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Holistic insect monitoring needs scalable techniques to overcome taxon biases, determine species abundances, and gather functional traits for all species. This requires that we address taxonomic impediments and the paucity of data on abundance, biomass and functional traits. We here outline how these data deficiencies could be addressed at scale. The workflow starts with large-scale barcoding (megabarcoding) of all specimens from mass samples obtained at biomonitoring sites. The barcodes are then used to group the specimens into molecular operational taxonomic units that are subsequently tested/validated as species with a second data source (e.g. morphology). New species are described using barcodes, images and short diagnoses, and abundance data are collected for both new and described species. The specimen images used for species discovery then become the raw material for training artificial intelligence identification algorithms and collecting trait data such as body size, biomass and feeding modes. Additional trait data can be obtained from vouchers by using genomic tools developed by molecular ecologists. Applying this pipeline to a few samples per site will lead to greatly improved insect monitoring regardless of whether the species composition of a sample is determined with images, metabarcoding or megabarcoding. This article is part of the theme issue 'Towards a toolkit for global insect biodiversity monitoring'. [ABSTRACT FROM AUTHOR]

Global pollinator decline urgently requires effective methods to assess their trends, distribution and behaviour. Passive acoustics is a non-invasive and cost-efficient monitoring tool increasingly employed for monitoring animal communities. However, insect sounds remain highly unexplored, hindering the application of this technique for pollinators. To overcome this shortfall and support future developments, we recorded and characterized wingbeat sounds of a variety of Iberian domestic and wild bees and tested their relationship with taxonomic, morphological, behavioural and environmental traits at inter- and intra-specific levels. Using directional microphones and machine learning, we shed light on the acoustic signature of bee wingbeat sounds and their potential to be used for species identification and monitoring. Our results revealed that frequency of wingbeat sounds is negatively related with body size and environmental temperature (between-species analysis), while it is positively related with experimentally induced stress conditions (within-individual analysis). We also found a characteristic acoustic signature in the European honeybee that supported automated classification of this bee from a pool of wild bees, paving the way for passive acoustic monitoring of pollinators. Overall, these findings confirm that insect sounds during flight activity can provide insights on individual and species traits, and hence suggest novel and promising applications for this endangered animal group. This article is part of the theme issue 'Towards a toolkit for global insect biodiversity monitoring'. [ABSTRACT FROM AUTHOR]

Establishment of extant terrestrial vertebrate faunas in North America was influenced by a set of factors associated with temporal changes in climate and ecology that operated at different geographic scales. While the biogeography of extant taxa can be inferred from phylogenies, these omit lineages that have gone regionally extinct and for which the only direct evidence is the fossil record. A comprehensive study of anurans from the Late Oligocene of Florida reveals an abundance of fossils referred to Eleutherodactylus. Time-calibrated molecular phylogenies have suggested that this genus originated in the Caribbean in the Early Oligocene and then colonized Central America in the Middle Miocene. Here, we describe the first records of pre-Quaternary fossils referred to Eleutherodactylus from Florida. Results from analysis of inter- and intraspecific variation in anatomy, size, and shape of isolated bones of fossil and extant species suggest that the fossils represent adult individuals with an estimated body size (snout–urostyle length) of 16.8–29.8 mm. We show that Eleutherodactylus was established by the Late Oligocene in North America well before colonizing Central America in the Miocene. We provide, for the first time, evidence of dispersal of amphibians from the Caribbean into North America during the Late Oligocene. [ABSTRACT FROM AUTHOR]

Background: Lower activation of higher threshold (type-II) motor units (MUs) has been suggested in children compared with adults. We examined child–adult differences in discrete MU activation of the flexor carpi radialis (FCR). Methods: Fifteen boys (10.2 ± 1.4 years), and 17 men (25.0 ± 2.7 years) completed 2 laboratory sessions. Following a habituation session, maximal voluntary isometric wrist flexion torque (MVIC) was determined before completing trapezoidal isometric contractions at 70%MVIC. Surface electromyography was captured by Delsys Trigno Galileo sensors and decomposed into individual MU action potential trains. Recruitment threshold (RT), and MU firing rates (MUFR) were calculated. Results: MVIC was significantly greater in men (10.19 ± 1.92 Nm) than in boys (4.33 ± 1.47 Nm) (p < 0.05), but not statistically different after accounting for differences in body size. Mean MUFR was not different between boys (17.41 ± 7.83 pps) and men (17.47 ± 7.64 pps). However, the MUFR–RT slope was significantly (p < 0.05) steeper (more negative) in boys, reflecting a progressively greater decrease in MUFR with increasing RT. Additionally, boys recruited more of their MUs early in the ramped contraction. Conclusion: Compared with men, boys tended to recruit their MUs earlier and at a lower percentage of MVIC. This difference in MU recruitment may explain the greater decrease in MUFR with increasing RT in boys compared with men. Overall, these findings suggest an age-related difference in the neural strategy used to develop moderate–high torque in wrist flexors, where boys recruit more of their MUs earlier in the force gradation process, possibly resulting in a narrower recruitment range. [ABSTRACT FROM AUTHOR]

The ice-associated nematode Theristus melnikovi has a long-distance dispersal throughout the Arctic. However, this species' taxonomic position and phylogenetic relationships remain unresolved. We used an integrative approach of single-specimen barcoding of morphologically identified specimens of T. melnikovi with note on the phylogeny of two new ice-associated species of the family Xyalidae. DNA barcodes (18S and 28S gene markers) were obtained from 13 specimens of T. melnikovi collected from sea ice in the White and Kara Seas. Analysis of the D2D3 region found three genetically distinct lineages of T. melnikovi from the White Sea ice, suggesting that T. melnikovi specimens belong to the cryptic species, with genetic differentiation attributed to limited ice exchange between remote semi-isolated areas and open Arctic seas. The Kara Sea specimens belong to a single species. Our results highlight that using 18S rDNA data alone underestimates species diversity within sympagic nematodes. The barcoded specimens of T. melnikovi could not be distinguished morphologically, as the majority of the sequenced specimens were juveniles (92.3%). Additional comparative analysis of morphological traits was performed on 34 specimens from sea ice in the Barents, White, Kara, and East Siberian Seas, and from sediment in the East Siberian Sea. Our specimens differed from previous descriptions of T. melnikovi by variable body size, amphidial fovea shape, and absence of precloacal supplements and pigment spots. This study contributes to the understanding of the diversity, variability in habitat, and ecology of sympagic nematodes, confirming the need to put together the integration of molecular and morphological methodologies. [ABSTRACT FROM AUTHOR]

Phytosaurs are a group of Upper Triassic semi‐aquatic archosauriform reptiles. Their variable skull morphology forms the foundation of our understanding of their relationships and paleoecology, while only a few studies have focused on demonstrating the existence of postcranial variation. The numbers of vertebrae in the sacrum are thought to vary from two, the plesiomorphic condition for archosauriforms, to three, with the addition of a sacralized dorsal (i.e., dorsosacral) vertebra. In this study, we demonstrate the presence of a sacralized first caudal (i.e., caudosacral) vertebra in a sacrum belonging to Machaeroprosopus mccauleyi. We rule out taphonomic distortion or pathology as explanations for the inclusion of this element in the sacrum, suggesting instead that it occurred through modifications of the same developmental processes that likely produced dorsosacral vertebrae in phytosaurs. Additionally, we show that a dorsosacral vertebra is common in phytosaur specimens from the Chinle Formation and Dockum Group of the southwestern United States and suggest that it may be widespread among phytosaurs. The addition of sacral vertebrae potentially aided adaptation to larger body sizes or more terrestrial lifestyles in certain taxa. [ABSTRACT FROM AUTHOR]

