Abstract The forest musk deer (Moschus berezovskii), an endangered species in China, faces significant challenges in population recovery, particularly among young individuals in captivity, due to Eimeria infections. This study investigated the effects of oral supplementation with Lactobacillus plantarum P-8 and Lactobacillus casei Zhang on parasite infection, gut microbial succession, predicted microbiota maturity, and faecal immune markers. Twenty juveniles were randomly assigned to a control (CT) or probiotic (PB) group and monitored longitudinally across four developmental phases (hiding, conflict, maternal separation, and independent). Generalized linear mixed-effects models showed no significant effects of probiotic supplementation on Eimeria prevalence or oocyst counts. Gut microbial diversity and community composition changed markedly across developmental phases, whereas probiotic supplementation had no significant overall effect. A Random Forest-derived microbiota maturity model explained 46.56% of the variation in the response variable and indicated phase-specific differences in predicted microbiota maturity between treatment groups. Overall, host developmental stage was the primary factor associated with gut microbiota development, while probiotic supplementation was associated with modest, phase-specific differences without altering the overall successional trajectory. These findings provide insights into gut microbiota development and may inform microbiota-based management strategies for captive forest musk deer.
Abstract Appendage loss in crayfish can induce physiological stress, fitness consequences, or be fatal. While the ecological importance of chelipeds (claws) is well documented, the impact of losing other appendages remains understudied. Furthermore, there are almost no records of injury rates for other appendages in stocking conditions. This study evaluated the frequency of appendage injuries in a laboratory stock of marbled crayfish (Procambarus virginalis) and experimentally tested their importance for oviposition performance. First, we assessed stock individuals for appendage injuries, body size, and reproductive stage. Second, we conducted a controlled experiment in which we removed one or both fifth pereiopods to analyze the impacts on ovulation timing, fecundity, and spatial egg distribution along the pleon. In stock analysis, claw status, rather than body size, was significantly associated with appendage status. The loss of one or both claws initiated a vulnerability cycle, increasing injury rates, especially in the antennae and the 4th and 5th walking leg pairs. Injury rates also fluctuated within reproductive stages. In the experimental manipulation, the loss of the fifth pereiopod did not significantly impair fecundity, delay ovulation,while effects on egg distribution were minor and inconsistent. Compensatory behaviors likely maintain successful egg attachment and distribution despite fifth-pereiopod loss.
Abstract Migratory birds experience diverse ecological conditions throughout their migratory range that can influence survival, particularly during vulnerable life stages such as juveniles. Identifying the life stages and regions that constrain populations is therefore essential for migratory species of conservation concern, including aerial insectivores. Using a migratory population of red-necked nightjars (Caprimulgus ruficollis) as a model, we analyzed 12 years (2010–2021) of capture–recapture data to estimate sex- and age-specific annual survival probabilities and assessed the effects of time (year), vegetation development (normalized difference vegetation index [NDVI]), and land surface temperature (LST) in the breeding (Doñana) and nonbreeding staging areas (Mali and Guinea). Survival probabilities remained constant throughout the study period. Adults showed higher survival (females: 0.660 ± 0.038 standard error (SE), 95% confidence interval [CI]: 0.581–0.731; males: 0.677 ± 0.037 SE, 95% CI: 0.6–0.746) than juveniles (females: 0.398 ± 0.040 SE, 95% CI: 0.323–0.479; males: 0.352 ± 0.036 SE, 95% CI: 0.285–0.426), after accounting for age-specific differences in recapture probabilities. NDVI did not affect survival. In contrast, LST in both Doñana and Guinea was positively associated with survival in adults and juveniles. Our findings demonstrate that climatic factors operating in geographically distant regions can jointly shape red-necked nightjar demography and suggest that this species may be relatively resilient to projected increases in temperature.
