Integrative zoology最新文献

Amphibians worldwide are declining due to various anthropogenic and environmental stressors. One of the most important threats is large-scale epidemics of chytridiomycosis, which is caused by Batrachochytrium dendrobatidis (Bd). Unlike in other continents, amphibian species in South Korea, such as Pelophylax nigromaculatus, are resistant to Bd, making it difficult to discern its detailed effects. This study determined the dynamics of Bd infection in P. nigromaculatus by integrating physiological, microbiological, and morphological data and applying state-of-the-art machine learning methodologies. Data are presented on Bd prevalence, body size, weight, and physiological stress responses, including corticosterone (CORT) levels and innate immune functions determined using bacterial killing assays and skin microbiome composition. Significant physiological differences between infected and non-infected animals were observed regarding elevated CORT levels and changes in bacterial killing capacity. Skin microbiome analysis indicated a subtle variation in the microbial composition, but the alpha and beta diversities did not significantly differ between infected and non-infected animals. To balance the intrinsic class imbalance of the dataset, several machine learning methods were coupled with different data-augmentation techniques. Using the Light Gradient Boosting Machine resulted in the best predictive performance when considering conditional generative adversarial networks-augmented datasets. Among the predictors, CORT level and bacterial killing ability were chosen for classifying the infection status. Machine learning can be used to complement the contrasting sensitivities of multi-level biomarkers due to differences in disease resistance or infection loads. This integrated approach may be essential for understanding the impacts of multiple threats to amphibians.

Maintaining the body's water balance is crucial for function and survival in all animals. Humidity conditions vary between different habitats and greatly affect an animal's evaporative water loss (EWL). Species inhabiting arid regions have adaptions to minimize water loss, which those adapted to life in humid regions may lack. Therefore, the physiology of species from different habitats could respond differentially to acute exposure to dry conditions. We measured the EWL and resting metabolic rates (RMRs) of 12 Israeli squamate species, from either mesic or xeric habitats, spanning four orders of magnitude in size. We treated the animals to dry and humid air simulating natural conditions (vapor pressure deficits 3 and 1 kPa, respectively) at an ecologically relevant temperature of 25°C. EWL rates were higher in dry air, and the effect was stronger in mesic species. EWL of mesic species in humid air is similar to EWL of xeric species in dry air, indicating similar EWL when tested under settings that match each species' natural conditions. In dry air, the RMR of small-bodied (<5 g) mesic species increased, whereas those of some small-bodied xeric species decreased. Small mesic species might be displaying stress from unnaturally dry conditions, whereas small xeric species possibly display an adaptation to minimize EWL by lowering RMR, thereby respiration rates. Physiological measurements are usually taken in dry air, and our results suggest previous experiments may contain a methodological bias. Future ecophysiological research needs to consider ambient humidity, by either varying experimental humidity to match natural conditions, or considering possible effects of humidity during analysis and interpretation of experiments and models.

Myrmecophagy is one of the most common types of dietary specialization among predators. It can include exploitation of ants, termites, or both. Although ants and termites share a few traits, they are distantly related and possess different defensive mechanisms. Therefore, adaptations to ants and termites should differ, especially in arthropod predators of similar body size as their prey. We investigate offensive and defensive adaptations in Zodariidae spider genus Diores, reported to feed on termites. The ancestral state reconstruction of the diet favored termitophagy for the genus, but metabarcoding analyses revealed that only one of the four studied Diores species fed exclusively on termites. The remaining three species captured both ants and termites. Interestingly, the laboratory observations of a single species, Diores poweri, revealed a similar attack-and-retreat strategy to catch both termites and ants. Three ant species and one termite were successfully captured with a similar frequency, but the capture of Hodotermes termites was more efficient. The paralysis of Hodotermes by D. poweri was approximately 20 times faster than by an ant-eating spider Zodarion nitidum, which correspond to venom composition differences between the species. The habitus of D. poweri resembles the size, shape, movement, and the coloration of its predominant prey, Camponotus maculatus ants, suggesting Batesian mimicry. However, the modeling of the visual discrimination of coloration by potential lizard and bird predators revealed that Diores might be distinguished from Camponotus. Our results suggest that Diores spiders are specialized myrmeco-termitophagous predators, possessing effective adaptations and exploiting ants for defense.