In biogeography, vicariance and long‐distance dispersal are often characterised as competing scenarios. However, they are related concepts, both relying on collective geological, ecological, and phylogenetic evidence. This is illustrated by freshwater fishes, which may immigrate to islands either when freshwater connections are temporarily present and later severed (vicariance), or by unusual means when ocean gaps are crossed (long‐distance dispersal). Marine barriers have a strong filtering effect on freshwater fishes, limiting immigrants to those most capable of oceanic dispersal. The roles of vicariance and dispersal are debated for freshwater fishes of the Greater Antilles. We review three active hypotheses [Cretaceous vicariance, Greater Antilles–Aves Ridge (GAARlandia), long‐distance dispersal] and propose long‐distance dispersal to be an appropriate model due to limited support for freshwater fish use of landspans. Greater Antillean freshwater fishes have six potential source bioregions (defined from faunal similarity): Northern Gulf of México, Western Gulf of México, Maya Terrane, Chortís Block, Eastern Panamá, and Northern South America. Faunas of the Greater Antilles are composed of taxa immigrating from many of these bioregions, but there is strong compositional disharmony between island and mainland fish faunas (>90% of Antillean species are cyprinodontiforms, compared to <10% in Northern Gulf of México and Northern South America, and ≤50% elsewhere), consistent with a hypothesis of long‐distance dispersal. Ancestral‐area reconstruction analysis indicates there were 16 or 17 immigration events over the last 51 million years, 14 or 15 of these by cyprinodontiforms. Published divergence estimates and evidence available for each immigration event suggests they occurred at different times and by different pathways, possibly with rafts of vegetation discharged from rivers or washed to sea during storms. If so, ocean currents likely provide critical pathways for immigration when flowing from one landmass to another. On the other hand, currents create dispersal barriers when flowing perpendicularly between landmasses. In addition to high salinity tolerance, cyprinodontiforms collectively display a variety of adaptations that could enhance their ability to live with rafts (small body size, viviparity, low metabolism, amphibiousness, diapause, self‐fertilisation). These adaptations likely also helped immigrants establish island populations after arrival and to persist long term thereafter. Cichlids may have used a pseudo bridge (Nicaragua Rise) to reach the Greater Antilles. Gars (Lepisosteidae) may have crossed the Straits of Florida to Cuba, a relatively short crossing that is not a barrier to gene flow for several cyprinodontiform immigrants. Indeed, widespread distributions of Quaternary migrants (Cyprinodon, Gambusia, Kryptolebias), within the Greater Antilles and among neighbouring bioregions, imply that long‐distance dispersal is not necessarily inhibitory for well‐adapted species, even though it appears to be virtually impossible for all other freshwater fishes. [ABSTRACT FROM AUTHOR]

Bhilangana granitoid is a batholithic size body exposed in Bhilangana Valley and later thrusted over rocks of Lesser Himalaya. It comprises mylonitized porphyritic granite gneiss, psammitic gneiss, and its variants, containing primary biotite and muscovite, and S-type in nature. Bhilangana granitoid is intruded by basic intrusive. The variation in chemical signatures and associated petrogenetic issues of Bhilangana granitoid are dealt with detailed petrographic, geochemical and mineral chemical study. In the vicinity of basic intrusive, the porphyritic granite gneiss shows enrichment of MgO, whereas its evolved part, psammitic gneiss shows more boron enrichment with the presence of tourmaline nodules surrounded by quartzo-feldspathic rim. The major mineral assemblage in Bhilangana granitoid is quartz–K-feldspar–plagioclase–biotite–muscovite with tourmaline, epidote, zircon, ilmenite, apatite and monazite. The granite is peraluminous with ASI values always >1. Biotite shows variation from Fe-rich siderophyllitic to Mg-rich eastonitic composition, indicating involvement of both Al-rich crustal and Mg-rich mafic sources, inferring source heterogeneity or mixing of felsic-mafic magma. Granitoid melt was buffered below QFM to NNO and partly above HM, indicating a strong reducing to the oxidizing condition of melt. The melt was saturated with the presence of 3.3–6.8 wt.% H2O content. The crystallization temperature of Bhilangana granitoid (TZr) ranges between 697° and 807°C with a solidification pressure of about 2.92–4.31 kbar, implying crystallization at a depth of 8.76–13 km. The presence of greisens assemblage of quartz–mica–tourmaline–epidote, along with the presence of fluorite, is a representative greisens assemblage for Sn–W mineralization. Thus, the Bhilangana granitoid represents the fertile nature and potentiality of Sn–W minerals. Research highlights: Bhilangana granitoid is S-type, peraluminous granitoid, formed by anatexis of crustal material The biotite chemistry reveals the variation in the redox condition and modification in the oxidation state, preserved in the different variant of granite representing the magma mixing or source heterogeneity in protolith. The Bhilangana granitoid has attended the crystallization temperature (TZr) of 697–807 °C under pressure of about 2.92–4.31 kb implying the depth of crystallization of 8.76–13 km. The presence of greisenization favours the potential of Sn–W minerals. The geochemical results shows abnormal enrichment of W and Sn in the Bhilangana granitoid. The Bhilangana granitoid appears to have fertile nature for Sn–W mineral potential. [ABSTRACT FROM AUTHOR]

Wildfire is an increasingly common disturbance in forested landscapes that can drastically alter local habitats. Under current climate change predictions, wildfires are likely to become more frequent and severe. In regions and ecosystems that have historically infrequent fire return intervals, there is little known about how organisms will respond to the more severe and frequent wildfires predicted under climate change. In the southern Appalachian Mountains, USA, fire has been suppressed and severe burns are historically uncommon. This region boasts immense biodiversity and is considered a biological hot spot for diversity in the salamander family Plethodontidae. These species rely upon cool, moist microclimates that may be impacted more by severe fire than by low-intensity wild or prescribed fire. In 2016, the Chimney Tops Two wildfire burned >6000 ha of Great Smoky Mountains National Park, USA, and left a mosaic of burn severity across the landscape. This presented an opportunity to examine how five plethodontid salamander species respond to and recover from a range of burn severity. Even though the landscape had been recovering for 5 yr at the time of study, populations of Plethodon jordani, Plethodon glutinosus spp., Desmognathus wrighti, Desmognathus imitator, and Eurycea wilderae within the burn boundary had lower abundance than those in unburned habitat. In addition, there was a trend of even lower abundances in more severely burned habitat. Evidence of recovery, as indicated by a relationship between population abundance and distance from the burn boundary, was only present for D. imitator. Finally, body size distributions were different between burned and unburned sites for three of the five species and individuals were larger, on average, in burned sites. This work provides insights into how terrestrial salamander populations may respond to the more severe and frequent wildfires predicted under climate change for the southern Appalachian Mountains region. [ABSTRACT FROM AUTHOR]

We collected larvae of the Patch-nosed Salamander, Urspelerpes brucei, and analyzed size-frequency distributions throughout a 12-mo cycle to determine the length of the larval period and size at metamorphosis. The hatchling-size class entered the population across a wide time window, from early winter to late summer, and at a minimal size of 6-mm snout–girdle length (SGL). Examination of both pooled total sample and the samples across six seasonal periods strongly show that the typical larval period is approximately 24 mo, with metamorphosis occurring during late summer to early fall at 18–19 mm SGL. Because oviposition and hatching are extended across several months, it is possible that some animals metamorphose up to 30 mo after hatching. Larval growth in Urspelerpes is 0.5 mm/mo, which is comparable—and even slower—to the slow larval growth seen in all other stream-dwelling plethodontid larvae. Our samples of recently metamorphosed animals and mature adults indicate that males are sexually mature at metamorphosis. This is more difficult to know for females, and we suggest that females may be a mixed group that contains individuals that mature at metamorphosis and individuals that delay maturation for an additional 12 mo. There is no difference in either sex between body size at metamorphosis and at sexual maturation. As in other species in the Spelerpini, the timing of metamorphosis and the timing of sexual maturation appear to be able to evolve independently, with the remarkable result that the early sexual maturation in Urspelerpes results in a tiny adult size despite having a multiyear larval period. [ABSTRACT FROM AUTHOR]

Multispecies assemblages of Appalachian desmognathans have long intrigued ecologists seeking to understand the structure of ecological communities. Body size and life history in this group correlate with the moisture gradient from stream to forest, with large species being more aquatic and progressively smaller ones being ever more terrestrial. Since the work of N.G. Hairston, Sr. in the early 1980s, the prevailing hypothesis has been that predation and competition among desmognathans themselves have been the driving processes in the development and maintenance of the spatial organization along stream sides, with large, aggressive species forcing smaller ones to occupy less favorable terrestrial niches. Decades of research have confirmed that biotic interactions are important. However, evidence from recent studies has not agreed with the idea that biotic interactions are primary. Herein, I have concluded that the prevailing hypothesis fails to reconcile the currently available data. I have presented an alternative hypothesis that an abiotic factor, specifically the relative abundance of water, has been the primary force driving adaptation of species of Desmognathus longitudinally along moisture gradients by way of stream headwaters. Interspecific interactions, though important aspects of the current ecology of these species, are not the underlying drivers of spatial organization along the moisture gradient. I have further generated specific predictions that will enable this hypothesis to be tested. [ABSTRACT FROM AUTHOR]

