This study re-evaluates the Pleistocene history of the European hedgehog (Erinaceus europaeus) and the Northern white-breasted hedgehog (E. roumanicus), by integrating genetically verified occurrence records, complementary allopatric GBIF records and ecological niche modelling (ENM). We assessed differences in broad-scale environmental associations, identified climatic predictors associated with their distributions, and reconstructed potential past climatic suitability during the Last Glacial Maximum. Niche overlap, equivalency and similarity analyses were applied across allopatric regions and areas of sympatry. Human Footprint showed a strong signal in exploratory models for both species, with a stronger effect in the Northern white-breasted hedgehog. Climatic predictors differed between the species: predicted suitability for the Northern white-breasted hedgehog was more strongly associated with temperature-related variables, whereas the European hedgehog models were mainly influenced by annual temperature range and precipitation-related variables. Niche comparisons across the Central European (CE) and Russian–Baltic (RB) contact zones revealed contrasting patterns, with stronger realized climatic niche differentiation in the CE zone and apparently greater, but less clearly resolved, niche overlap in the RB zone. The location of the CE contact zone may partly coincide with the transition between oceanic and continental climates, consistent with the trapping hypothesis of hybrid zones. Palaeoclimatic projections indicated suitable areas beyond the classical Mediterranean peninsulas, supporting the possibility of northern or extra-Mediterranean refugial areas. Our results suggest that broad-scale environmental gradients may contribute to the spatial structuring of contact zones and may interact with species-boundary dynamics despite ongoing hybridization, while palaeoclimatic reconstructions support a more complex Pleistocene history than implied by the classical southern-refugia paradigm. These findings highlight the importance of considering both ecological and historical processes when interpreting the evolutionary history of European temperate taxa.
Mobile genetic elements drive horizontal gene transfer (HGT), which may have contributed to the functional diversity of termite gut microbiomes, although the environmental determinants of these processes remain poorly understood. Our proposed model integrates spatially resolved physicochemical gradients and mobile genetic element (MGE) dynamics to quantitatively predict HGT patterns in termite guts. The framework integrates high-resolution metabolomic and transcriptomic profiling data from gut compartments, sourced from published experimental studies, with a generalized additive model to forecast the rate of MGE transfer as a function of local environmental conditions, and goes beyond static cataloguing of HGT events. Moreover, metabolic network alignments have been used to predict MGE-host interactions based on functional complementarity, and a heterogeneous graph neural network is used to dynamically predict HGT hotspots using environmental, MGE, and microbial host data. Unlike traditional methods, our framework explicitly links microenvironmental variability with gene flow mediated by MGEs using taxonomic, metagenomic, and metabolic features. The framework incorporates state-of-the-art computational methods, such as nanoscale secondary ion mass spectrometry for spatial metabolite mapping and graph attention networks (GAT) for transfer-likelihood prediction. The study of physicochemical gradients in the context of MGE-host interactions offers a mechanistic framework for investigating HGT dynamics in complex microbial communities, with broader implications for understanding gene flow in other host-associated ecosystems.
Parental effects link parental phenotype and environmental variation to offspring performance and evolutionary trajectories. However, their role remains poorly resolved in species lacking post-oviposition care, where offspring development is shaped mainly by pre-hatching parental influences. We investigated how parental phenotype, reproductive investment, and parental relatedness were associated with offspring development in the Asiatic toad (Bufo gargarizans). Amplectant pairs were collected from the wild, and offspring were reared under standardized laboratory conditions from fertilization to metamorphosis. Parental relatedness was estimated using microsatellite markers to evaluate how parental genetic similarity was associated with offspring developmental and morphological traits. We detected positive assortative pairing by body mass in B. gargarizans and strong clutch effects across offspring developmental traits, indicating substantial among-family variation. After distinguishing among parental body size, body mass, and body condition, the most consistent associations involved paternal body condition, paternal investment, and parental relatedness. Paternal body condition was positively associated with offspring growth rate during the G25-G42 interval, suggesting faster mid-stage larval growth in offspring of males in better condition. Paternal reproductive investment was positively associated with post-metamorphic morphology, particularly tibiofibula length at G46. Parental relatedness was negatively associated with length-related morphology around metamorphosis, and this association varied among developmental stages. Maternal traits showed more limited and mainly stage-dependent associations with offspring traits. Our results show that offspring development in B. gargarizans is associated with parental phenotype, reproductive investment, and parental relatedness. Paternal body condition and paternal investment were associated with offspring growth and post-metamorphic morphology, whereas parental relatedness was negatively associated with length-related morphology around metamorphosis. These findings suggest that parental effects in this species are trait-specific and stage-dependent. They also highlight the importance of integrating paternal phenotype and parental relatedness into studies of amphibian reproductive ecology, especially in species without post-oviposition care.