Abstract Altruistic maternal behavior is widespread among mammals, yet its underlying evolutionary mechanisms and driving factors remain to be thoroughly investigated. Building upon previous observations of altruistic care behavior in Père David's deer (Elaphurus davidianus) in response to distress calls from non-related offspring, we designed a series of playback experiments to test several hypotheses explaining altruistic maternal behavior: the lack of kin recognition hypothesis, the "move-on" defense hypothesis, kin selection theory, reciprocal altruism, and the "learning to mother" hypothesis. Our results revealed that maternal responsiveness to calf distress calls was significantly influenced by whether the calf accompanied its mother: when it did, response intensity was significantly lower, whereas when separated, females responded indiscriminately to calls from both own and alien calves. These findings indicate that the allomaternal care behavior observed in Père David’s deer is consistent with the "lack of kin recognition" hypothesis, and neither the other observational data nor playback results supported the alternative hypotheses. These findings enhance our understanding of ungulate altruism and suggest future research should systematically explore evolutionary mechanisms driving diverse motivations for altruistic maternal behavior across species, considering varied environmental pressures and social structures.
Abstract In many bird species, plumage ornamentation plays a crucial role in mate choice by signaling individual quality. Plumage coloration may also signal reproductive success and parental effort, a key driver of offspring recruitment. In a wild population of saffron finches (Sicalis flaveola), a socially monogamous species with delayed plumage maturation in both sexes and biparental care, we captured, monitored, and video-recorded breeding pairs using nest boxes. We examined whether social class (based on age- and sex-dependent plumage coloration) signals body condition and wing ectoparasite load and whether plumage color (yellow or dull) is related to parental effort of paired females and males. We also assessed whether nesting success was associated with post-hatching parental effort and plumage color. Yellow females had better body condition than dull individuals, and yellow birds of both sexes had fewer wing ectoparasites. Males showed greater parental effort when paired with dull females, whereas females tended to invest more when paired with yellow males. Females contributed more to parental care than males, but nesting success was unrelated to plumage class or parental effort. These results suggest that yellow plumage in saffron finches signals female body condition and wing ectoparasite load in both sexes and may influence parental investment by mates.
Abstract Male trimorphism refers to the stable differences in external morphology such as body sizes and mandible shapes among male individuals, which is relatively rare in nature and usually related to alternative reproductive strategies. However, the fighting behavior of trimorphic stag beetle males with a female present has been less studied. Dorcus hopei Saunders, 1854 (Coleoptera; Lucanidae) exhibits male trimorphism, with alpha males having the largest mandibles, beta males having intermediate-sized mandibles, and gamma males having the smallest mandibles. In this study, we examined the fighting behavior of trimorphic D. hopei males in the presence of a female in the laboratory. We used a camera and BORIS software to observe and quantify males’ latency period, frequency of active attacks, duration of fighting, and the time to reach the female. Alpha males adopted a fighting strategy, exhibiting the shortest latency period, the highest probability of combat escalation, the highest frequency of active attacks, and the longest fight duration; beta males adopted a sneaking strategy; gamma males adopted a female-mimicry strategy, showing the lowest probability of combat escalation, the lowest frequency of active attacks, and the shortest fight duration. Our results indicate that the trimorphic D. hopei males exhibit 3 distinct fighting styles in the presence of a female. This study clarifies the dynamic relationship between the morphology and behavioral strategies of male D. hopei, providing an insight for understanding the coevolutionary mechanism of morphological polymorphism in lucanidae species.