Amphibian populations, including those of lungless salamanders (Plethodontidae), are susceptible to population declines, especially considering current and predicted climate change. Like many organisms, plethodontid salamanders exhibit reproductive plasticity to maximize population growth in response to environmental conditions. A better understanding of the external causes of reproductive plasticity can provide more accurate population models through the explicit incorporation of such drivers. To this end, we sampled Southern Pygmy Salamanders (Desmognathus wrighti) along a 1345-m elevational gradient in Great Smoky Mountains National Park, USA, to determine the effects of body size and elevation on reproductive investment. Using Bayesian mixed effects models, we assessed whether body size, elevation, or a combination of these factors best explained the probability an individual was gravid, the number of ova in gravid females, and the number of testis lobes in mature males. We found that the interaction of body size and elevation best explained each reproductive measure. Larger females were generally more likely to be gravid, with annual reproduction in fully mature females at low to mid-elevations and roughly biennial reproduction at high elevations. We also found a positive relationship between body size and ova counts at low and mid-elevations, but despite a reduction in reproductive frequency at higher elevations, we found no effect of body size on ova count. In addition, the addition of testis lobes, which has commonly been used as a proxy of age in plethodontid salamanders, occurred at larger body sizes with increasing elevation. Our findings support previous work showing a relationship between body size and reproductive ecology in desmognathine salamanders while providing insight into the complexity of this relationship in the context of elevational clines. Reproductive ecology significantly influences population dynamics; thus, further refinement of these observed patterns and their underlying causes is necessary to advance plethodontid salamander population ecology. [ABSTRACT FROM AUTHOR]

Foraging in animals ranges from a sedentary, ambush mode to more active patterns. Among the plethodontid genus Desmognathus, early observations have indicated that small species and small members of large species may forage more actively than large individuals. Therefore, we tested the hypothesis that foraging within and across the genus depends on body size. We chose species ranging from the largest (D. amphileucus) to the small members of the D. ocoee complex (D. ocoee and D. perlapsus). We also included two species intermediate in size, D. monticola and D. folkertsi. We analyzed foraging of 570 individual salamanders, collecting them at night and determining whether they were foraging while partially within a refuge, indicating an ambush posture, or outside of a refuge in a more active mode. Using replicate streams, we determined that, for each species or species complex, refuged animals had significantly larger snout–vent lengths (SVLs) than individuals outside of a refuge. Moreover, the proportion of individuals foraging in an ambush posture in a refuge increased with mean SVL of the population sampled with 76% of the variance in proportion of search modes being predicted by mean SVL. The results of a replicated laboratory-based experiment did not match the patterns observed in the field, indicating that the trend of larger individuals to remain in refugia is not a simple reflexive response to refugia. However, the trend of larger individuals to forage while remaining in a sedentary, ambush posture in a refuge in resident streams helps to explain ecological and evolutionary patterns within the tribe Desmognathini. [ABSTRACT FROM AUTHOR]

Shifts in mean body size coinciding with environmental change are well documented across animal species and populations, serving as a widespread and complex indicator of climate-change response. In mammal research, identifying and disentangling the potential drivers of these trends (e.g. thermoregulation, resource availability) is hindered by treating adult size as fixed, ignoring morphological changes that occur throughout life in many species. However, observed population-level size trends may reflect underlying shifts in age structure (i.e. change in the proportion of older, potentially larger individuals in the population). Here, we assessed the role of age structure by explicitly evaluating age as a contributor to temporal variation in skull size (a proxy for body size) in 2 carnivorans, Canadian Lynx (Lynx canadensis) and American Marten (Martes americana). Using a series of linear and nonlinear models, we tested age in years (determined by cementum-layer analysis) as a predictor of skull size alongside other factors previously proposed to be important drivers of body-size trends, including population density for lynx and growing season conditions for martens. In both species, age was a significant predictor of skull size indicating a rapid year-to-year increase in young adult size that diminished in later adulthood. However, temporal shifts in age structure alone did not explain the observed changes in size over time, indicating that age structure acts in concert with other as-yet unidentified factors to drive body-size change. By explicitly evaluating the role of age, we can both refine models of temporal body-size trends and gain insights into size change as a signal of underlying demographic shifts—such as age-specific survivorship—providing a more holistic understanding of how mammals are responding to climate change. [ABSTRACT FROM AUTHOR]

Across the globe, fish stocks have been in decline due to industrialization of fisheries resources, overfishing, pollution, and climate change, thereby warranting more fisheries assessments. The floodplain fishery of Tonle Sap Lake near the Kampong Khleang stilted community in the Chamkar Youn village in Cambodia was evaluated by: (1) characterizing fish assemblage structure and function, (2) highlighting temporal differences in fish assemblage, and (3) assessing potential indicators of fishing‐down‐the‐food‐web by the fishery. Fish trap data from the wet season were used to characterize fish abundance, diversity, species richness, and functional feeding guilds from fish catches in 2014 and 2019. Fish abundance declined 62% and species richness declined between 2014 and 2019. Smaller‐bodied, lower‐trophic level fishes dominated the catch. Our limited findings add insight into the status of a globally important fishery and highlight the need for more local collaborative fishery assessments. [ABSTRACT FROM AUTHOR]

Aims: To assess the excess risk of cardiovascular disease (CVD) associated with different criteria for metabolic health, and the interplay of body size, insulin sensitivity and metabolic health with CVD risk. Materials and Methods: We conducted a prospective study involving 115 638 participants from the China Cardiometabolic Disease and Cancer Cohort (4C) Study. Metabolic health was defined using three different definitions: (1) insulin sensitivity defined by homeostatic model assessment of insulin resistance index; (2) absence of metabolic syndrome according to the National Cholesterol Education Program Adult Treatment Panel III criteria; and (3) simultaneous absence of metabolic abnormalities (diabetes, hypertension, dyslipidaemia). The primary endpoint was a composite of incident CVD events comprising the first occurrence of myocardial infarction, stroke, heart failure, or cardiovascular death. Results: During a mean 3.61‐year follow‐up period, obese individuals with insulin sensitivity (multivariable‐adjusted hazard ratio [HR] 1.69, 95% confidence interval [CI] 1.37–2.08), or without metabolic syndrome (HR 1.46, 95% CI 1.13–1.89) still exhibited increased CVD risks, when compared to their normal‐weight counterparts. Otherwise, those with obesity but simultaneous absence of metabolic abnormalities demonstrated similar CVD risk compared to normal‐weight individuals (HR 0.91, 95% CI 0.53–1.59). CVD risk increased with the number of abnormalities across body mass index categories, regardless of insulin sensitivity. Conclusions: This study emphasizes the need for refined definitions of metabolic health and advocates for meticulous screening for metabolic abnormalities to reduce cardiovascular risks, even in individuals with normal weight and insulin sensitivity. [ABSTRACT FROM AUTHOR]

Cyclic rodent populations exhibit pronounced changes in body mass associated with the population cycle phase, long-known as Chitty effect. Although Chitty effect is a common epiphenomenon in both America and Europe, there is still incomplete evidence about the generality of these patterns across the entire range of most species. Moreover, despite decades of research, the underlying factors driving Chitty effect remains poorly understood. Here, we examined the influence of intrinsic and extrinsic factors that may underlie observed patterns in vole size variation in the Iberian common vole Microtus arvalis asturianus. We weighed and measured 2816 adult voles that were captured during 6 trapping periods. Vole numbers and body mass showed strong period- and phase-related variation both in females and males, demonstrating marked Chitty effect in the studied population. Body mass of adult males correlated with body length, evidencing that heavier males are also structurally larger. Statistical models showed that probability of occurrence of large-sized vole (> 37 g) was significantly more likely in reproductive males, during increase and peak phases, and it was modulated by habitat, with crop fields and field margins between crops showing an increased likelihood. We suggest an effect of the habitat on vole body mass mediated by predation. [ABSTRACT FROM AUTHOR]

Conservation successes in Europe have sparked the recovery of apex predators, which may affect the populations of mesopredators. The mesopredator release hypothesis (MRH) predicts that a decline in apex predators triggers a ‘release’ of mesopredators from suppression. We expanded the MRH to include predictions of inverse responses following increases in apex predator abundance or distribution. We examined European mesopredator responses to changes in apex predator populations and evaluated the extended MRH's explanatory power. We examined the results of 47 studies on European predators for supporting evidence, mixed evidence, no evidence, or contrasting evidence for the extended MRH. Out of 38 apex predator – mesopredator pairings, 10 predominantly supported the extended MRH, while others provided limited or no support. In 23 instances across 17 pairings, mesopredator responses contradicted predictions. Initial findings suggest the extended MRH better predicts mesopredator responses in pairings with intermediate to large body size differences and in pairings where mesopredators primarily hunt. Our results reveal non‐uniform mesopredator responses to changing apex predator populations. This emphasises the complexity of predator interactions, which extends beyond suppression. We suggest the MRH's scope is more restricted than previously thought, cautioning against overreliance on the MRH as a default expectation for European mesopredator responses to apex predator population changes. [ABSTRACT FROM AUTHOR]

