sparing larger adults of Collembola, as stress tolerance, survival and mortality are directly influenced by body size in response to environmental severity. Calculating size quantiles based on observed realized individual body lengths, we found a stable size hierarchy among species across elevational sites. Species composition was significantly related with elevational gradient, with community-weighted means of smaller quantiles in body length increasing at higher elevations, while those of larger quantiles and adult body size remained unaffected. This suggests that environmental filtering predominantly influences the body size of smaller individuals, such as nymphs, but not larger adults within species. Our findings reveal asymmetric size selection among different life stages in soil animal communities.

Plasticity of Life-History Traits and Adult Fitness of Fall Webworm in Relation to Climate Change.

Temperature is an important environmental factor influencing the life-history traits of ectotherms. This study investigated the effects of larval-rearing temperature (21, 23, 25, and 27 °C) on the life-history traits and adult fitness of the fall webworm, Hyphantria cunea, an economically important invasive pest of China. With the increase in temperature during the larval stage, the larval developmental duration was significantly shortened, and the body mass was significantly increased, as was that of the body mass and size of pupae. The carbohydrate and lipid content of pupae significantly decreased with increasing larval-rearing temperature, whereas the protein content significantly increased. Adult body size and egg production increased significantly with increasing larval-rearing temperature, whereas there was no significant difference in egg diameter. These results indicate that H. cunea demonstrates life-history traits plasticity. In addition, the increase in fecundity would maintain a stable population size of H. cunea under higher temperatures. Such characteristics could enable H. cunea to spread to the more southern, warmer areas of China, posing an increased risk to the forestry industry in these regions.

Inaccurate but predictable: Vocal-tract length estimation and gender stereotypes in height perception

Research suggests human listeners are not very accurate in assessing the size of adults from their speech, though they appear to be consistent in their judgments across listeners. Two experiments were conducted to investigate the importance of the higher formants for providing consistent height judgments, how consistent these height judgments are across replications, and the role of f0 and social knowledge in maintaining the stability of apparent speaker height judgments. Listeners were presented with syllables produced by 30 adult male and female speakers, and were asked to identify the word, the gender of the speaker, and the height of the speaker. In a second experiment, listeners were presented with voiced and (synthetic) whispered speech and asked to provide the same responses. Results indicate that speakers use acoustic cues in largely predictable ways, leading to consistent apparent height judgments when averaged across listeners. However, the behavior of individual listeners is unpredictable, and the accuracy of apparent height judgments with respect to veridical heights is low. Finally, results suggest that non-acoustic social knowledge regarding the expected sizes of adult males and females play an important role in the determination of apparent height from speech.

Effects of early exercise training following severe burn injury: a randomized controlled trial.

Despite being a stable component of burn rehabilitation at later stages of recovery, exercise training is not commonly provided during the acute phase of burns. A lack of evidence surrounding its efficacy and safety in severely burned adults has hampered its implementation in acute burn care. The aim of this study was to investigate the capacity of early exercise training to modulate parameters of postburn muscle wasting and quality of life. Adults <65years of age with burns ≥40% total burn surface area (TBSA) were randomly allocated to either receive early exercise (n = 29) in addition to standard care or standard care alone (n = 29). Early exercise involved resistance and aerobic training, which commenced as early as possible and lasted for a duration of 6 to 12 weeks, in line with burn center length of stay. Ultrasound-derived quadriceps muscle layer thickness (QMLT) and rectus femoris cross-sectional area (RF-CSA), lower limb muscle force, Eurocol Quality of Life-5 Dimensions and Burn Specific Health Scale Brief (BSHS-B) were assessed 6 and 12 weeks after baseline. Mixed models were fitted to compare between-group changes over time. A total of 58 adults [42 (95% confidence interval 40-45) years old; 40-94% TBSA range, 86% previously mechanically ventilated] participated in this study. Exercise commenced 7 days [IQR (interquartile range) 5-9] after burn center admission with an attendance rate of 93%. Allocation to the exercise group had a protective effect on the loss of muscle size from baseline to 6 weeks of follow-up (QMLT: β-coefficient: 0.05cm, p = 0.010; RF-CSA: β-coefficient: 0.05 cm2, p = 0.045), and resulted in an improved recovery from 6 to 12 weeks (QMLT: β-coefficient: 0.04cm, p = 0.01; RF-CSA: β-coefficient: 0.06 cm2, p < 0.001). Muscle force increased significantly more in the exercise group than in the control group (β-coefficient: 3.102N, p < 0.001) between 6 and 12 weeks. Besides a marginally significant effect for the BSHS-B domains 'affect' and 'interpersonal relationships' between 6 and 12 weeks, no benefits were observed in the other assessed quality-of-life measures. No serious adverse events were reported in the exercise group. The results of this study support the use of early exercise training as a feasible and efficacious therapeutic strategy to manage burn-related changes in muscle size and strength in adults with acute severe burn injury.

