Integrative zoology最新文献

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.

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.

Precise quantification of the parasitic load during infections is necessary for a deep understanding of parasite-host interactions. Haemosporidians, an order of intracellular blood parasites, including agents of avian malaria and their closer relatives, have two organelles, remnants of endosymbiosis: the mitochondrion and the apicoplast, which have their own extranuclear genomes (nucleoids). While the number of organelles per parasitic cell appears to be stable, the number of their nucleoids is not, but the dynamics and factors affecting them still remain to be elucidated. We used a set of 71 blood samples of migratory birds infected by haemosporidian parasites to quantify relative DNA quantities of these two organelles through real-time quantitative PCR (qPCR). We investigated the congruence of these two parameters with the microscopically detected number of parasites, for all samples measured and for the subset of those with moderate to high parasitemia. We found that apicoplast DNA content was a better predictor for intermediate infection intensities, while mitochondrial DNA content was a better predictor for acute infections. This difference may result from the regulation of parasite intra- and inter-organellar genomic content throughout the infection stages in vertebrate hosts. Our work contributes to the methods for quantification of blood parasites in wildlife and to the understanding of their development and conservation-relevant consequences for the avian hosts.

Amphibians host a diverse array of macro and microparasites, and these relationships can provide relevant information for assessing and monitoring population and ecosystem health. The dynamics and outcomes of these host-parasite interactions are influenced by several biotic and abiotic factors, as well as by the characteristics of both the parasite and the host. This study aims to identify hemoparasites in Pleurodema thaul (four-eyed frog) (Leptodactylidae) across its extensive distribution in Chile and to explore potential relationships between parasite occurrence, host traits, and habitat variables. To achieve this, we surveyed P. thaul populations from 40 localities between the extreme north and south of Chile (22-43°S), in a latitudinal gradient of 2500 km. In each locality, individuals were actively searched along the margin of water bodies, manually captured, sexed, and measured using standard morphometric and biosecurity protocols. Blood samples were collected via facial vein puncture using needles and heparinized capillary tubes. Smears were prepared on-site, fixed with methanol, and stained with 10% Giemsa for subsequent microscopic analysis at 40× and 100× magnification. Hemoparasites were detected in 61% (221/363) of individuals, with three genera identified: the hemogregarines Hepatozoon sp. and Dactylosoma sp. (Adeleorina), with a prevalence of 7% and 39%, respectively, and the hemococcidium Lankesterella sp. (Eimeriorina), with 22%. The study describes the key characteristics of these parasites in both intra- and extracellular developmental stages. These findings contribute to the understanding of anuran hemoparasites by expanding knowledge on their distribution, morphological traits, and local and regional host-parasite interactions.

Avian blood parasites of the genera Plasmodium, Haemoproteus, and Leucocytozoon are typically identified through Sanger sequencing of a partial cytochrome b fragment, the MalAvi barcoding region. This approach limits the detection of mixed infections and the relative frequencies of co-infecting parasites. In contrast, next-generation sequencing (NGS) can resolve these problems but has been underused for haemosporidian lineage identification in samples from the wild. We used an improved PCR protocol and sequencing with Illumina MiSeq to determine haemosporidian assemblages in wild birds captured at a migration stopover site in Bulgaria, Europe. From 406 samples obtained from 52 bird species, we detected 81 haemosporidian lineages in 131 infected samples from 32 species (32% prevalence). On average, individuals were infected with 2.4 lineages, with 59 birds infected by a single lineage, and 21 birds infected with 5-9 lineages. A subset of samples was Illumina- and Sanger-sequenced in parallel, finding mixed infections in 72 samples and 8× higher detection rate of mixed and co-infections through high-throughput sequencing. Both methods identified the same dominant (co-infecting) lineage (91%). Metabarcoding identified common mixed infections of sister lineage groups ("sisterhoods") known for prevalent lineages and morphospecies, including Plasmodium relictum p_SGS1, Haemoproteus motacillae h_YWT2, and Haemoproteus parabelopolskyi h_SYAT01. Some other lineages appeared consistently more dominant. Our study shows that in some host communities, metabarcoding can reveal a great diversity of mixed infections. This opens new horizons to the study of assemblages of haemosporidian parasites, their interactions within individual hosts, and co-evolution with other members of the blood microbiome and the hosts.

Evolutionary and behavioral adaptations are frequently linked to animal sensory perception. Echolocators have evolved instantaneous and highly adaptive control over their sensory and motor actions enabling them to detect and capture rapidly moving, evasive prey in three-dimensional space. Specifically, among volant bats, maneuverability decreases with increasing mass, while toothed whales and dolphins have evolved tight turning rates and radii to enable them to capture small and elusive fish. We thus hypothesize that selection pressures should have driven the evolution of relatively smaller body size among echolocators to enhance their agility. To test this, we conducted PGLS and GLMM model analyses comparing the body mass of 1327 echolocating species with 4878 non-echolocating species. In support of our body size filtering hypothesis, echolocating species tended to be significantly smaller than their non-echolocating relatives across the entire body mass range, both generally and at the order and family levels. Furthermore, our findings transcended the concurrent effects of habitat type and dietary preferences on modulating body size distributions, as well as ecogeographical rules relating to the evolution of body size. This shows that the echolocator-body size relationship has evolved independently across vertebrate taxa that diverged millions of years ago. Nevertheless, the resultant diversity of extant, relatively small echolocating species and the key functional roles they play in ecosystems may be vulnerable to contemporary anthropogenic disturbances.

The diversification of advertisement calls is largely driven by climatic niche differentiation. Our results provide acoustic evidence for studies on ecological speciation in anurans.