Abstract Chromosome-level genome assemblies offer novel insights into the molecular mechanisms driving adaptive evolution. Beyond revealing macroevolutionary trends, these resources enable precise detection of fine-scale intra-chromosomal rearrangements. Here, we analyzed 16 chromosome-scale genomes, including 11 Vespertilionidae species, to investigate cryptic structural variation in karyotypically conserved lineages (2n = 44) across four Myotis and two Pipistrellus bats using whole-genome alignment. We uncovered widespread intra-chromosomal rearrangements, predominantly inversions, accounting for 0.49–3.13% of the genomes. Multiple large inversions (>1 Mb) encompassed genes involved in antiviral innate immunity (e.g., TRIMs, NLRPs, IRF3). We further investigated molecular adaptations linked to distinctive traits in Vespertilionidae and detected multiple positively selected genes (PSGs) and dynamically evolving gene families associated with antiviral defense and immune specialization. These include PSGs (CDK13, NUP93, SND1) and expanded gene families (NLRP1, GZMs) related to virus tolerance. Immune specialization was reflected through PSGs such as ACE, ADAM17, NDFIP1, IL27RA, and TNIP1, along with expanded families including TRIMs. Many of these genes also contribute to cancer-resistance pathways, suggesting pleiotropic adaptations that may support bat longevity. Additionally, genomic signatures of urban adaptation were identified, encompassing traits such as pollution resistance (PSGs: XPA, DNMT3B; expanded family: TAS2Rs) and photoperiod adaptation (PSGs: GPR179, ABCA4). In light of existing literature, this study highlights that comprehensive comparative genomic analyses (especially inferences of gene family evolution) require highly continuous and accurate genome assemblies, which are essential for reliably identifying candidate genetic drivers of adaptive evolution.
Abstract Temperature is one of the most critical environmental factors influencing the physiology, ecology, and evolution of eukaryotes. As a group of single-cell protists, ciliates exhibit sensitivity to temperature fluctuations. However, their transcriptional and posttranscriptional responses to temperature stress remain unknown. Blepharisma sinuosum is a widely distributed ciliate with robust temperature adaptability. Here, we use comparative transcriptomic analyses to reveal its response strategies to temperature stresses. The results indicate that 1) under high-temperature stress, B. sinuosum tends to reduce energy expenditure and enhance its capacity to correct misfolded proteins; 2) B. sinuosum takes endocytosis and degradation of nonessential proteins to maintain cellular homeostasis in cold environments; 3) metabolic levels gradually decrease and signal transduction is progressively strengthened when temperature changes (either higher or lower); 4) splicing errors are detected under temperature stress; and 5) the regulatory mechanism of alternative splicing is not obviously connected with the transcriptional regulatory mechanism. These findings reveal how ciliates respond to temperature stress and provide new insights into the survival strategies of eukaryotes under variable environments.
Abstract Accelerating biodiversity loss highlights the urgent need for effective conservation measures, and the recovery of crested ibis (Nipponia nippon) can serve as a useful model. We analyzed a 17-year dataset from a captive population at Dongzhai National Nature Reserve, China, comprising 5,893 body mass records from 257 individuals across 9 generations. Using quantitative genetic tools (Animal Model), we found that body mass exhibited significant heritability (h2 = 0.54). As for growth curve parameters, growth time-scale parameter a (h2 = 0.30) and growth-rate coefficient b (h2 = 0.23) were also significantly heritable, while the heritability of potential maximum weight M was relatively low (h2 = 0.05). Estimated breeding values for body mass showed an increasing intergenerational trend, though this did not differ significantly from expectations under genetic drift. Importantly, the heritability of these traits enables the establishment of a personalized expected growth trend based on parents and healthy siblings. The comparison revealed that healthy offspring closely followed parental growth trajectories, whereas unhealthy individuals showed observable deviations. Considering the multiple breeding attempts throughout the lifetime of this long-lived species, cumulative historical data could help refine these family-specific baselines, providing a practical reference for monitoring individual health and allowing timely veterinary interventions.