Secondary adaptation of amphibians to marine environments is exceptionally rare. The crab-eating frog, Fejervarya cancrivora, is the only known amphibian capable of completing its life cycle in intertidal zones, where it faces dual challenges: high salinity stress and a diet rich in chitinous crab exoskeletons. While osmoregulatory adaptations have been well documented, the synergistic roles of the host’s digestive system and its gut microbiota in this dietary specialization remain unclear. Here, we integrated histological analysis, comparative transcriptomics, chitinase activity assays, and gut metagenomics to compare F. cancrivora with its freshwater congener, F. multistriata. We found that F. cancrivora has evolved a thicker gastric muscularis and longer gastric villi, consistent with enhanced processing of hard prey. Comparative transcriptomic analysis revealed an expanded repertoire of putative chitinase encoding transcripts (15 vs. 8 non-redundant transcripts), and both gastric and intestinal tissues exhibit significantly higher and more pH-tolerant chitinase activity. In contrast, the gut microbiota of F. cancrivora is not enriched for microbial chitin degradation genes, but instead is functionally specialized for lipid metabolism and DNA repair pathways. A controlled feeding experiment confirmed that the microbial enrichment in lipid metabolism is diet-driven, while the DNA repair pathways is largely independent of diet and likely reflects microbiome-intrinsic adaptation to chronic saline stress. Together, these findings suggest a partially partitioned host-microbiome strategy in which host manages chitin breakdown, while the microbiota optimizes energy harvest and intrinsic stress tolerance. Our findings provide a new paradigm for amphibian marine adaptation, and highlights host-microbiome functional differentiation during niche expansion. Not applicable.
Multimodal communication, in which multiple signal modalities are combined to produce a single compound signal, is employed by many species and can mediate a wide range of fitness-relevant behaviours. While the form and function of multimodal signals have been extensively studied, we know little about how individual traits such as personality and experience influence receivers’ responses to these signals. We investigated how aggressiveness and experience affect the behavioural responses to bimodal signals in the brilliant-thighed poison frog Allobates femoralis. In this species, male advertisement calls constitute a fixed bimodal signal, as the production of sound is coupled with the inflation of the vocal sac, which adds a visual cue. We presented territorial males with a synthetic advertisement call (acoustic cue) and a model frog with a pulsating vocal sac (visual cue), and manipulated signal ambiguity by varying the spatial distance between the two components. We predicted personality and experience would affect how males responded to the bimodal signal depending on its level of ambiguity, and expected younger and/or more aggressive males to respond faster and to attack the visual cue more frequently than older or less aggressive males, especially under high signal ambiguity. Contrary to our predictions, neither aggressiveness nor experience influenced response latency or attack likelihood. Instead, all males displayed a consistent population-level pattern: as the spatial separation between the visual and acoustic signal components increased, they were less likely to attack the model, and their initial and overall interactions shifted from the visual model to the sound source. These findings suggest that the fixed bimodal signals in A. femoralis selected for robust and uniform receiver responses to maintain reliable communication during high-stakes social interactions such as territorial defence. Aggressive receiver responses seem to be dual-staged, consisting of far-field phonotaxis to the acoustic signal component and visual and multimodal signals only becoming relevant during near-field aggression. Future studies should compare how ecological and social factors shape receivers’ responses across species with varying degrees of coupling between the signal components in order to better understand the evolution of multimodal signalling and of the diversity of receiver strategies.