Patterned apoptosis has an instructive role for local growth and tissue shape regulation in a fast-growing epithelium

What regulates organ size and shape remains one fundamental mystery of modern biology. Research in this area has primarily focused on deciphering the regulation in time and space of growth and cell division, while the contribution of cell death has been overall neglected. This includes studies of the Drosophila wing, one of the best-characterized systems for the study of growth and patterning, undergoing massive growth during larval stage and important morphogenetic remodeling during pupal stage. So far, it has been assumed that cell death was relatively neglectable in this tissue both during larval stage and pupal stage, and as a result, the pattern of growth was usually attributed to the distribution of cell division. Here, using systematic mapping and registration combined with quantitative assessment of clone size and disappearance as well as live imaging, we outline a persistent pattern of cell death and clone elimination emerging in the larval wing disc and persisting during pupal wing morphogenesis. Local variation of cell death is associated with local variation of clone size, pointing to an impact of cell death on local growth that is not fully compensated by proliferation. Using morphometric analyses of adult wing shape and genetic perturbations, we provide evidence that patterned death locally and globally affects adult wing shape and size. This study describes a roadmap for precise assessment of the contribution of cell death to tissue shape and outlines an important instructive role of cell death in modulating quantitatively local growth and morphogenesis of a fast-growing tissue.

Early stress variation reflected in adult vertebral neural canal size within a medieval silver-mining population from Kutná Hora (Czech Republic)

Early stress variation reflected in adult vertebral neural canal size within a medieval silver-mining population from Kutná Hora (Czech Republic)

Causal associations of birth body size and adult body size with systemic lupus erythematosus: a bidirectional mendelian randomization study.

Body size is associated with the onset of systemic lupus erythematosus (SLE). However, the evidence for this association is inconclusive. In this study, we aimed to investigate the causal relationship between body size and SLE. We performed a bidirectional Mendelian randomization (MR) analysis that utilized summary statistics sourced from genome-wide association study (GWAS) data obtained from the IEU Open GWAS project website. The inverse variance weighting (IVW) method was used to evaluate the causality, and four additional MR methods were used to supplement the IVW results. Sensitivity analyses were performed using the Cochran's Q test, MR-Egger regression, leave-one-out analysis, and the Mendelian Randomization Pleiotropy RESidual Sum and Outlier (MR-PRESSO) global test. In the forward direction analysis, the IVW model demonstrated that birth weight (odds ratio (OR), 1.811; 95% confidence interval (CI), 1.174-2.793; p < 0.05) and adult height (OR, 1.225; 95% CI, 1.046-1.434; p < 0.05) were positively associated with SLE. Four additional MR scans were performed parallel to the IVW results. Conversely, SLE was a weak causal factor for increased height (OR, 1.010; 95% CI, 1.002-1.018; p < 0.05) using the IVW method. Heterogeneity, MR-Egger intercept, and leave-one-out analyses indicated that the results were robust. The MR-PRESSO suggested the presence of pleiotropy. Following the exclusion of instrumental variables (IVs) inducing pleiotropy, subsequent MR analysis yielded consistent results, thereby reinforcing the robustness of our findings. Positive causal associations were observed between birth weight, adult height, and SLE incidence. In the reverse analysis, SLE was a weak causal factor for adult height.

Brain size scaling through development in the whitelined sphinx moth (Hyles lineata) shows mass and cell number comparable to flies, bees, and wasps

Factors regulating larval growth and determinants of adult body size are described for several holometabolous insects, but less is known about brain size scaling through development. Here we use the isotropic fractionation (“brain soup”) method to estimate the number of brain cells and cell density for the whitelined sphinx moth (Lepidoptera: Hyles lineata) from the first instar through the adult stage. We measure mass and brain cell number and find that, during the larval stages, body mass shows an exponential relationship with head width, while the total number of brain cells increases asymptotically. Larval brain cell number increases by a factor of ten from nearly 8000 in the first instar to over 80,000 in the fifth instar. Brain cell number increases by another factor of 10 during metamorphosis, with the adult brain containing more than 900,000 cells. This is similar to increases during development in the vinegar fly (Drosophila melanogaster) and the black soldier fly (Hermetia illucens). The adult brain falls slightly below the brain-to-body allometry for wasps and bees but is comparable in the number of cells per unit brain mass, indicating a general conservation of brain cell density across these divergent lineages.

