Integrative zoology最新文献

The transition of cetaceans from a terrestrial to an aquatic environment involved a crucial sensory adaptation in environments with limited visibility. Vibrissae, important mechanoreceptors, undergo an ontogenetic transformation in odontocetes. Although most lose them early in life, their follicles persist as innervated vibrissal crypts, suggesting a continuous sensory function. In some species, these crypts could function as mechanoreceptors, electroreceptors, or even be involved in magnetoreception. The Franciscana (Pontoporia blainvillei) is a species restricted to the Southwestern Atlantic Ocean. It currently faces high mortality rates due to incidental capture in gillnets, which has led to its current classification as Vulnerable. This research describes the histomorphology of vibrissae and crypts in different developmental stages. The samples were processed using routine histological techniques, immunohistochemistry, and scanning electron microscopy. In neonates, the emerging and innervated vibrissae probably are important for lactation. Subsequently, the vibrissal hair is lost or involutes , being replaced in juveniles and adults by an innervated pseudohair that likely maintains a mechanoreceptive function, although its micromorphology also suggests a potential electroreception. The maturation of the echolocation system, which allows for a broader diet, coincides with these changes in the vibrissae. This suggests that the initial mechanoreceptive structures, linked to lactation, evolve to complement hearing and foraging within low-visibility environments.

Members of the Onchocercidae family are parasites that infect a wide range of tetrapods, including wild birds and other animals. In Colombia, studies on avian blood parasites have diagnosed infections with microfilariae in several species using light microscopy. However, no morphological or molecular analyses of these nematodes have been conducted to date. The present study examined samples from 3820 wild birds with material deposited in the biological collection of the Host-Parasite Relationship Study Group since 1999. Of these individuals, 142 (3.7%) were infected with microfilaria and were analyzed using morphological and morphometric measurements. Additionally, 55 samples with blood or tissue preserved in ethanol were analyzed for sequencing of nuclear marker 18S rDNA and mitochondrial markers 12S rDNA and COI. Morphological analyses showed infection by at least one of 13 designed morphotypes of microfilariae. Twenty-nine sequences were obtained (10 of COI, 6 of 12S, and 13 of 18S), corresponding to 21 molecular lineages associated with Onchocercidae. These sequences were associated with the subfamilies Lemdaninae and Splendidofilariinae, the genera Aproctella Cram, 1931, Splendidofilaria Skrjabin, 1923, and Eufilaria Seurat, 1921, and other sequences did not cluster within any genus for which sequences were available for a particular molecular marker. These findings establish the first framework of morphological and molecular diversity of avian Onchocercidae in the megadiverse Neotropical country Colombia, expanding the known distribution of several genera and highlighting the need for further sampling of adult filariids to refine taxonomic resolution.

The Turkestan ground-jay (Podoces panderi), a corvid endemic to Central Asia's deserts and steppes, exemplifies how extreme environments drive speciation. Our study provides the first comprehensive high-resolution genomic analysis of this species, using complete mitochondrial genomes (49 individuals) to decode its population structure and demographic past. Our analyses revealed three highly divergent genetic clusters with strong geographic structure. The P. p. iliensis population (Cluster_3) showed particularly pronounced genetic distinctiveness, with significant differentiation from P. p. panderi (Cluster_2 and Cluster_1) populations. This clear genetic separation supports the taxonomic validity of P. p. iliensis as a distinct evolutionary lineage. Demographic reconstruction indicated that Cluster_2 likely represents the ancestral group, with subsequent southward expansion into the Karakum region. The isolated P. p. iliensis population exhibited signatures of long-term isolation, including reduced genetic diversity and absence of recent gene flow with other clusters. These results provide strong evidence that P. p. iliensis represents a distinct evolutionary unit. The genetic structuring into three clusters reflects historical isolation in desert refugia during Pleistocene climatic fluctuations. Notably, we detected asymmetric gene flow among three clusters. These findings redefine P. panderi as a model for desert adaptation, where climatic extremes forged genetic fragmentation amid limited dispersal. Beyond taxonomy, our work highlights how aridification sculpted biodiversity in Asia's interior, urging conservation attention for these evolutionarily distinct lineages.