Monitoring wildlife in remote areas is a key challenge in conservation, with traditional methods proving increasingly inadequate in the face of accelerating biodiversity loss. Uncrewed Aerial Vehicles (UAVs) or drones help bridge data gaps, but methods require careful development and validation to ensure protocols are appropriate, accessible, reproducible, and generate reliable data. Herein, we develop detailed UAV-based protocols for surveying the endangered marine iguana (Amblyrhynchus cristatus), a lizard that is endemic to the coastlines of the Galápagos Islands, Ecuador. We outline steps from image collection and processing, through locating and counting animals, before validating results against traditional methods. We find that UAV-based surveys outperform traditional ground-based surveys in terms of count reliability and effort in the field in different types of terrain and various population densities. Moreover, we show that consumer-level drones can be used effectively — even by newly trained pilots — and describe a standardised manual flying protocol that mimics automated flying whilst maintaining flexibility in the field. Finally, we recommend the use of orthomosaics (geometrically corrected, high-resolution aerial image maps) for surveys on flat terrains and 3D models (digital representations of the surface in three dimensions) for cliffs and compare several common image-processing platforms in terms of success to reconstruct marine iguanas. Our protocols advance the effective monitoring of Galápagos marine iguanas. Whilst they were specifically developed for this species, we postulate that these could be applicable for other species across the archipelago, or in coastal and open landscapes worldwide.
The hard clam (Mercenaria mercenaria) is native to the coast of the United States and Canada. Following its introduction to China, it has become an economically important bivalve species cultured in ponds. Extreme heat and hypoxia events severely impact the physiological status of marine organisms. Excess reactive oxygen species produced by environmental stress can lead to antioxidant stress response and lipid remodeling. Antioxidant stress response and lipid metabolism can reveal the response mechanism and adaptation ability of organisms to environmental changes. In the present study, coupled lipidomic and biochemical approaches were employed to reveal the response mechanism to heat and hypoxia stress at the antioxidant stress and lipid metabolism level in the hard clam. The antioxidant system was enhanced showing stress-specific to increase total antioxidant capacity (T-AOC) capacity and maintain relatively stable malondialdehyde (MDA) level. 913 lipid metabolites were identified by widely targeted lipidomic analysis. Glycerophospholipids (GP), glycerolipids (GL), and sphingolipids (SP) were the main differential expression lipid metabolites. Lipid remodeling of the gill tissue was mainly caused by GP, GL and SP metabolism in the hard clam. Activation of the antioxidant system which evidenced by elevated T-AOC, can alleviate oxidative damage, thereby preventing excessive accumulation of MDA under environmental stress. Concurrently, increased abundances of GP and SP metabolites drive remodeling of membrane lipids, which is critical for maintaining membrane fluidity and structural integrity during stress. Furthermore, the accumulation of GL metabolites functions as thermos-protectant. This study expands our understanding of hard clam responses to heat and hypoxia stress at the antioxidant and lipid metabolism level.
Abstract Different elevational gradients and anthropogenic pressures between island and mainland systems mediate discrete climatic sensitivities and distribution trends in butterfly lineages. We assess the comparative distributional changes of Pieridae (Pierinae and Coliadinae) on Taiwan Island and mainland China. Across Taiwan Island, the geographic range of Pieridae is mainly limited to lowlands due to the sharp decline in temperature with rising elevation. In mainland China, both reduced temperature and low precipitation at upper elevations shape Pieridae’s spatial pattern. Across Taiwan, both subfamilies showed positive associations with human disturbances at greater elevations, while Pierinae showed a positive relationship with thick vegetation cover at lower elevations. Throughout mainland China, Pieridae exhibited negative associations with human disturbances and vegetation density at higher elevations. According to the MaxEnt results, across Taiwan Island, elevation is mainly responsible (80.6%) for the distribution of Pierinae, while maximum temperature of warmest month (Bio5) is mainly influencing (53.7%) the distribution of Coliadinae. Initially Pierinae exhibited an increase in highly suitable regions across the three historical periods, followed by a decrease. Conversely, Coliadinae showed an initial contraction, followed by an expansion. Future global warming may result in a reduction of highly appropriate habitats for both subfamilies without significant evidence of upslope migration. Most Pieridae species are projected to undergo habitat contraction, resulting in decreased species diversity. These outcomes indicate stronger ecological constraints and higher vulnerability to Pieridae diversity in island systems, highlighting the necessity of implementing regional conservation strategies.