Background: The animal sperm shows high diversity in morphology, components, and motility. In the lepidopteran model insect, the silkworm Bombyx mori, two types of sperm, including nucleate fertile eupyrene sperm and anucleate unfertile apyrene sperm, are generated. Apyrene sperm assists fertilization by facilitating the migration of eupyrene spermatozoa from the bursa copulatrix to the spermatheca. During spermatogenesis, eupyrene sperm bundles extrude the cytoplasm by peristaltic squeezing, while the nuclei of the apyrene sperm bundles are discarded with the same process, forming matured sperm. Results: In this study, we describe that a mechanoreceptor BmPiezo, the sole Piezo ortholog in B. mori, plays key roles in larval feeding behavior and, more importantly, is essential for eupyrene spermatogenesis and male fertility. CRISPR/Cas9-mediated loss of BmPiezo function decreases larval appetite and subsequent body size and weight. Immunofluorescence analyses reveal that BmPiezo is intensely localized in the inflatable point of eupyrene sperm bundle induced by peristaltic squeezing. BmPiezo is also enriched in the middle region of apyrene sperm bundle before peristaltic squeezing. Cytological analyses of dimorphic sperm reveal developmental arrest of eupyrene sperm bundles in BmPiezo mutants, while the apyrene spermatogenesis is not affected. RNA-seq analysis and q-RT-PCR analyses demonstrate that eupyrene spermatogenic arrest is associated with the dysregulation of the actin cytoskeleton. Moreover, we show that the deformed eupyrene sperm bundles fail to migrate from the testes, resulting in male infertility due to the absence of eupyrene sperm in the bursa copulatrix and spermatheca. Conclusions: In conclusion, our studies thus uncover a new role for Piezo in regulating spermatogenesis and male fertility in insects. [ABSTRACT FROM AUTHOR]

Background: Myxomatous mitral valve disease (MMVD) is the most common acquired cardiovascular disease in small breed dogs. In contrast to human patients with heart failure (HF), iron deficiency (ID) prevalence in dogs with MMVD is weakly known. The study aimed to assess the usability of ID markers in serum and reticulocyte parameters from whole blood of dogs with MMVD to evaluate early ID symptoms. Results: Sixty-eight dogs (43 male and 25 female) were included in the study. MMVD dogs were assigned according to the 2019 ACVIM guidelines for groups B1 (n = 9), B2 (n = 10), C (n = 27) and D (n = 10). Groups were also combined into B1 and B2 as non-symptomatic HF and C with D as symptomatic HF. Healthy controls were 12 dogs. Serum iron concentration below the reference range in dogs with MMVD was 12.5%. Other ID indices, such as %SAT, UIBC, and TIBC were similar in the MMVD groups and healthy controls (p > 0.05 for all parameters). Statistical comparison between control group and 4 groups of different stages of MMVD showed that significant differences occur only in serum transferrin. The assessment of ferritin and soluble transferrin receptors using Western Blotting did not show differences between control (n = 7) and MMVD (n = 33) dogs. Study has shown positive correlation between ID parameters and echocardiographic indices such as LA/Ao and LVIDdN, and some biochemical parameters. A significant increase in reticulocytes percentage, assessed manually, was observed in the HF group of animals (p = 0.027) compared to the control group. Conclusions: Studies have shown that ID parameters in serum are not significantly different in dogs with MMVD compared to healthy dogs. However, there is a clear correlation between atrial size and normalised left ventricular size to body size and some biochemical parameters, including ID parameters and therefore the severity of MMVD. [ABSTRACT FROM AUTHOR]

Nematodes disperse passively and are amongst the smallest invertebrates on Earth. Free-living nematodes in mountain lakes are highly tolerant of environmental variations and are thus excellent model organisms in dispersal studies, since species-environment relationships are unlikely to interfere. In this study, we investigated how population or organism traits influence the stochastic physical nature of passive dispersal in a topologically complex environment. Specifically, we analyzed the influence of female proportion and body size on the geographical distribution of nematode species in the mountain lakes of the Pyrenees. We hypothesized that dispersal is facilitated by (i) a smaller body size, which would increase the rate of wind transport, and (ii) a higher female proportion within a population, which could increase colonization success because many nematode species are capable of parthenogenetic reproduction. The results showed that nematode species with a low proportion of females tend to have clustered spatial distributions that are not associated with patchy environmental conditions, suggesting greater barriers to dispersal. When all species were pooled, the overall proportion of females tended to increase at the highest elevations, where dispersal between lakes is arguably more difficult. The influence of body size was barely relevant for nematode distributions. Our study highlights the relevance of female proportion as a mechanism that enhances the dispersal success of parthenogenetic species, and that female sex is a determining factor in metacommunity connectivity. [ABSTRACT FROM AUTHOR]

Successful regeneration of missing tissues requires seamless integration of positional information along the body axes. Planarians, which regenerate from almost any injury, use conserved, developmentally important signaling pathways to pattern the body axes. However, the molecular mechanisms which facilitate cross talk between these signaling pathways to integrate positional information remain poorly understood. Here, we report ap21-activatedkinase (smed-pakl) which functionally integrates the anterior--posterior (AP) and the medio-lateral (ML) axes.pakl inhibits WNT/β-catenin signaling along the AP axis and, functions synergistically with the β-catenin-independent WNT signaling of the ML axis. Furthermore, this functional integration is dependent on warts and merlin--the components of the Hippo/Yorkie (YKI) pathway. Hippo/YKI pathway is a critical regulator of body size in flies and mice, but our data suggest the pathway regulates body axes patterning in planarians. Our study provides a signaling network integrating positional information which can mediate coordinated growth and patterning during planarian regeneration. [ABSTRACT FROM AUTHOR]

In holometabolous insects, such as Drosophila and Bombyx, prothoracicotropic hormone (PTTH) is well established to be critical in controlling developmental transitions and metamorphosis by stimulating the biosynthesis of ecdysone in the prothoracic glands (PGs). However, the physiological role of PTTH and the receptor Torso in hemimetabolous insects remains largely unexplored. In this study, homozygous PTTH- and Torso-null mutants of the brown planthopper (BPH), Nilaparvata lugens, were successfully generated by employing clustered regularly interspaced short palindromic repeats/CRISPR-associated 9 (CRISPR–Cas9). Further characterization showed that both NlPTTH−/− and NlTorso−/− mutants exhibited prolonged nymphal duration and increased final adult size. Enzyme-linked immunosorbent assay (ELISA) revealed that NlPTTH−/− and NlTorso−/− mutants exhibited a significant reduction in 20-hydroxyecdysone (20E) in fifth-instar nymphs at 48 h post-ecdysis compared to Wt controls. Furthermore, our results indicated that both NlPTTH−/− and NlTorso−/− mutants had shortened lifespan, reduced female fecundity, and reduced egg hatching rates in adults. These findings suggest a conserved role for the PTTH–Torso signaling system in the regulation of developmental transitions by stimulating ecdysone biosynthesis in hemimetabolous insects. [ABSTRACT FROM AUTHOR]

Mawsonia constitutes one of the most conspicuous fossil coelacanth taxa, due to its unique anatomy and possible maximum body size. It typifies Mesozoic coelacanth morphology, before the putative disappearance of the group in the fossil record. In this work, the three‐dimensional cranial anatomy and body size estimations of this genus are re‐evaluated from a recently described specimen from Upper Jurassic deposits of Uruguay. The 3D restoration was performed directly on the material based on anatomical information provided by the living coelacanth Latimeria and previous two‐dimensional restorations of the head of Mawsonia. The montage was then scanned with computed tomography and virtually adjusted to generate an interactive online resource for future anatomical, taxonomic and biomechanical research. In general terms, the model constitutes a tool to improve both the anatomical knowledge of this genus and its comparison with other coelacanths. It also facilitates the evaluation of possible evolutionary trends and the discussion of particular features with potential palaeobiological implications, such as the anterior position of the eye and the development of the pseudomaxillary fold. Regarding the body size, a previous model for body size estimation based on the gular plate was submitted to OLS, RMA, segmented linear and PGLS regressions (including the evaluation of regression statistics, variance analysis, t‐tests and residual analysis). The results point to a power relationship between gular and total lengths showing a better support than a simple linear relationship. The new resulting equations were applied to the studied individual and are provided for future estimates. Although an isometric evolutionary growth cannot be rejected with the available evidence, additional models developed with other bones will be necessary to evaluate possible hidden evolutionary allometric trends in this group of fishes, thus avoiding overestimates. [ABSTRACT FROM AUTHOR]