Application of dsRNA in the Pine Wood Nematode, Bursaphelenchus xylophilus.

The pine wood nematode Bursaphelenchus xylophilus is one of the most destructive invasive species worldwide, causing the wilting and eventual death of pine trees. Despite recognition of their economic and environmental significance, it has thus far been impossible to study the detailed gene functions of plant parasitic nematodes through conventional forward genetics and transgenic methods. RNA interference (RNAi), as a reverse genetics technology, offers great convenience for studying the functional genes of nematodes, including B. xylophilus. We here outline a protocol for RNAi of the ppm-1 gene in B. xylophilus, which has been reported to play crucial roles in the development and reproduction of other pathogenic nematodes. For RNAi, the T7 promoter was linked to the 5'-terminal of the target fragment by polymerase chain reaction (PCR), and then double-stranded RNA (dsRNA) was synthesized by in vitro transcription. Subsequently, dsRNA delivery was accomplished by soaking nematodes with the dsRNA solution mixed with synthetic neurostimulants. Synchronized eggs, juveniles, and adults of B. xylophilus (approximately 20,000 individuals of each stage) were washed and soaked in dsRNA (0.8μg/mL) with the soaking buffer for 24h in the dark at 25°C. The same quantity of nematodes was placed in the soaking buffer without dsRNA or with green fluorescent protein dsRNA as a control. After soaking, the expression level of the target transcripts was determined by real-time quantitative PCR. The effects of RNAi were then confirmed by microscopic observation of the phenotypes and comparison of the body size of adults among groups. The current protocol can help to progress research to understand the functions of the genes of B. xylophilus and other parasitic nematodes toward developing control strategies through genetic engineering.

Growth assessment of the sea urchin Pseudechinus magellanicus (Temnopleuridae) in coastal habitats of central Patagonia, Argentina

Abstract Pseudechinus magellanicus is an ecologically important and small sea urchin in coastal and nearshore habitats off southern South America. We provide the first growth assessment for the species using tag (calcein) and recapture procedures in central Patagonia (Argentina). The individual growth rate of P. magellanicus ranged 0.05–1.3 mm year−1. The Brody–Bertalanffy and Richards growth models provided asymptotic maximum diameters of 29.89 and 26.01 mm, respectively. Both models yielded low values for the growth constant (k), with 0.046 (Brody–Bertalanffy) and 0.062 (Richards). Maximum instantaneous growth rate was estimated at 1.36 mm year−1 for the Brody–Bertalanffy model, and 2.69 mm year−1 for the Richards model. Model selection (corrected Akaike information criterion) showed a slight better fit for the Brody–Bertalanffy growth model compared to the Richards model. A significant variability in growth was observed within the studied population, which can be attributed to genetic factors and micro-environmental effects. P. magellanicus displays a combination of slow growth and small body size, with the lowest recorded growth performance index (θ = 3.72) recorded so far in sea urchins. The species has a long lifespan, with the most common adult sizes estimated to range from 15 to 21 years according to the Brody–Bertalanffy model. Due to the broad geographic distribution and occupation of contrasting habitats, further studies are necessary to explore growth of P. magellanicus under different environmental conditions and/or along a bathymetric gradient.

Anomalous pigmentation in a dusky dolphin Lagenorhynchus obscurus from Golfo Nuevo, Argentinian Patagonia

Anomalous pigmentation conditions occur with low frequency in marine mammals. Here is presented the first known record and resighting of a hypo-pigmented all-white dusky dolphin from Golfo Nuevo off Península Valdés, Argentinian Patagonia. The anomalously pigmented Lagenorhynchus obscurus was observed three times between 2016 and 2018. Images suggest that this could be a case of a leucistic dusky dolphin, apparently a single individual. The hypo-pigmented individual was estimated to have reached adult body size, and was probably sexually mature. More research is required for a proper understanding of the effect on behavioral, ecological and physiological conditions.

A new species of terrestrially-nesting fanged frog (Anura: Dicroglossidae) from Sulawesi Island, Indonesia.

Herein, we describe a new species of terrestrially-nesting fanged frog from Sulawesi Island, Indonesia. Though male nest attendance and terrestrial egg deposition is known in one other Sulawesi fanged frog (Limnonectes arathooni), the new species exhibits a derived reproductive mode unique to the Sulawesi assemblage; male frogs guard one or more clutches of eggs festooned to leaves or mossy boulders one to two meters above small slow-moving streams, trickles, or seeps. This island endemic has thus far been collected at three sites on Sulawesi: one in the Central Core of the island, and two on the Southwest Peninsula-south of the Tempe Depression (a major biogeographical boundary). The new Limnonectes has the smallest adult body size among its Sulawesi congeners-with a maximum snout-vent length of about 30 millimeters. Beyond its unique reproductive behavior and body size, the species is further diagnosed on the basis of advertisement call and genetic distance from sympatric fanged frogs. The discovery and description of the new species highlights the remarkable reproductive trait diversity that characterizes the Sulawesi fanged frog assemblage despite that most species in this radiation have yet to be formally described.