Abstract Background In ants, morphological variation is particularly important, as it constitutes a key mechanism underlying the division of labor. Despite this, relatively few studies have addressed the proximate cellular mechanisms responsible for worker size variation. Endoreduplication represents a promising contributor to morphological diversity, as it is a process with a well-established cellular basis. Methods In this study, we investigated whether endoreduplication can account for variation in body size in monomorphic ants, analogous to patterns previously reported in polymorphic species. We tested whether body size correlates with the level of endoreduplication in workers of three monomorphic ant species that differ in ecology, colony structure, and life-history traits. The analysis showed that individual worker size was positively correlated with nuclear DNA content (C-value), both in the overall linear mixed-effects model (LMM) and in species-specific analyses. As an additional finding, the C-value level exhibited body-part specificity, reaching the highest values in the abdomen. Conclusion Our results demonstrate that endoreduplication contributes to body size variation not only in ants with distinct worker subcastes, but also in species with subtle size variability. This suggests that endoreduplication represents an evolutionarily ancient and potentially widespread mechanism, which may have served as a developmental foundation for the evolution of advanced polymorphism in ants.
Abstract Background Correlated evolution refers to the coordinated changes of multiple traits during species evolution. Fish skin exhibits diverse structures comprising the epidermis, dermis, scales, epidermal mucous cells (EMCs), and epidermal club cells (ECCs), yet the correlated evolution among these components remains unexplored. ECCs are classically hypothesized to be the source of chemical alarm cues in ostariophysan fishes, which are passively released during predator-inflicted skin damage to alert nearby conspecifics of active predation threats, this process known as the alarm response. However, we identified two critical exceptions from 53 freshwater fishes: naked carp ( Gymnocypris , ostariophysans) have lost ECCs, while mandarin fish ( Siniperca , non-ostariophysans) have acquired them. The established link between ECCs and alarm responses in ostariophysans may be confounded by phylogeny. Their consistent co-occurrence does not establish a causal relationship. The two evolutionary exceptions serve as ideal models to test this relationship. Results We investigated correlated evolution across seven core skin structures, including epidermal thickness, dermal thickness, scale thickness, EMCs size/number, ECCs size/number in 53 freshwater fishes. Analysis revealed significant correlated evolution among skin structures. Epidermal thickness showed positive correlations with all other metrics, except for the relationship between scale thickness and EMCs number. Scale thickness exhibited antagonistic correlations with both epidermal and dermal thickness. Notably, scale thickness positively correlated with EMCs number, reflecting functional adaptation to reduce inter-scale friction. Critically, behavioral experiments demonstrated that naked carp, despite lacking ECCs, exhibited robust alarm responses. Furthermore, we tested six close relatives of the naked carp, all of which possessed ECCs and exhibited robust alarm responses. Conversely, mandarin fish, despite possessing ECCs, showed no alarm responses. This evidence does not support ECCs as the necessary source of chemical alarm cues. Conclusions In conclusion, our study demonstrates significant correlated evolution among core skin structures in freshwater fishes. Crucially, we challenge the prevailing paradigm by showing that chemical alarm cues can originate from integumentary components other than ECCs, evidenced by the robust alarm response in ECCs-lacking naked carp. Secondly, ECCs may play a multifunctional role evidenced by the absence of alarm response in ECCs-possessing mandarin fish. These insights advance our understanding of fish skin functional morphology and ecology.