Simple Summary: Lines of White Leghorn chickens divergently selected for high or low antibody response to sheep red blood cells (SRBC) have undergone selection for 50 generations. These lines have allowed for insights into understanding the phenotypic and genotypic changes occurring under phenotypic selection for this single trait. When collecting organ samples from 18-day embryos of generation 48, a difference was seen in the size of the spleen. This observation led to the question of whether the growth of organs associated with immunity had changed after almost 50 generations of selection. Body weights and weights of immune organs representing both primary and secondary immune systems were taken at nine time points. The results showed that divergent selection for the response to SRBC and relaxation of selection resulted in differences in spleen and bursa weights during the later stages of embryonic development and early post-hatch. Long-term divergent selection from a common founder population for a single trait—antibody response to sheep erythrocytes 5 days post-injection—has resulted in two distinct lines of White Leghorn chickens with a well-documented difference in antibody titers: high (HAS)- and low (LAS)-antibody selected lines. Subpopulations—high (HAR)- and low (LAR)-antibody relaxed—were developed from generation 24 of the selected lines to relax selection. The objective of the current experiment was to determine if this long-term selection and relaxation of selection impacted the growth of two organs important to chicken immunity: the spleen and the bursa of Fabricius. Spleens and bursae were obtained from ten chickens per line at nine timepoints (E18, D0, D6, D13, D20, D35, D49, D63, and D91) throughout their rapid growth phase and presented as a percent of body weight. Significance was set at p ≤ 0.05. For the spleen, all lines consistently increased in size relative to body weight to D49, followed by a consistent decline. All lines had a similar growth pattern, but HAS spleens grew faster than LAS spleens. For the bursa, LAS was smaller than the other three lines as an embryo and also smaller than HAS through D63. In the selected lines, bursa weight peaked at D35, whereas the relaxed lines peaked at D49. By D91, there was no difference between lines. Artificial and natural selection, represented by the long-term selected and relaxed antibody lines, resulted in differences in the growth patterns and relative weights of the spleen and bursa of Fabricius. [ABSTRACT FROM AUTHOR]

Simple Summary: Body size is undoubtedly one of the most critical characteristics that serves as a reliable predictor of an organism's physiological rates and life-history traits. Notably, we observe a decrease in metabolic rate per unit mass with increasing body size. Given that molecular alterations in mitochondrial genes respond to changes in energy demands, significant variations in metabolic rates across different body sizes may exert an influence on mitochondrial evolution. The terrestrial Cetartiodactyla provides an exceptional model for investigating this issue, owing to its remarkable range of body sizes that spans from less than 2 kg to over 1200 kg. Our findings suggest that mitochondrial DNA protein-coding genes in small-bodied species have undergone a more intense purifying selection. In summary, our research contributes to a deeper understanding of the molecular evolutionary patterns of mitochondria, highlighting the interplay between genomic evolution and phenotypic traits. Body size may drive the molecular evolution of mitochondrial genes in response to changes in energy requirements across species of different sizes. In this study, we perform selection pressure analysis and phylogenetic independent contrasts (PIC) to investigate the association between molecular evolution of mitochondrial genome protein-coding genes (mtDNA PCGs) and body size in terrestrial Cetartiodactyla. Employing selection pressure analysis, we observe that the average non-synonymous/synonymous substitution rate ratio (ω) of mtDNA PCGs is significantly reduced in small-bodied species relative to their medium and large counterparts. PIC analysis further confirms that ω values are positively correlated with body size (R2 = 0.162, p = 0.0016). Our results suggest that mtDNA PCGs of small-bodied species experience much stronger purifying selection as they need to maintain a heightened metabolic rate. On the other hand, larger-bodied species may face less stringent selective pressures on their mtDNA PCGs, potentially due to reduced relative energy expenditure per unit mass. Furthermore, we identify several genes that undergo positive selection, possibly linked to species adaptation to specific environments. Therefore, despite purifying selection being the predominant force in the evolution of mtDNA PCGs, positive selection can also occur during the process of adaptive evolution. [ABSTRACT FROM AUTHOR]

Aim Location Taxon Methods Results Main Conclusions Climatic gradients shape geographic variation in phenotypic traits that are involved in animal thermoregulation. Therefore, increasing temperatures under global warming are expected to cause change over time in traits that show predictable spatial patterns according to environmental clines (body and appendage size, tegument coloration), as well exemplified by biogeographic rules and shown by increasing literature at a local scale. However, whether temporal shifts in phenotypic traits vary spatially according to the magnitude of the change in local climatic conditions is still unknown.World.Barn owl species complex (Tyto alba group).By using thousands of museum specimens collected across the globe from 1901 to 2018, we calculated within‐population change over time in wing length, bill length and melanin‐based plumage coloration and examined whether these trends differed across geographic regions, latitudes and gradients of climate changes.We showed that populations exposed to an increasing warmer climate were subjected to a more marked decrease in body size, as gauged by wing length, and also absolute bill length that displayed a similar, although less steep, pattern of shrinking over time. In addition, phaeomelanin‐based ventral plumage colour has become paler in regions where the climate changed into warmer and drier, and darker where both temperature and precipitation increased.These trends are generally coherent with the predictions based on Bergmann's and Gloger's rules, but not Allen's rule, and suggest that temporal shifts in body size and tegument colour depend on the magnitude of the alteration in climatic conditions, with populations living in regions where the climate has changed the most that are subjected to more marked phenotypic changes. Spatio‐temporal variation in climate has driven within‐species phenotypic clines, and it is expected to increase differences among populations according to the predicted further climate change. [ABSTRACT FROM AUTHOR]

Heterospecific sociability could enhance invasion success in social species since social non‐natives usually belong to small founding populations during the early stages of invasion. The twospot livebearer (Pseudoxiphophorus bimaculatus) is native to Central America and southern Mexico and is recently recognised as invasive in the Mexican Central Plateau, where it poses a threat to native species. Here, we evaluated twospot livebearer sociability towards either a conspecific pair or a shoal of four fish with one of four possible compositions, all conspecifics or two conspecifics combined with either two guppies, two porthole livebearers or two twoline skiffias. In a second experiment, foraging time, latency to feed, first fish to begin foraging and aggressive interactions were recorded under the same social conditions used in the sociability experiment, with body size included as a covariate in both experiments. All focal twospot livebearers spent significantly more time with the given shoals rather than with the available space in the aquarium. They showed a higher tendency to associate with small shoals of conspecifics than with pairs. Larger twospot livebearers associated more, regardless of the social condition. Twospot livebearer fed more with porthole livebearers, less with guppies and similarly with twoline skiffias. Latency to forage did not vary significantly between social conditions. Twospot livebearers were involved in more aggressive interactions when with guppies or porthole livebearers than when with native twoline skiffias or conspecifics. Twospot livebearers could gain benefits from associating with natives and conspecifics, but not with other invasive poeciliids. Heterospecific shoaling behaviour with natives may enhance invasion success during early stages when conspecifics are scarce while associating with other invasive poeciliids could lead to increased competition. Further research is needed on heterospecific interactions of non‐natives to better understand their behavioural role in invasion likelihood. [ABSTRACT FROM AUTHOR]

Genome duplications and ploidy transitions have occurred in nearly every major taxon of eukaryotes, but they are far more common in plants than in animals. Due to the conservation of the nuclear:cytoplasmic volume ratio increased DNA content results in larger cells. In plants, polyploid organisms are larger than diploids as cell number remains relatively constant. Conversely, vertebrate body size does not correlate with cell size and ploidy as vertebrates compensate for increased cell size to maintain tissue architecture and body size. This has historically been explained by a simple reduction in cell number that matches the increase in cell size maintaining body size as ploidy increases, but here we show that the compensatory mechanisms that maintain body size in triploid zebrafish are tissue-specific: A) erythrocytes respond in the classical pattern with a reduced number of larger erythrocytes in circulation, B) muscle, a tissue comprised of polynucleated muscle fibers, compensates by reducing the number of larger nuclei such that myofiber and myotome size in unaffected by ploidy, and C) vascular tissue compensates by thickening blood vessel walls, possibly at the expense of luminal diameter. Understanding the physiological implications of ploidy on tissue function requires a detailed description of the specific mechanisms of morphological compensation occurring in each tissue to understand how ploidy changes affect development and physiology. [Display omitted] • Tissue-specific mechanisms compensate for changes in cell size. • Blastomere size, cleavage pattern and rate are not affected by ploidy. • Erythrocytes conform to the canonical pattern of 'fewer but larger cells'. • Multinucleate skeletal muscle cells adjust the number of nuclei to maintain size. • Vasculature is comprised of the same number and pattern of larger endothelial cells. [ABSTRACT FROM AUTHOR]