Association between dietary diversity and cognitive impairment in community-dwelling older adults.

The present study aimed to examine whether dietary diversity is associated with cognitive impairment, including mild cognitive impairment (MCI), in community-dwelling older Japanese adults. This cross-sectional study was carried out in a general community setting. MCI and global cognitive impairment (GCI) were assessed using the Mini-Mental State Examination and National Center for Geriatrics and Gerontology-Functional Assessment Tool, which are multicomponent neurocognitive tests that include memory attention, executive function and processing speed. Dietary diversity was assessed using the diet variety score. The diet variety score assessed the 1-week consumption frequency of 10 food groups, and either 0 or 1 point was allocated to each category based on the following responses: (i) "eat almost every day" (1 point); and (ii) "not eaten almost daily" (0 points). Older adults with a diet variety score of ≥3 points were defined as having high dietary diversity. Data included 8987 older adults (mean age 73.9 ± 5.5 years; men 44.3%). The overall prevalences of MCI and GCI were 17.1% (n = 1538) and 8.4% (n = 753), respectively. The proportion of patients with a high dietary diversity was 69.9% (n = 6286). Multinomial logistic regression analysis revealed high dietary diversity was associated with MCI (OR 0.83, 95% CI 0.73-0.94) and GCI (OR 0.77, 95% CI 0.65-0.92) after adjusting for covariates. This study had a large sample size of older Japanese adults, and showed that high dietary diversity was associated with a lower proportion of MCI and GCI among older adults. Geriatr Gerontol Int 2024; 24: 75-81.

Relationships among development, growth, body size, reproduction, aging, and longevity - trade-offs and pace-of-life

Relationships of growth, metabolism, reproduction, and body size to the biological process of aging and longevity have been studied for decades and various unifying “theories of aging” have been proposed to account for the observed associations. In general, fast development, early sexual maturation leading to early reproductive effort, as well as production of many offspring, have been linked to shorter lifespans. The relationship of adult body size to longevity includes a remarkable contrast between the positive correlation in comparisons between different species and the negative correlation seen in comparisons of individuals within the same species. We now propose that longevity and presumably also the rate of aging are related to the “pace-of-life.” A slow pace-of-life including slow growth, late sexual maturation, and a small number of offspring, predicts slow aging and long life. The fast pace of life (rapid growth, early sexual maturation, and major reproductive effort) is associated with faster aging and shorter life, presumably due to underlying trade-offs. The proposed relationships between the pace-of-life and longevity apply to both inter- and intra-species comparisons as well as to dietary, genetic, and pharmacological interventions that extend life and to evidence for early life programming of the trajectory of aging. Although available evidence suggests the causality of at least some of these associations, much further work will be needed to verify this interpretation and to identify mechanisms that are responsible.

Child-to-adult body size change and risk of type 2 diabetes and cardiovascular disease.

Childhood overweight increases the risk of type 2 diabetes and cardiovascular disease in adulthood. However, the impact of childhood leanness on adult obesity and disease risk has been overlooked. We examined the independent and combined influences of child and adult body size on the risk of type 2 diabetes and cardiovascular disease. Data from the UK Biobank on 364,695 individuals of European ancestry and free of type 2 diabetes and cardiovascular disease were divided into nine categories based on their self-reported body size at age 10 and measured BMI in adulthood. After a median follow-up of 12.8 years, 33,460 individuals had developed type 2 diabetes and/or cardiovascular disease. We used Cox regression models to assess the associations of body size categories with disease incidence. Individuals with low body size in childhood and high body size in adulthood had the highest risk of type 2 diabetes (HR 4.73; 95% CI 4.50, 4.99), compared to those with average body size in both childhood and adulthood. This was significantly higher than the risk in those with high body size in both childhood and adulthood (HR 4.05; 95% CI 3.84, 4.26). By contrast, cardiovascular disease risk was determined by adult body size, irrespective of childhood body size. Low body size in childhood exacerbates the risk of type 2 diabetes associated with adult obesity but not the risk of cardiovascular disease. Thus, promoting healthy weight management from childhood to adulthood, among lean children, is crucial.