Abstract Background Mosquito-borne diseases remain a major global health challenge, highlighting the need for eco-friendly alternatives to conventional chemical insecticides. This study aimed to evaluate a tiered in silico screening framework to prioritize plant-derived essential oils as potential sustainable mosquito control agents. Results A large-scale virtual screening of 5,183 essential oils was conducted, followed by toxicity-based filtering, yielding 1,345 low-toxicity candidates. Subsequent molecular docking against neural targets of Culex pipiens identified 51 top-priority oils. Among these, German chamomile (Matricaria chamomilla) consistently appeared across multiple chemotypes. The Egyptian German chamomile essential oil was selected for experimental validation. Chemical analysis revealed sesquiterpenes, particularly bisabolol oxide derivatives and β-farnesene, as major constituents. Docking results demonstrated strong binding affinities toward multiple neural targets. Larvicidal bioassays showed 100% mortality at 400 ppm after 24 h, accompanied by significant behavioral, morphological,and histopathological abnormalities. Neurochemical assays indicated increased acetylcholinesterase activity, alongside decreased γ-aminobutyric acid levels, suggesting disruption of neural signaling. Conclusions This study demonstrates the effectiveness of in silico screening in identifying safe and potent plant-based mosquito control agents. German chamomile essential oil emerges as a promising eco-friendly candidate for sustainable vector management, warranting further field-based validation.
Abstract Hydrogen peroxide (H 2 O 2 ) is a crucial signaling molecule in vertebrate regeneration, yet its functional role across diverse lizard species remains incompletely defined. This study elucidates the master regulatory function of H 2 O 2 during tail regeneration in the lizard Scincella tsinlingensis using integrated pharmacological, morphological, histological, and transcriptomic approaches. Pharmacological modulation revealed that H 2 O 2 markedly enhances regeneration, achieving 5.89 ± 0.69 mm tail length at 21 days post-amputation (dpa), whereas ROS inhibition severely impairs regenerative outgrowth (0.88 ± 0.07 mm). Transcriptomic analysis at 7 dpa demonstrated that H 2 O 2 establishes fundamentally distinct molecular trajectories, with only 5 common differentially expressed genes (DEGs) shared between the DMSO-vs-APO (713 DEGs) and DMSO-vs-H 2 O 2 (593 DEGs) comparisons. Functionally, H 2 O 2 synchronizes three core pathways—phagocytosis, immune regulation, and cellular motility—into an integrated repair program while temporally coordinating MAPK, mTOR, Wnt, and Hippo-YAP signaling cascades. This establishes a sequential regulatory framework where the immediate post-amputation period constitutes an H 2 O 2 -dependent critical window with limited plasticity, explaining the only partial rescue achieved with delayed intervention. Transcriptomic data further suggest inferred associations of NADPH oxidase 2/DUOXA2-derived H 2 O 2 with cellular proliferation, YAP1 expression, potential EMT (via HIF-1α), as well as G2/M arrest and chromatin remodeling. These findings support the paradigm that ROS act as evolutionarily conserved, spatiotemporal integrators of tissue repair, coordinating injury response, immune modulation, metabolic reprogramming, and developmental pathway activation. This work provides a mechanistic foundation for developing redox-based therapies aimed at enhancing regeneration in clinical contexts of impaired healing.
Abstract Background The circumpolar green sea urchin, Strongylocentrotus droebachiensis, exhibits a fascinating behaviour, termed “covering”, which consists of coating the body with materials collected in the environment. The lack of a consensus about the drivers of covering in green sea urchin and their relative importance prevents accurate predictions about the frequency and intensity of the behaviour and its functional consequences in a globally changing ocean climate. We paired an experiment in an oscillatory wave tank with green sea urchins collected from an extensive sea urchin barren in southeastern Newfoundland (Canada), and a 3-mo survey of this barrens, to examine individual and interactive effects of wave action, light, sea urchin body size, and types of covering materials on sea urchin’s displacement and covering. Results Our findings establish that covering in S. droebachiensis is: (a) predominantly controlled by hydrodynamic forces, with the existence of water current-induced covering tipping points; (b) ontogenetically determined, with a continuous inclination to cover in small individuals and a seasonal component to covering in larger individuals; (c) opportunistic, with multiple types of covering materials employed based on availability; and (d) functionally costly, as it significantly reduces mobility. We largely rule out the paradigm that light induces covering or at least clearly marginalize it as a trigger or effector. Our results and those of other studies of the behavioural repertoire of S. droebachiensis , are consistent with the notion that covering serves a complementary function to mitigation of hydrodynamic forces. Conclusions We propose that covering in S. droebachiensis primarily serves a mechanical protection function, whereby the species shields its body surface to protect its external sensory, defensive, and locomotory organs against physical contact with moving debris.