Seahorses and their relatives (syngnathids) exhibit remarkable diversity in morphology and function, characterized by their distinctive body shapes and specialized feeding mechanisms. Despite recent advances in uncovering the genetic basis of some traits, the genotype-phenotype map in syngnathids remains incomplete. In this study, we employed forward-genomic approaches and developed a method to enrich for human disease amino acid loci at a genomic scale. Our aim was to identify genetic loci associated with fin size reduction, tooth loss, and spinal curvature in syngnathids. Intriguingly, we identified a convergent amino acid change in the lat4a gene shared by syngnathids and some flying fishes, with in vitro analysis confirming its role in fin size evolution in both lineages. While genes critical for tooth development are conserved in syngnathids, the absence of key regulatory elements, such as pitx2, likely contributes to tooth loss. Additionally, we implicated col6a3 in spinal curvature development in seadragons. These findings reveal novel genetic signatures and developmental constraints underlying syngnathid diversity, demonstrating the utility of comparative genomics and targeted gene enrichment in exploring vertebrate evolution.

A significant fraction of the genomes of most multicellular eukaryotes includes extensive arrays of tandemly repeated sequences, collectively referred to as satellite DNAs (satDNAs). However, the mechanisms responsible for generating and maintaining varying satDNA abundances across lineages and temporal scales are still unclear. This work focused on arowana fishes (Teleostei, Osteoglossiformes) as a model; their widespread intercontinental distribution and basal phylogenetic position within Teleostei make them a compelling model for evolutionary research, especially in the realm of satDNA molecular evolution. Through the integration of genomic and chromosomal data, we analyzed and compared the catalogs of satDNA families (i.e., satellitomes) of four out of the six extant arowana species, elucidating ancestral evolutionary trends and establishing their temporal history. Arowanas displayed a small number of satDNA families, ranging from 16 to 25 in Osteoglossum bicirrhosum and Scleropages formosus, respectively. Alongside the identification of some shared satDNAs, many considered species-specific, nonetheless possess a limited number of copies in other species. The minimal variation observed both within and across species highlights the long-term conservation of satDNAs during evolution, since specific ones (referred to as long-term conserved satDNAs) may have endured throughout a lengthy evolutionary period. Moreover, fluorescence in situ hybridization (FISH) investigations conducted with the most abundant satDNAs demonstrated unique hybridization patterns for homologous orthologous ones, signifying their dynamic genomic positioning. Besides, the similarities of satDNAs among species align with their phylogenetic relationships, showing the high dynamism of arowanas' satDNAs, with several evolutionary events driving their sequence diversity.

Senescence is defined as a chronological decline in demographic performance with age, showing a gradual deterioration of body functions and a related decline in survival. We analyzed biometric data from over 31 000 Alpine chamois (Rupicapra rupicapra L.) culled during 12 consecutive hunting seasons in 28 hunting districts with different geological substrate (calcareous, metamorphic, and siliceous) in Central-Eastern Alps (Italy). Available data confirmed that females experienced a later senescence than males, in terms of loss in eviscerated body mass. This is in accordance with a greater energy expenditure undergone by males in rut period. Interestingly the different geological substrate influenced the final body mass and the decline of body functions of chamois living in different areas. A pivotal role in this process seems to be played by tooth wear. The progressive wearing of the cheek teeth was assessed in a subset of 596 mandibles using the height of molars and their height/breadth ratio. Referring to the same sex and age, the wear progress on calcareous substrate is slower than the one on other substrates. Indeed, siliceous and metamorphic substrates hold meadows with higher resistance to mechanical stress due to the presence of opal silica and lower nutritional quality compared with calcareous ones. As a consequence, life expectancies and population dynamics depend on the substrate where the chamois population lives. Enhancing knowledge about environmental factors that can affect individual biometrical characters and senescence should be considered a priority to improve adaptive management of hunting species, as well the different distribution of the hunting classes and quotas.