Abstract Understanding the drivers of patch visitation in agricultural landscapes is essential for maintaining pollinator-mediated agroecosystem services, yet the extent to which behavioural mechanisms influence pollinators’ visitation rates has received little attention. Using an individual-based modelling framework (BEE-STEWARD), I examined how inadvertent social information (ISI) use and a recently documented pesticide-induced foraging bias influence nectar and pollen visitation rates of buff-tailed bumblebees (Bombus terrestris) to crop patches located near or far from the colonies. Simulations showed that ISI use primarily increased nectar visitation to all crop patches and pollen visitation to nearby crop patches, whereas foraging bias increased pollen visitation to all crop patches and nectar visitation to nearby crop patches. However, the two behavioural parameters had no interactive effects on crop visitation rates during nectar or pollen foraging. Despite the pronounced shifts in visitation patterns, total resource collection and colony demographics, including colony growth and reproductive output, remained largely unaffected. Overall, results indicate that ISI use and foraging biases are important drivers of spatial foraging patterns in bumblebees. Incorporating such behavioural pathways into pollinator foraging models may improve predictions of spatial visitation patterns and resource exploitation across agricultural landscapes, with potential implications for pesticide risk assessments.
Abstract Navigating structurally complex environments often requires assessing whether an opening affords safe passage, a task that presupposes relying on an internal representation of body size. Evidence for such awareness has been reported in mammals and birds and may also occur in other vertebrates and invertebrates. We investigated this ability in the tortoise Testudo hermanni, a species that often encounters dense vegetation and narrow passages. We first assessed the tortoises' ability to distinguish between 2 apertures of different widths. Surprisingly, they discriminated only when one aperture was twice as wide as the other, a performance markedly lower than that reported in other species. We then examined whether tortoises chose an aperture based solely on its suitability for their body size rather than by comparing the 2 apertures. However, tortoises chose the narrower opening at similar rates regardless of whether it was passable and persisted in attempting passage even when it was inadequate. When examined in a different context, food quantity discrimination, tortoises exhibited the same lack of selectivity. Overall, our findings suggest that T. hermanni does not rely on body size when negotiating obstacles, possibly reflecting poor visual discrimination capacities or the evolution of alternative strategies for overcoming physical barriers.
Abstract For group-living animals, behavioral synchronization might represent a strategy to increase survival in varying environments. However, synchronization patterns and the driving factors remain largely unknown, particularly for species living in harsh conditions, such as waterbirds in winter. From October 2023 to March 2024, we recorded videos of foraging flocks of Tundra Swans (Cygnus columbianus) in grassland, mudflat, and shallow water habitats at Shengjin Lake, China, and quantified behavioral synchronization through 2 metrics: time synchronization rate (TSR, the proportion of time spent in synchronized states) and behavioral transition synchronization rate (BTSR, the proportion of synchronized behavioral transitions). Generalized linear mixed models were used to assess the effects of spatial position within flocks, time of year, and habitat. Within flocks, swans that were close to one another showed significantly higher TSR and BTSR than those further apart. TSR but not BTSR significantly decreased over winter. Habitat type influenced BTSR, with less synchronization in shallow water habitats than in grasslands and mudflats. In addition, the negative impact of interindividual distances was more pronounced in the shallow water habitat. The findings support the idea that synchronization is the result of copying the behavior of close neighbors. Furthermore, environmental factors like time of year and habitat type can also modulate synchronization. These findings enhance our understanding of the adaptive role of behavioral synchronization in Tundra Swans inhabiting dynamic wetland habitats.
The de novo establishment of epigenetic modifications plays a pivotal role in gene expression, maintaining genome stability and cell differentiation. Tetrahymena thermophila provides an attractive model for studying de novo establishment of epigenetic modifications, as its developing new macronucleus (MAC) undergoes extensive epigenetic reprogramming during the sexual process of conjugation. Nevertheless, the coexistence of the new MACs with the parental MACs and new micronuclei (MICs) within the same cell, as well as parental MACs and MICs in non-mating cells within the same culture, has hindered detailed studies. To address this issue, we developed an optimized purification strategy including initial enrichment of new MACs by differential centrifugation, followed by further purification using fluorescence-activated cell sorting. With this two-step approach, we ultimately obtained new MACs with over 99% purity. This method will provide a crucial foundation for leveraging the new MAC to dissect the de novo establishment of epigenetic marks and their potential regulatory roles.