Mg2+ is a vital ion involved in diverse cellular functions by forming complexes with ATP. Intracellular Mg2+ levels are tightly regulated by the coordinated actions of multiple Mg2+ transporters, such as the Mg2+ efflux transporter, cyclin M (CNNM). Caenorhabditis elegans (C. elegans) worms with mutations in both cnnm-1 and cnnm-3 exhibit excessive Mg2+ accumulation in intestinal cells, leading to various phenotypic abnormalities. In this study, we investigated the mechanism underlying the reduction in body size in cnnm-1; cnnm-3 mutant worms. RNA interference (RNAi) of gtl-1 , which encodes a Mg2+-intake channel in intestinal cells, restored the worm body size, confirming that this phenotype is due to excessive Mg2+ accumulation. Moreover, RNAi experiments targeting body size-related genes and analyses of mutant worms revealed that the suppression of the target of rapamycin complex 2 (TORC2) signaling pathway was involved in body size reduction, resulting in downregulated DAF-7 expression in head ASI neurons. As the DAF-7 signaling pathway suppresses dauer formation under stress, cnnm-1; cnnm-3 mutant worms exhibited a greater tendency to form dauer upon induction. Collectively, our results revealed that excessive accumulation of Mg2+ repressed the TORC2 signaling pathway in C. elegans worms and suggest the novel role of the DAF-7 signaling pathway in the regulation of their body size. [Display omitted] • Mg2+ accumulation in the intestine causes body size reduction in C. elegans. • Suppression of TORC2 mediates body size reduction in cnnm-1; cnnm-3 mutants. • Intestinal TORC2 signaling affects neuronal DAF-7 signaling. • Neuronal DAF-7 signaling is involved in body size regulation. [ABSTRACT FROM AUTHOR]

The thermal tolerance of ectotherms is a critical factor that influences their distribution, physiology, behaviour, and, ultimately, survival. Understanding the factors that shape thermal tolerance in these organisms is, therefore, of great importance for predicting their responses to forecasted climate warming. Here, we investigated the voluntary thermal maximum (VTmax) of nine grassland viper taxa and explored the factors that influence this trait. The small size of these vipers and the open landscape they inhabit render them particularly vulnerable to overheating and dehydration. We found that the VTmax of grassland vipers is influenced by environmental temperature, precipitation, short-wave flux, and individual body size, rather than by phylogenetic relatedness. Vipers living in colder environments exhibited a higher VTmax, contradicting the hypothesis that environmental temperature is positively related to VTmax. Our findings emphasize the importance of considering local to regional adaptations and environmental conditions when studying thermal physiology and the evolution of thermal tolerance in ectotherms. [ABSTRACT FROM AUTHOR]

Secondary forests are increasingly important for biodiversity conservation and ecosystem functioning. Yet, we know little on how species interactions shift across the wide range of life history strategies in the context of forest succession, especially for non‐trophic animal social systems.Using data from mixed‐species flocks (hereafter MSFs) and life history and morphological traits from the 'fast‐slow' continuum, we utilized a novel combination of network theory and trait‐based ecology to examine the assembly of associations of MSFs among species with different fast‐slow strategies across stages of forest succession that exhibit different degrees of forest complexity.MSFs formed the most connected and cohesive network in the intermediate successional stage. In contrast, we observed the least connected and cohesive network in the early stage, and a strongly connected but intermediately cohesive network in the late stage. Fast species with smaller body size and mass, and larger clutch size, were gradually replaced by slow species during succession. Interspecific associations generally shifted from those among similarly fast species (early stage) to associations between fast and slow species (intermediate stage), and finally to those among similarly slow species (late stage).We suggest that vegetation complexity (e.g. tree size, height, diversity and canopy cover), related to the availability of resources and number of niches, shaped the network structure and functional composition of MSFs. Although the late successional forests play an irreplaceable role in protecting forest specialists (i.e. slow species), intermediate stage forests should be also protected, because the large‐sized networks formed by MSFs at intermediate stages can simultaneously conserve more species with varying ecological strategies. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Body size variation is central in the evolution of life‐history traits in amphibians, but the underlying genetic architecture of this complex trait is still largely unknown. Herein, we studied the genetic basis of body size and fecundity of the alternative morphotypes in a wild population of the Greek smooth newt (Lissotriton graecus). By combining a genome‐wide association approach with linkage disequilibrium network analysis, we were able to identify clusters of highly correlated loci thus maximizing sequence data for downstream analysis. The putatively associated variants explained 12.8% to 44.5% of the total phenotypic variation in body size and were mapped to genes with functional roles in the regulation of gene expression and cell cycle processes. Our study is the first to provide insights into the genetic basis of complex traits in newts and provides a useful tool to identify loci potentially involved in fitness‐related traits in small data sets from natural populations in non‐model species. [ABSTRACT FROM AUTHOR]

Variability in phenological shifts (seasonal changes in biological events) has become more common with climate change. As phenological variability increases due to climatic factors, species interactions within diverse communities can be affected. Shifts in hatching phenology can lead to body size variability that can alter species interactions, especially within and across trophic levels in complex food webs. To understand the effects of hatching phenology and food web complexity on prey communities, we conducted an experiment with ectotherms from ponds by manipulating hatching synchrony of a prey species across three dates and food web complexity. We hypothesized that predation on prey would be highest in the lowest synchrony treatment due to predator satiation effects in high synchrony additions. Food webs with top predators present had the lowest survival rates for prey compared to other food webs. Prey size at metamorphosis was also highest in the top predator food webs, suggesting a thinning effect. Hatching synchrony treatments did not have a significant impact on prey survival or size at metamorphosis except in treatments where intermediate and top predators were absent. Overall, our results show that top-down effects of predators may be enough to suppress the influence of phenological shifts in prey. [ABSTRACT FROM AUTHOR]

Amniotes differ substantially in absolute and relative brain size after controlling for allometry, and numerous hypotheses have been proposed to explain brain size evolution. Brain size is thought to correlate with processing capacity and the brain's ability to support complex manipulation such as nest‐building skills. The increased complexity of nest structure is supposed to be a measure of an ability to manipulate nesting material into the required shape. The degree of nest‐structure complexity is also supposed to be associated with body mass, partly because small species lose heat faster and delicate and insulated nests are more crucial for temperature control of eggs during incubation by small birds. Here, we conducted comparative analyses to test these hypotheses by investigating whether the complexity of species‐typical nest structure can be explained by brain size and body mass (a covariate also to control for allometric effects on brain size) across 1353 bird species from 147 families. Consistent with these hypotheses, our results revealed that avian brain size increases as the complexity of the nest structure increases after controlling for a significant effect of body size, and also that a negative relationship exists between nest complexity and body mass. [ABSTRACT FROM AUTHOR]

In animal fights, there are often size asymmetries between opponents. Although larger individuals typically dominate smaller ones, size is not the sole determining factor, as the competitors' motivation, aggressiveness, resource value, physiological characteristics, and strength also play crucial roles in fighting outcomes. In this study, we evaluated the influence of body size on dominance hierarchy and contest success during intra‐ and inter‐specific contests in two fish species: the native mojarra of the Balsas basin Amphilophus istlanus and the invasive convict cichlid Amatitlania nigrofasciata. We used size‐asymmetric males to carry out experimental contests. The number and type of aggressive behaviors, time to contest outcome, and dominant individual at the end of the contest were determined. In contests between two native mojarra, the smaller individual always lost. In contests between convict cichlids, the smaller contestants lost in all contests where size asymmetry was greater than 20%. In interspecific contests, the native mojarra performed more aggressive behaviors than the invasive convict cichlid and dominated convict cichlids despite a size disadvantage. This suggests that in terms of competition via interference, the native mojarra can counter the arrival of the invasive convict cichlid. [ABSTRACT FROM AUTHOR]

Full‐body avatar presence is important for immersive social and environmental interactions in digital reality. However, current devices only provide three six degrees of freedom (DOF) poses from the headset and two controllers (i.e. three‐point trackers). Because it is a highly under‐constrained problem, inferring full‐body pose from these inputs is challenging, especially when supporting the full range of body proportions and use cases represented by the general population. In this paper, we propose a deep learning framework, DivaTrack, which outperforms existing methods when applied to diverse body sizes and activities. We augment the sparse three‐point inputs with linear accelerations from Inertial Measurement Units (IMU) to improve foot contact prediction. We then condition the otherwise ambiguous lower‐body pose with the predictions of foot contact and upper‐body pose in a two‐stage model. We further stabilize the inferred full‐body pose in a wide range of configurations by learning to blend predictions that are computed in two reference frames, each of which is designed for different types of motions. We demonstrate the effectiveness of our design on a large dataset that captures 22 subjects performing challenging locomotion for three‐point tracking, including lunges, hula‐hooping, and sitting. As shown in a live demo using the Meta VR headset and Xsens IMUs, our method runs in real‐time while accurately tracking a user's motion when they perform a diverse set of movements. [ABSTRACT FROM AUTHOR]