China stands as a global hotspot for cuckoo diversity and their avian hosts, presenting an unparalleled natural laboratory for investigating brood parasitism and co-evolutionary dynamics in avian systems. Through an extensive synthesis of published literature, verified media reports, and meticulously curated visual documentation contributed by citizen scientists, we present a comprehensive update on cuckoo-host diversity and their intricate ecological relationships across China. Our study identifies 17 cuckoo species, with 15 confirmed as brood parasites exploiting an extensive network of 142 host species spanning 74 genera and 34 families within the passerine assemblage. While we observed broad overlaps in the ranges of host body mass and egg volume across different cuckoo species, phylogenetic generalized linear mixed models reveal significant patterns of adaptive matching in both body mass and egg volume parameters between cuckoos and their respective hosts. Our findings demonstrate striking specificity in host selection, with minimal overlap in actual host species utilization among sympatric cuckoos, suggesting sophisticated niche partitioning strategies to mitigate interspecific competition. Nevertheless, critical knowledge gaps persist, particularly regarding the evolutionary dynamics of egg phenotype mimicry in relation to specific host species. Finally, we introduce a real-time tracking program designed to engage citizen scientists in ongoing documentation of parasitism events, facilitating dynamic updates to host-parasite records.

Global climate change has heightened heat stress, threatening amphibian and reptile survival, including turtles. Although turtle species vary in heat tolerance, the molecular mechanisms behind these differences are not well understood. This study aimed to identify differentially expressed genes (DEGs) in response to heat stress (32°C) versus normal temperature (25°C) in eight tissues (brain, heart, intestine, liver, lung, muscle, spleen, and stomach) of two turtle species: Platysternon megacephalum (low heat tolerance) and Trachemys scripta elegans (high heat tolerance) using RNA-seq. The results revealed significant down-regulation of genes involved in energy and lipid metabolism in P. megacephalum, suggesting metabolic suppression under heat stress. Furthermore, the jumonji and AT-rich interaction domain containing 2 (JARID2) gene, which regulates cell proliferation and differentiation, was up-regulated in all tissues of P. megacephalum but down-regulated in all tissues of T. scripta elegans under heat stress. Pathway analysis revealed that protein processing in the endoplasmic reticulum was significantly enriched in brain, heart, lung, and muscle tissues of P. megacephalum, with BiP, CHOP, NEF, and HSPs significantly up-regulated in brain tissue, highlighting this pathway's impact on heat stress response. Seven hub genes were identified in the protein processing in the endoplasmic reticulum pathway in P. megacephalum. In contrast, T. scripta elegans showed a moderate response, with up-regulation of ribosomal genes in the brain to enhance protein synthesis and folding, while down-regulation of cell cycle genes in the intestine helped conserve energy for cellular repair. No significant pathways were found in other tissues of T. scripta elegans. These molecular responses in T. scripta elegans likely contribute to its better adaptation to heat stress. This study provides new insights into the molecular mechanisms of heat stress adaptation in turtles, offering valuable knowledge for understanding their ability to cope with future climate change.

Snakes possess unique functional traits—such as venom system, reproductive mode, and dietary specialization—that regulate ecosystems and enhance resilience. This commentary highlights their role in maintaining food web stability and emphasizes the need to integrate snake functional diversity into conservation strategies under global change.

Plants interact complexly with herbivores and diverse microbial communities, both plant-associated and insect-associated. A recent study investigated how the endophytic fungus Trichoderma, colonizing tomato plants, affects the herbivore Spodoptera littoralis. The study revealed that Trichoderma-enhanced plant resistance significantly reduced larval performance by profoundly changing the insect's gut microbial community composition. This work demonstrates that the effects of plant fungal colonization on insect herbivores are critically mediated by the insect's gut microbiota, highlighting a key mechanism in plant–insect–microbe tripartite interactions with implications for sustainable pest management.