Abstract Aspidogastrea is the most likely candidate for the sister group to all other Trematoda (“basal” radiation). However, genomic resources for this lineage remain scarce, so the evolutionary history of trematodes remains only partially understood. We sequenced the mitochondrial genomes (mitogenomes) of two aspidogastreans, Aspidogaster ijimai and Aspidogaster conchicola, and combined them with 51 available Trematoda mitogenomes to address methodological uncertainties in phylogenetic reconstruction and assess whether mitogenomic data also support Aspidogastrea as the “basal” radiation. Through a systematic evaluation of dataset types (nucleotide/amino acid), outgroups (Monogenea/Cestoda), partitioned/nonpartitioned datasets, evolutionary models (assuming sequence homogeneity/heterogeneity), and different multi-locus sequence analyses methods (concatenation/multispecies coalescent), we demonstrated that (1) some outgroup choices caused long-branch attraction artifacts; (2) partitioned datasets improved the performance of standard (“homogeneous”) models; (3) multispecies coalescent method was heavily influenced by outgroup effects; (4) CAT-GTR model was the most robust to systematic errors. The CAT-GTR model consistently produced phylogenies of Trematoda that were congruent with the nuclear genomic (nDNA) topology at major nodes (deep phylogenetic level), with Aspidogastrea as the “basal” radiation, and all major lineages (order and suborder) monophyletic, aside from the paraphyletic suborder Xiphidiata. We further used the CAT-GTR mitogenomic topology and the nDNA topology to establish a time-calibrated phylogeny of Trematoda. The two datasets placed the Aspidogastrea–Digenea divergence at ∼246–360 and ∼271–446 Ma, and the Diplostomida–Plagiorchiida divergence at ∼216–306 and ∼213–347 Ma, respectively.
Abstract Predatory attacks are difficult to observe in nature, and thus, researchers use model predators to simulate real predators. However, few studies have systematically compared the response of prey to models versus living predators. We flew a trained live raptor across mixed species flocks of Amazonian birds and compared the acoustic and behavioral response of individual species and the entire flock to that following a flight of a painted model glider. We found no statistically significant differences between treatments in alarm call bandwidth 50%, duration 90%, latency for most species, or the proportion of species producing alarm calls. A significant overall treatment effect was detected for alarm call frequency, 75%, although this was not driven by any specific species and was small in magnitude. The number of urgent notes showed a marginal trend toward fewer notes in model trials. Latency to call differed between treatments overall, driven by White-flanked Antwren, which called more rapidly to the live hawk than to the model. About one-third of flock species responded with alarm calls, a proportion that did not differ between treatments. Models can indeed be an effective method to study anti-predator behavior, but more research on how and why species may or may not discriminate between models and live predators is warranted.
By mimicking a bacterial infection in free-ranging bats to induce sickness behavior, the study showed that lactating bats do not interrupt their foraging activities. Maternal care prevails. When animals become sick, some behavioral changes occur that have an adaptive value to fight the infection. Non-reproductive captive and free-ranging mammals exhibit anorexia, weight loss, fever, and lethargy when bacterial infection is imitated with a lipopolysaccharide (LPS) challenge. Anorexia leads to a reduction of caloric and nutrient intake, which might represent a serious conflict when the animals is involved in reproductive activities. Lactation is the most expensive period for reproductive mammals due to the costs of mammary tissue development, milk production and parental care. We tested to what extent free-ranging lactating females of the fish-eating myotis Myotis vivesi modulated sickness behavior in their foraging activity when exposed to LPS. We placed GPS tags on lactating females in Partida Norte island, Gulf of California, Mexico in June 2019. We administered a dose of LPS and a dose of saline on separate nights to each individual, and we monitored their foraging activity on each trial. We found no significant differences between the 2 treatments in total flight time length, foraging flight time length, commuting flight time length, total flight distance, and flight speed. Our study demonstrated that behavioral changes associated with the infectious process in free-living mammals may be compromised when they must sustain activities that are key for population survival.