Objectives: This study developed multivariate law enforcement officer (LEO) body models for digital simulation of LEO accommodation in police cruiser cabs. Background: Anthropometrically accurate digital LEO body models, representing the United States LEOs, for computerized LEO cruiser interface simulations are lacking. Methods: Twenty body dimensions (with and without gear combined) of 756 male and 218 female LEOs were collected through a stratified national survey using a data collection trailer that traveled across the US. A multivariate Principal Component Analysis (PCA) approach was used to develop digital LEO body models. Results: Fifteen men and 15 women representing unique body size and shape composition of the LEO population were identified. A combined set of 24 male and female models (removal of 6 redundant models for which female and male models overlapped) is suggested. Conclusions: A set of 24 digital LEO body models in 3-dimensional form, along with their anthropometric measurements, were developed to facilitate LEO cruiser cab design. Application: Digital modeling software developers can use the models and their anthropometric data to build digital avatars for simulated evaluation of LEO cruiser cab configuration, console communication-equipment fitting, and cruiser ingress/egress access arrangement. LEO vehicle and equipment designers also can use eight key body dimensions (i.e., stature, buttock-popliteal length, eye height sitting, knee height sitting, shoulder-grip length, popliteal height, sitting height, and body weight) of the body models to recruit 24 human subjects to physically evaluate their vehicle prototypes for improved vehicle and equipment design. [ABSTRACT FROM AUTHOR]

Quantifying genetic structure and levels of genetic variation are fundamentally important to predicting the ability of populations to persist in human‐altered landscapes and adapt to future environmental changes. Genetic structure reflects the dispersal of individuals over generations, which can be mediated by species‐level traits or environmental factors. Dispersal distances are commonly positively associated with body size and negatively associated with the amount of degraded habitat between sites, motivating the investigation of these potential drivers of dispersal concomitantly. We quantified genetic structure and genetic variability within populations of seven bee species from the genus Euglossa across fragmented landscapes. We genotyped bees at SNP loci and tested the following predictions: (1) deforested areas restrict gene flow; (2) larger species have lower genetic structure; (3) species with greater resource specialization have higher genetic structure; and (4) sites surrounded by more intact habitat have higher genetic diversity. Contrasting with previous work on bees, we found no associations between body size and genetic structure. Genetic structure was higher for species with greater resource specialization, and the amount of intact habitat between or surrounding sites was positively associated with parameters reflecting gene flow and genetic diversity. These results challenge the dominant paradigm that individuals of larger species disperse farther, and they suggest that landscape and resource requirements are important factors mediating dispersal. [ABSTRACT FROM AUTHOR]

Elucidating the underlying mechanisms behind variations of animal space and resource use is crucial to pinpoint relevant ecological phenomena. Organism's traits related to its energy requirements might be central in explaining behavioral variation, as the ultimate goal of a forager is to fulfill its energy requirements. However, it has remained poorly understood how energy requirements and behavioral patterns are functionally connected. Here we aimed to assess how body mass and standard metabolic rate (SMR) influence behavioral patterns in terms of cumulative space use and time spent in an experimental patchy environment, both within species and among individuals irrespective of species identity. We measured the behavioral patterns and SMR of two invertebrate species, that is, amphipod Gammarus insensibilis, and isopod Lekanesphaera monodi, individually across a range of body masses. We found that species of G. insensibilis have higher SMR level, in addition to cumulatively exploring a larger space than L. monodi. Cumulative space use scaled allometrically with body mass, and it scaled isometrically with SMR in both species. While time spent similarly in both species was characterized by negative body mass and SMR dependence, it was observed that L. monodi individuals tended to stay longer in resource patches compared to G. insensibilis individuals. Our results further showed that within species, body mass and metabolic rate explained a similar amount of variation in behavior modes. However, among individuals, regardless of species identity, SMR had stronger predictive power for behavioral modes compared to body mass. This suggests that SMR might offer a more generalized and holistic description of behavioral patterns that extend beyond species identity. Our study on the metabolic and body mass scaling of space and resource use behavior sheds light on higher‐order ecological processes such as species' competitive coexistence along the spatial and trophic dimensions. [ABSTRACT FROM AUTHOR]

Aim: The abundant niche‐centre hypothesis has been used to describe patterns of species abundance relative to position in ecological niche space. Such relationships, however, are inconsistently recovered and may be obscured due to non‐equilibrium distributions, such as those caused novel interactions with exotic species. Here, we explore patterns of fitness for the nine‐spotted lady (Coccinella novemnotata) following the introduction of an exotic competitor, the seven‐spotted lady beetle (C. septempunctata). We examine how niche overlap between species may be causing a range reduction for C. novemnotata through a modified abundant niche‐centre relationship. Location: North America. Methods: We applied a time‐oriented view of the abundant niche‐centre relationship for C. novemnotata, both before and after the introduction of C. septempunctata. We tested for both niche overlap and correlation between C. novemnotata body size (i.e. fitness) and the distance from its niche centroid relative to the invasion status of C. septempunctata. Results: The current niche space currently occupied by C. novemnotata is equivalent to its historic niche but has shifted to avoid overlap with C. septempunctata. A historic abundant niche‐centre relationship with larger individuals closer to the niche centroid was observed for C. novemnotata. However, this pattern changed to have smaller beetles near the niche centroid when the current distribution was considered. Main Conclusions: Fitness patterns displayed by C. novemnotata are effectively described by the abundant niche‐centre hypothesis. However, this relationship was modified with the introduction of C. septempunctata. Coccinella novemnotata is not excluded from previously suitable areas that correspond to niche space nearest to its niche centroid. Abundant niche‐centre relationships may provide strong predictions of species' fitness across a species geographic range; however, these relationships may be obscured by novel pressures resulting in non‐equilibrium states. [ABSTRACT FROM AUTHOR]

This paper examines the various labels ascribed to males in the heterosexual discourse among female undergraduates in Nigeria. Insights from Community of Practice and Sexual Script Theory were used to demonstrate the use of situated linguistic choices to establish the differentials in male sexual behaviours. Data for the study were generated through participant observation and unstructured interviews with the aid of audiotape recordings and field notes. The study involves a representative sample of 22 female undergraduates who served as participants and research assistants. The findings reveal that situated language practices stimulate heterosexual discourses where female undergraduates creatively ascribe labels to the different males' sexual scripts. The labels include those related to male sexual performance, body size and size of sex organs, financial and marital status, familial and gatekeeping roles, and other routine sexual behaviours shown by men in sexual phases such as advances, arousal and intercourse. The scripts are also combined to re-enact the peculiar sexual narratives by the female students that show emerging sexual orientations. It is believed that the categorisation of such males' sexual behaviours in the University social contexts, would provide a basis for comparison with the sexual practices of other young adults' social groups across the globe. The paper discusses the various strands of sexual scripts shown by men in their heterosexual relationships with female undergraduates in a Nigerian University. The students ascribed labels based on the sexual performance, economic and marital status, and other routine behaviours that have an impact on the male sexual lifestyle. [ABSTRACT FROM AUTHOR]

Sexual conflict is believed to be an important evolutionary force driving phenotypic diversification, especially sexual dimorphism. Males of diving beetles sometimes resort to coercive tactics to increase their chances of successful reproduction, which can impose costs on females. Sexual conflict can also drive sexual size dimorphism (SSD), particularly in species where males are larger than females. In this context, Rensch's rule states that SSD tends to increase with body size in species with male-biased SSD and decrease with body size in species with female-biased SSD. The role of sexual conflict in driving the evolution of the allometric relationships between males and females remains unclear. We addressed whether sexual conflict in diving beetles might drive SSD. We found that dytiscids do not follow Rensch's rule, whereby the SSD is isometric in relationship to species body size. Species with adhesive pads (Dytiscinae) showed a more pronounced SSD than other diving beetle species. These results suggest that the presence of adhesive pads might reduce the force necessary to control female movement during copulation and drive the evolution of smaller males. The findings of this study provide new insights into the role of sexual conflict in driving the evolution of SSD in animals. [ABSTRACT FROM AUTHOR]