Monopisthocotylan parasites have been proposed as tags for studying host population structure due to their direct life cycles and short generation times. However, their effectiveness in reflecting host population connectivity remains under scrutiny. The poorly-understood connectivity of fisheries stocks in Lake Tanganyika, the second deepest lake in the world with a permanently stratified, relatively species-poor and well-delimited pelagic zone, serves as a case-study to test utility of parasites for fish stock identification. This study investigates the population structure of two Kapentagyrus species parasitizing dorosomatid fish in Lake Tanganyika, by analyzing variation in mitochondrial protein-coding genes across a geographic gradient. The study comprised 12 population genomic datasets from the central and southern subbasins of the lake sampled within the same week to account for host migration. We observed differences in geographic population structure of the two parasite species, with restricted gene flow in Kapentagyrus limnotrissae infecting a single dorosomatid species and smaller hosts preferring the littoral zone. Conversely, K. tanganicanus exhibited no geographical structure, reflecting its broader host range and preference for larger hosts preferring the pelagic zone. The results also highlight that other mitochondrial genes such as those from the dehydrogenase family or atp6 provide higher resolution for population genetic studies in these parasites than the frequently used cox1. The study also compared two sequencing strategies—individual versus pooled sequencing (PoolSeq)—for assessing population structure of monopisthocotylan parasites, and found that PoolSeq yielded similar results with lower demands on individual DNA quantity and sequencing costs. This work supports the use of host-specific, directly transmitted parasites as ecosystem tags and provides valuable insights into the role of host ecology and parasite life-history traits in shaping population dynamics.
BACKGROUND:Biological catapults as power amplification systems are widespread across diverse taxa, known for their evolutionary significance and effectiveness in various ecological contexts. Although praying mantises are renowned for their predatory behavior, typically involving a directly muscle-driven, grasping-like motion to capture prey, a strongly altered movement sequence is observed in Haania orlovi. The moss mantis exhibits a spear-like foreleg morphology and a significantly different ultrafast impaling hunting strategy. RESULTS:This system generates a mass-specific power output, surpassing the limits of direct muscle contraction. Through comprehensive morphological analysis (micro-computed tomography, scanning electron microscopy), combined with high-speed videography and force measurements, we provide evidence for a latch-mediated spring actuation (LaMSA) system, enabling this ballistic motion. The mechanism involves elastic energy storage in the deformed cuticle of the proximal trochanter, supported by latch-like interlocking. Confocal laser scanning microscopy revealed specialized cuticle composition in the trochanter, facilitating energy storage. For further validation, we developed a 3D-printed proof-of-concept model, incorporating a deformable spring-like double-spiral structure, demonstrating the functional advantage of the LaMSA system in generating high-speed movements. CONCLUSION:This study not only elucidates a novel predatory mechanism in mantises but also contributes to our understanding of evolutionary adaptations in predator-prey interactions. Illustrating the essential mechanical components in a physical model, and the compact, load-responsive dual functionality of the described power amplification system, potentially serves as inspiration for advancements in bio-inspired engineering solutions. Our findings highlight the importance of integrated biomechanical analysis in uncovering novel biomechanical mechanisms, demonstrating potential for significant functional shifts through seemingly minor morphological modifications.