Abstract Mate choice is a key driver of reproductive fitness and a central topic in behavioral ecology. Although integrating behavioral observations with paternity analyses can provide powerful insights into mate choice, such combined approaches remain rare in non-human primates. Here, we conducted a 1-year study on a free-ranging troop of Taihangshan macaques (Macaca mulatta tchelinesis) in northern China. Using behavioral observations and microsatellite genotyping, we examined female mating patterns via Friedman tests and compared offspring numbers among male rank/age groups via Kruskal–Wallis tests. Female copulations were biased to high-ranking and prime-aged males, and paternity was also biased toward these males. Notably, one low-ranking immigrant male and inferred extra-group males also achieved reproductive success. Although male–male competition possibly contributed to the observed biases toward high-ranking/prime-aged males and the success of immigrant/extra-group males, our observations of sexual interference suggested that female choice also played an important role. Females likely preferred high-ranking males for direct benefits (e.g., resource access and protection) and prime-aged males for their higher reproductive capacity. In addition, novel (new immigrant or extra-group) males may also have a reproductive advantage, reflecting female strategies to increase offspring genetic diversity or avoid inbreeding. Our findings revealed complex female reproductive strategies and contribute to the understanding of sexual selection in primates.
The recent expansion of grey wolves (Canis lupus) in Italy has led them into new ecological contexts, including areas characterized by poor prey communities and landscape anthropization. While dietary studies are essential for predicting wolf’s ecological functions and impacts, it remains unclear whether research on wolf diet has kept pace with this expansion. We mapped the current distribution of wolves in Italy and then clusterized areas based on food resources available to wolves: domestic or wild ungulates, the coypu (Myocastor coypus), and resources associated with landscape anthropization. Finally, we checked the coverage of each cluster by dietary studies (n = 33). Areas currently inhabited by wolves in Italy include nine different food resource assemblages. However, most studies on wolf diet have focused on remote areas of the Alps, where northern chamois and red deer are abundant, and in areas with a rich assemblage of wild ungulates. In contrast, wolf diet remains unexplored in Mediterranean ecosystems with poorer ungulate assemblages and in highly anthropized landscapes, despite these environments together accounting for most areas of ongoing wolf expansion. These gaps may preventing us from knowing if wolves in highly anthropized landscapes are exposed to toxic compounds and if predation on domestic pets can trigger conflicts. Similarly, the lack of research in areas where wolves rely almost exclusively on wild boar hinders our ability to predict the potential impact of African Swine Fever on wolf ecology and behaviour, as well as its broader influence on human-wolf conflicts.
Predators are generally classified into two types based on feeding strategies: dietary specialists and generalists. Specialist predators exhibit prey-handling behaviors adapted to specific prey types. In snakes, earthworm-feeding has evolved independently multiple times, resulting in the presence of both specialists and generalists among earthworm-eating species. Nevertheless, studies on prey-handling behavior of earthworm-feeding snakes remain limited. We compared prey-handling behavior of two colubrid snakes, an earthworm-feeding specialist, the Ryukyu green snake (Ptyas semicarinata) and a generalist, the Japanese keelback snake (Hebius vibakari), by feeding them earthworms. Ptyas semicarinata swallowed earthworms with minimal lateral jaw movements and exhibited significantly shorter prey-handling time than H. vibakari. The swallowing behavior of P. semicarinata partially differed from typical jaw-walking and is likely an adaptation to earthworm prey. The movements of the earthworms appeared to facilitate ingestion in P. semicarinata. Future studies employing CT imaging and functional analyses of cranial morphology may help elucidate the mechanisms underlying this rapid swallowing behavior.