The common shrew (Sorex araneus) is one of the most studied shrew species of the Western Palaearctic. Despite this, the general drivers underlying morphological variation still remain unclear. Here we provide evidence for contradictory effects of climatic and geographical factors on the mandible of the common shrew. At the continental scale there is a negative correlation between body- and skull-size and latitude and longitude but at regional scales such an association is often not apparent; in fact, in some cases body size and skull size follow the opposite trend and observations at various scales yielded contradictory results. We studied shrew mandibles using geometric morphometrics and tested for correlations of their size and shape with selected geographical and climatic variables. We examined 1155 mandibles from 29 European localities and found significant interpopulation differences in both size and shape. Centroid size negatively correlated with latitude. We also found that centroid size was significantly correlated with altitude and annual precipitation. Our results confirmed an inverse Bergmann's rule relationship in S. araneus along the transect from the Baltic to the Adriatic Sea. Regarding mandible shape, Slovenian shrews were the most distant from all other studied populations. We discuss how altitude and precipitation can influence the morphology of the common shrew. [ABSTRACT FROM AUTHOR]

Tracking insect biodiversity trends and predicting future trajectories is limited by a lack of monitoring data across large spatiotemporal scales. DNA metabarcoding is a time‐ and cost‐efficient method to obtain these data, but has several potential limitations in comparison to traditional morphological approaches. For example, metabarcoding may miss low‐abundance or smaller bodied individuals and is limited to presence/absence information, which may bias estimates of biodiversity and community composition. However, few comparisons of metabarcoding and morphology‐based identification have been made using insects, the by far most diverse animal taxonomic group.Here, we compared terrestrial insect communities identified via morphology versus metabarcoding across four different habitats and three seasons (late spring, mid‐summer and early autumn) during 2019. We compared identified species and community richness, composition and body size, with a focus on key taxonomic groups of bees, true bugs, butterflies and hoverflies.We identified 252 total species, with 54.8% identified by both methods, whereas 21.4% and 19.8% were solely detected with metabarcoding or morphology, respectively. Overall, total community richness, taxonomic composition and community body size were similar between methods. Metabarcoding detection successes declined in low‐abundance and smaller taxa, particularly bees, hoverflies and true bugs; however, species richness of hoverflies and butterflies tended to be higher compared with morphological identification.Our results show that metabarcoding can provide an accurate overview of insect community differences that are comparable to those determined via morphological identification. We recommend that insect monitoring programmes consider incorporating metabarcoding, although future research is needed to overcome some remaining limitations. [ABSTRACT FROM AUTHOR]

Animal dispersal is often phenotype‐dependent and can exert evolutionary pressures on populations in which it occurs. The evolutionary pressure arising from phenotype‐dependent dispersal is called spatial sorting. We examined the evolutionary pressure arising from spatial sorting (sorting pressure) caused by downstream dispersal in juvenile white‐spotted char Salvelinus leucomaenis under ordinary flow conditions. We conducted outdoor experiments using an artificial channel with 10 steps to investigate the relationship between phenotypic characteristics and the occurrence or distance of downstream dispersal during five daytime hours. Six experiments were conducted using young‐of‐the‐year juveniles collected early in the morning of each experimental day. We focused on two phenotypes, fork length (body size) and station‐holding (SH) behavior, where juveniles remain sedentary on the substrate. Juveniles were assigned to the "SH group" if they exhibited SH behavior for more than 10 s during a 540‐s observation period, and to the "swimming group" if they exhibited SH behavior for less than 10 s. Juveniles in the swimming group had a higher occurrence of downstream dispersal than in the SH group. In addition, large juveniles in the SH group and small juveniles in the swimming group tended to show long dispersal distances. These results suggest an effective sorting pressure against juveniles with active swimming behavior. This sorting pressure may accumulate in isolated char populations located above a tall migration barrier and contribute to the creation and maintenance of the reported interpopulation variation in SH behavior. [ABSTRACT FROM AUTHOR]

Agonistic displays are one of the most diverse social behaviors that have important functions in animal's life history. However, their origin and driving factors have largely been unexplored. Here, we evaluated agonistic displays of 71 bat species across 10 families and classified these displays into two categories: (a) boxing displays where a bat attacks its opponent with its wrist and thumb and (b) pushing displays where a bat uses its head or body to hit a rival. We estimated the strength of the phylogenetic signal of the agonistic displays, revealed their origin, and tested the potential evolutionary relationships between agonistic behaviors and body size or resting posture (free hanging vs. contact hanging where the bat is in contact with some surface). We found that agonistic displays were phylogenetically conserved and that boxing displays are the ancestral state. Moreover, we found that bats with a free-hanging resting posture were more likely to exhibit boxing displays than pushing displays. In addition, bats with longer forearms do not have a higher propensity for boxing displays. This study expands our limited knowledge of the evolution of agonistic displays and highlights the importance of resting posture as a driving force in the diversity of agonistic displays. [ABSTRACT FROM AUTHOR]

Anthropogenic climate change is altering precipitation regimes at a global scale. While precipitation changes have been linked to changes in the abundance and diversity of soil and litter invertebrate fauna in forests, general trends have remained elusive due to mixed results from primary studies. We used a meta‐analysis based on 430 comparisons from 38 primary studies to address associated knowledge gaps, (i) quantifying impacts of precipitation change on forest soil and litter fauna abundance and diversity, (ii) exploring reasons for variation in impacts and (iii) examining biases affecting the realism and accuracy of experimental studies. Precipitation reductions led to a decrease of 39% in soil and litter fauna abundance, with a 35% increase in abundance under precipitation increases, while diversity impacts were smaller. A statistical model containing an interaction between body size and the magnitude of precipitation change showed that mesofauna (e.g. mites, collembola) responded most to changes in precipitation. Changes in taxonomic richness were related solely to the magnitude of precipitation change. Our results suggest that body size is related to the ability of a taxon to survive under drought conditions, or to benefit from high precipitation. We also found that most experiments manipulated precipitation in a way that aligns better with predicted extreme climatic events than with predicted average annual changes in precipitation and that the experimental plots used in experiments were likely too small to accurately capture changes for mobile taxa. The relationship between body size and response to precipitation found here has far‐reaching implications for our ability to predict future responses of soil biodiversity to climate change and will help to produce more realistic mechanistic soil models which aim to simulate the responses of soils to global change. [ABSTRACT FROM AUTHOR]

As described by the temperature–size rule paradigm, fish living in warmer temperatures grow faster but have a smaller mature body size. However, the changes in the body size of fish communities in the western North Pacific, which is one of the most active fishing grounds, remain unclear. This study aimed to investigate changes in the body size of fish assemblages in the western North Pacific and whether fish sizes were potentially driven by the temperature–size rule, bottom‐up effects and intra‐ and interspecies competition at a community scale. We evaluated the fish weight data of 6 stocks of 4 species from 1978 to 2018 and 17 stocks of 13 species from 1995/1997 to 2018. Weight reduction in the fish assemblage was observed in the 1980s and was associated with the biomass peak of the Japanese sardine (Sardinops melanostictus), indicating the effect of intra‐ and interspecies competition. Another weight reduction was observed in the 2010s, which was associated with a moderate increase in the biomass of the Japanese sardine and chub mackerel (Scomber japonicus). Our analyses indicate that stronger stratifications in the surface layers during the 2010s potentially reduced the nutrient supply from the subsurface to the surface layers. This limitation in food availability forced intra‐ and interspecies competition under a moderate increase in fish biomass. Our findings underscore the critical significance of integrating the impacts of species competition and climate change on fish sizes to improve fishery management at a community level. [ABSTRACT FROM AUTHOR]

Soil is home to a multitude of microorganisms from all three domains of life. These organisms and their interactions are crucial in driving the cycling of soil carbon. One key indicator of this process is Microbial Carbon Use Efficiency (CUE), which shows how microbes influence soil carbon storage through their biomass production. Although CUE varies among different microorganisms, there have been few studies that directly examine how biotic factors influence CUE. One such factor could be body size, which can impact microbial growth rates and interactions in soil, thereby influencing CUE. Despite this, evidence demonstrating a direct causal connection between microbial biodiversity and CUE is still scarce. To address these knowledge gaps, we conducted an experiment where we manipulated microbial body size and biodiversity through size‐selective filtering. Our findings show that manipulating the structure of the microbial community can reduce CUE by approximately 65%. When we restricted the maximum body size of the microbial community, we observed a reduction in bacterial diversity and functional potential, which in turn lowered the community's CUE. Interestingly, when we included large body size micro‐eukarya in the soil, it shifted the soil carbon cycling, increasing CUE by approximately 50% and the soil carbon to nitrogen ratio by about 25%. Our metrics of microbial diversity and community structure were able to explain 36%–50% of the variation in CUE. This highlights the importance of microbial traits, community structure and trophic interactions in mediating soil carbon cycling. [ABSTRACT FROM AUTHOR]