Abstract Background Understanding and predicting the dynamics of rodent populations, particularly for endangered or pest species, requires knowledge of potential background factors. We collected long-term data on the abundance of European ground squirrels, Spermophilus citellus, in 64 colonies as part of the Hungarian Biodiversity Monitoring System to investigate the abiotic factors that could explain the spatial and temporal dynamics of populations in Hungary. We used information theory-based modelling and multi-model inference to investigate the effects of environmental and climate variables on relative population densities, using monitoring records of burrow counts as proxies for density collected annually between 2000 and 2018. We examined data carefully for any clues of inconsistencies, errors, or missing data, which resulted in 57% of the complete dataset. Results Our generalised additive models (GAM) with splines identified geographical location, year, and principal components reflecting winter temperature, precipitation, and summer temperature to affect population densities. Contour plots derived from the best GAM model uncovered increasing density in the Kiskunság and Kisalföld meso-regions with favourable water management characteristics and decreasing densities in the northern and southern regions, which in fact, cover floodplain of River Tisza and other flash-flood regions. Ambient temperature and precipitation of the wettest and warmest months during hibernation and summer contributed most to counts fluctuations, though these factors were dwarfed by spatial effects. Increased temperatures and aridification in the Kiskunság, because of the warming Pannonian ecoregion, seemed to positively affect counts. Conclusions Analysis of our reduced dataset indicated unidentified local factors or a spatial effect on demographic variability of ground squirrel populations. Those fluctuations underscore the necessity of research and management on local populations to identify the reasons of declines and adapt management accordingly to stop or change decreasing population trajectories.
Predation risk imposes fundamental trade-offs between survival and reproduction, often leading to sex- and age-specific differences in anti-predator behaviour. We investigated these trade-offs in the jumping spider Saitis barbipes, a species in which cryptic females and juveniles contrast with conspicuously coloured males that engage in courtship displays. Using high-quality in-focus and blurred predator images, we tested first behavioural responses and reaction distances of adult males, adult females, and juveniles. While all groups reliably recognised predator cues, adult males consistently approached stimuli more closely before showing anti-predator behaviour and frequently responded with courtship rather than defensive behaviours. In contrast, females and juveniles more often employed passive strategies such as freezing. Stimulus clarity had no effect on the type of response, whereas distance strongly influenced behavioural responses. These results indicate that predator recognition is innate, but response thresholds are context-dependent and shaped by sex, age, and reproductive role. Conspicuous adult males appear to suppress or delay anti-predator responses in favour of courtship, highlighting an evolutionary trade-off between reproductive effort and survival.
Dopamine is one of the best-known neurotransmitters found in most animals. Among the major roles that this mediator plays in many organisms is the regulation of motor skills, behavior, and feeding. Its localization in the central (CNS) and peripheral nervous systems (PNS) has been well studied mainly in vertebrate animals, but remains poorly understood in invertebrates such as mollusks of the class Bivalvia. Nevertheless, bivalves are of particular interest for their nervous system that has undergone a number of simplifications due to the sedentary lifestyle. As shown in the review, the key functions of dopamine have been retained in this group, with, however, a shift towards regulation of effector organs and physiological processes. The interaction between serotonin and dopamine, which regulates the degree of motor activity, nutrition, and locomotion, also deserves special consideration. There still remains a vast number of unresolved issues concerning the effects that dopamine exerts in the bivalve CNS, its role in the regulation of larval development and behavior of adults. This review summarizes the major known aspects of dopamine, including its localization and role in the life history of bivalves.
BACKGROUND:The insect yellow gene family plays crucial roles in cuticle pigmentation, waterproofing, courtship, molting, and eggshell development. However, the specific physiological function of yellow-e3 remains unclear. RESULTS:In this study, we first generated yellow-e3 mutant drones using CRISPR/Cas9, achieving mutation rate of 87.4%, primarily (61.6%) comprising 5-bp deletions. But no discernible phenotypic differences were observed in these mutants. We therefore performed RNAi knockdown by injecting yellow-e3 siRNA into 2-day-old pupae, which significantly reduced eclosion rate (36.14 vs. 72.53% in controls). Individuals that failed to eclose were arrested during molting, unable to shed the pupal cuticle, and exhibited overall yellow cuticles. Eclosed adults, by contrast, showed normal cuticle coloration. Further analysis revealed that non-eclosed individuals had significantly upregulated expression of ecdysone signaling genes USP and E75, but downregulated E74, accompanied by markedly reduced expression of melanin synthesis genes (TH, yellow-y, and tan). These changes ultimately disrupted melanin deposition, leading to cuticular yellowing. CONCLUSIONS:We propose that genetic compensation may conceal phenotypic defects in CRISPR-generated mutants. This study provides the first evidence that silencing yellow-e3 in A. mellifera disrupts molting, reduces the eclosion rate, and inhibits cuticular melanization.