From Empowerment to Exploitation: Predicting Positive and Negative Associations with the Exchange of Sexual Services for Payment

AbstractFew existing studies have delved into individual-level attitudes towards the exchange of sexual services for payment, leaving a significant gap in our understanding. Various studies have speculated about how certain demographic factors and attitudes may shape people's perceptions of causes and consequences relating to such exchanges, but none have directly investigated this topic. To bridge this gap, we predict individual-level associations between the exchange of sexual services for payment and positive and negative concepts. Using an original survey involving a substantial sample size of adults in the U.S. (n = 611), we examine the extent to which respondents associate these exchanges with sexual freedom, companionship, women's empowerment, poverty, women's exploitation, and human trafficking. Our study reveals some compelling results. When predicting attitudes towards the exchange of sexual services for payment, we find that women exhibit a stronger association with the negative concepts than men. Furthermore, individuals who view the exchange of sexual services for payment as socially acceptable are more likely to have stronger associations with the positive concepts. Surprisingly, the acceptability of exchanging sexual services for payment has no discernable impact on association with the negative concepts. The results add to our understanding of how the public perceives the exchange of sexual services for payment. A more nuanced understanding of public perception can foster constructive dialogues and debates, allowing for a more comprehensive exploration of potential policy solutions.

Activation of immune defences against parasitoid wasps does not underlie the cost of infection.

Parasites reduce the fitness of their hosts, and different causes of this damage have fundamentally different consequences for the evolution of immune defences. Damage to the host may result from the parasite directly harming its host, often due to the production of virulence factors that manipulate host physiology. Alternatively, the host may be harmed by the activation of its own immune defences, as these can be energetically demanding or cause self-harm. A well-studied model of the cost of infection is Drosophila melanogaster and its common natural enemy, parasitoid wasps. Infected Drosophila larvae rely on humoral and cellular immune mechanisms to form a capsule around the parasitoid egg and kill it. Infection results in a developmental delay and reduced adult body size. To disentangle the effects of virulence factors and immune defences on these costs, we artificially activated anti-parasitoid immune defences in the absence of virulence factors. Despite immune activation triggering extensive differentiation and proliferation of immune cells together with hyperglycaemia, it did not result in a developmental delay or reduced body size. We conclude that the costs of infection do not result from these aspects of the immune response and may instead result from the parasite directly damaging the host.

The evolution of human altriciality and brain development in comparative context.

Human newborns are considered altricial compared with other primates because they are relatively underdeveloped at birth. However, in a broader comparative context, other mammals are more altricial than humans. It has been proposed that altricial development evolved secondarily in humans due to obstetrical or metabolic constraints, and in association with increased brain plasticity. To explore this association, we used comparative data from 140 placental mammals to measure how altriciality evolved in humans and other species. We also estimated how changes in brain size and gestation length influenced the timing of neurodevelopment during hominin evolution. Based on our data, humans show the highest evolutionary rate to become more altricial (measured as the proportion of adult brain size at birth) across all placental mammals, but this results primarily from the pronounced postnatal enlargement of brain size rather than neonatal changes. In addition, we show that only a small number of neurodevelopmental events were shifted to the postnatal period during hominin evolution, and that they were primarily related to the myelination of certain brain pathways. These results indicate that the perception of human altriciality is mostly driven by postnatal changes, and they point to a possible association between the timing of myelination and human neuroplasticity.

Resurrection of genus Phocanema Myers, 1959, as a genus independent from Pseudoterranova Mozgovoĭ, 1953, for nematode species (Anisakidae) parasitic in pinnipeds and cetaceans, respectively.

Species of the genus Pseudoterranova, infect kogiid cetaceans and pinnipeds. However, there is mounting molecular evidence that those from cetaceans and pinnipeds are not congeneric. Here, we provide further evidence of the non-monophyly of members of Pseudoterranova from phylogenetic analyses of the conserved nuclear LSU rDNA gene, entire ITS rDNA region and mtDNA cox2 gene, and identify morphological characters that may be used to distinguish the members of the two clades. We propose the resurrection of the genus Phocanema, with Ph. decipiens (sensu stricto) as the type species, to encompass Ph. decipiens, Ph. azarasi, Ph. bulbosa, Ph. cattani and Ph. krabbei, all parasites of pinnipeds. We propose to restrict the conception of genus Pseudoterranova, which now harbours two species infecting kogiid whales; Ps. kogiae (type species) and Ps. ceticola. Members of the genera Phocanema and Pseudoterranova differ by the shape and orientation of the lips, relative tail lengths, adult size, type of final host (pinniped vs. cetacean) and phylogenetic placement based on nuclear rDNA and mtDNA cox2 sequences.