The transmission of many pathogens depends on insect vectors, and these pathogens tend to manipulate vector behaviors after acquisition to enhance their spread. However, the underlying molecular mechanisms remain largely unknown. The pinewood nematode (PWN), the causative agent of pine wilt disease, primarily relies on Monochamus alternatus beetles for dispersal in Asia. The behavior of the beetle plays a crucial role in the spread of the pinewood nematode among host pine trees. Here, we investigated the behavioral and molecular effects of PWN loading on M. alternatus. Behavioral assay demonstrated that PWN loading significantly reduced beetle locomotion, with decreases in movement distance, speed, and activity duration. Comparative transcriptomic analysis of the muscle of beetles with and without PWN highlighted the disruptions in key energy metabolism pathways and pathways related to aging responses and neurodegenerative diseases. Gene co-expression network showed ATP synthase subunit alpha (ATP1), which was notably down-regulated by PWN loading, is central in energy metabolism and the aging process. The reduced ATP production in the muscles of beetles with PWN suggested ATP1 as a candidate gene required for locomotion control. RNA interference (RNAi) targeting ATP1 led to a decline in beetle locomotion, confirming its role as a key mediator of these locomotion changes. Overall, our findings revealed that the pinewood nematode manipulates vector behavior through energy metabolic genes such as ATP1 and provides potential cues for vector manipulation by the pathogen on aging and longevity.

Sweet taste is a crucial chemosensory modality for detecting natural sugar compounds, which are primarily derived from angiosperms. In vertebrates, excluding birds, sweet taste is typically mediated by the Tas1r2-Tas1r3 heterodimer, and the receptor function often reflects dietary adaptations to sugar-rich diets. To gain insight into early vertebrate dietary transitions, we identified Tas1r genes in 58 vertebrate species and one outgroup and conducted functional assays in 10 representative species spanning six major clades, including one coelacanth, two amphibians, one squamate, two turtles, two crocodilians, and one mammal. Cell-based assays showed that only the desert tortoise and American alligator exhibited detectable responses to natural sugars via Tas1r2-Tas1r3, while all other tested species showed no response. To trace the evolutionary origin of sweet taste perception, we reconstructed ancestral Tas1r2 and Tas1r3 receptors for tetrapods, amniotes, and sauropsids. Functional assays of these ancestral receptors revealed no sugar sensitivity. Integrating our results with previously published data, we conclude that Tas1r2-Tas1r3-mediated sweet taste likely originated in amniotes and did not exist in earlier-diverging vertebrates such as cartilaginous fishes, bony fishes, and amphibians. These findings suggest that sweet taste arose independently in vertebrate lineages after the origin of angiosperms, and likely represents lineage-specific adaptations to angiosperm-derived dietary resources.

Ongoing environmental changes are affecting behavioral responses of animal populations. Both warming temperatures and increased human disturbance may trigger adjustments in mammal activity patterns, for example, favoring activity switch to nighttime despite a greater risk of encountering nocturnal predators. Disentangling the relative roles of these stressors is critical for predicting the population-level consequences of environmental changes, yet the joint effect of multiple stressors is poorly understood. Here we investigated how ambient summer temperature, predators, and human presence influenced temporal responses in two herbivorous mammals (the roe deer Capreolus capreolus and the fallow deer Dama dama) across Mediterranean protected areas. By conducting intensive camera trapping (∼12,400 trapping days; 196 sites), we evaluated changes in daily activity level and nocturnality of deer species. Both herbivores reduced their daily activity with warmer temperatures, emphasizing the need to minimize thermoregulatory costs, yet only roe deer increased nocturnality following diel warming. Conversely, nocturnality of the more heat-tolerant fallow deer was only affected by wolf (Canis lupus) visitation rate, although weakly, suggesting that fallow deer traded off heat avoidance with predator avoidance. We found neither reductions in daily activity levels nor an increase in nocturnality in response to higher human visitation rate, possibly depending on our relatively undisturbed protected areas (i.e., areas with low human population density and sustainable levels of outdoor recreational activities) or the stronger effect of heat avoidance. Under the anticipated warming, species-specific consequences of these behavioral responses on population viability may be expected.

Understanding the molecular mechanisms underlying phenotypic novelties is fundamental to deciphering the evolution of biodiversity. As a pivotal driver of phenotypic divergence, gene regulation operates through multiple layers, including transcriptional dynamics and post-transcriptional modifications. Laryngeal echolocation, an evolutionary breakthrough enabling bats to occupy specialized nocturnal niches, has been instrumental in their global adaptive radiation. Here, we leverage a comparative framework of two laryngeal echolocating (Rhinolophus sinicus and Myotis pilosus) and two non-laryngeal echolocating bats (Cynopterus sphinx and Rousettus leschenaultii) to dissect the contributions of differential expression (DE) and alternative splicing (AS) in shaping this sophisticated sensory system. Integrating short-read RNA sequencing with long-read isoform-resolution data from cochlear tissues, we systematically identified differentially expressed genes (DEGs) and alternatively spliced genes (ASGs). Our multi-method validation revealed distinct regulatory signatures: Upregulated DEGs in laryngeal echolocating bats showed significant enrichment for neural function (synapse organization and neuron development), while ASGs are predominantly associated with epigenetic regulation (protein methylation, histone modification, and chromosome organization). Notably, cross-comparative analyses demonstrated a higher-than-expected overlap between DEGs and ASGs, with two key regulators (SRRM4 and MAP1B) consistently identified across all four interspecies comparisons. These conserved candidates exhibited dual regulatory modalities, suggesting their pleiotropic roles in coordinating transcriptional and post-transcriptional programs. Intriguingly, we detected varying levels of selection pressure acting on DEGs and ASGs, implying different evolutionary constraints on these regulatory layers. Overall, our findings establish that both DE and AS contribute to the molecular architecture of laryngeal echolocation, though their interplay-whether synergistic or independent-requires further mechanistic interrogation.

Sterility control is one of the key tools for regulating pest rodent population density. An in-depth analysis of the molecular mechanism of sterility caused by control agents is of great significance for further exploration of novel sterility controls and the development of alternative drugs. In this study, male plateau zokors (Eospalax baileyi) in the breeding period were tested to explore the molecular mechanism of quinestrol-induced sterility. We used RNA-seq technology to investigate key genes and signaling pathways associated with the inhibition of testicular development and spermatogenesis, and validated these findings through qPCR. The findings indicated that in plateau zokors treated with quinestrol, 420 genes were down-regulated and 127 genes were up-regulated. Notch3, Ppp2r3c, Lipe, Il1b, and Tlr2 are the potential new targets for quinestrol to affect testicular development in plateau zokors. Gene ontology (GO) analysis showed that DEGs were enriched in the inflammatory response, positive regulation of ERK1 and ERK2 cascades, and positive regulation of MAPK cascades. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that DEGs were enriched in pathways such as metabolism of xenobiotics by cytochrome P450. GSEA analysis revealed that treatment with quinestrol induced pathway changes related to the positive regulation of the ERK1 and ERK2 cascades and the positive regulation of PI3K/AKT signaling in plateau zokors. Quinestrol influences the ERK1/2 signaling pathway within the MAPK cascade in spermatogonia of plateau zokor testes via the GPER1 receptor, inducing oxidative stress and resulting in male infertility.

Brain evolution is influenced by energy constraints and ecological adaptation for bats, but the specific factors driving specialization in sensory versus cognitive brain regions remain poorly understood. By integrating morphological traits, ecological information, and neuroanatomical traits from 145 bat species, we reveal the driving mechanisms of differentiation: sensory regions (auditory nuclei and inferior colliculus) were constrained by body-size allometry, while cognitive regions (neocortex and hippocampus) were directly shaped by ecological selection. Auditory nuclei decrease in size with increasing echolocation peak frequency, suggesting functional specialization through optimized neural efficiency under energy constraints. Ground-foraging behavior drives neocortical expansion to meet the cognitive demands of complex spatial navigation. Similarly, the dietary diversity was linked to hippocampal enlargement, convergent with the adaptive evolution linking hippocampal expansion to spatial memory in birds. The total brain mass shows dual regulation-dietary diversity drives the enlargement, while the higher wing loading associated with aerial foraging suppresses expansion through metabolic constraints. These findings extend the expensive tissue hypothesis by revealing intra-brain energy trade-offs and demonstrate that ecological and behavioral selection serve as the key driver for cognitive brain region evolution. Our study has highlighted the critical need for multi-scale frameworks that integrate developmental constraints, ecological adaptation, and metabolic trade-offs to unravel brain evolution.

The evolution of limbs and tails in tetrapods has been widely studied as key traits for locomotion, balance, and evolutionary biology, but only under a "life-history" perspective, which may not explain all the morphological differences observed within this group. In this context, leveraging a dataset covering 44% of salamander species, we compared appendage proportions across families, ecological groups, and sexes within a phylogenetic framework. Plethodontidae showed shorter limbs compared to other families, while aquatic species had the opposite trend. Basal families had the shortest tails, while terrestrial species had the widest ones. Furthermore, some families showed divergence in limb proportions: Ambystomatidae had shorter forelimbs than hindlimbs, while Salamandridae had longer forelimbs than hindlimbs. Phylogeny explained most variation, but ecological adaptation and convergence also played roles. Our study confirms that animal body form is probably driven by a combination of evolutionary history and ecological drivers. We think that expanding this multi-disciplinary phylogenetic perspective to other elements of interest, such as caudal vertebral number and foot shape, may help to better understand the evolution and adaptation of appendages in Caudata.