Integrative zoology最新文献

Colour morphs in polymorphic species are associated with a suite of heritable traits governed by distinct genetic loci, each corresponding to alternative fitness peaks. Hormonal pleiotropy has been proposed as a mechanism maintaining these morphs, though experimental evidence is lacking. In this study, we tested whether white and yellow morphs of the common wall lizard (Podarcis muralis) adopt alternative strategies shaped by the immuno-competence handicap hypotheses (ICHH). Specifically, we experimentally elevated plasma testosterone levels via transdermal administration and measured changes in (i) immune response using phytohaemagglutinin (PHA) swelling and (ii) the aggressive behaviour in response to a mirror test simulating territorial intrusion. We found that testosterone-induced immune suppression was stronger in white males, while aggression decreased in both morphs. Elevated testosterone eliminated the baseline differences between morphs in both immunity and aggression. These findings provide the first experimental support for morph-specific life-history strategies in common wall lizards, consistent with the ICHH: Yellow males prioritize aggression over immunity, while white males invest more in survival at the cost of competitiveness.

The rumen microbes of large mammalian herbivores (LMHs) play a critical role in resisting the chemical defenses of plants, such as tannins, but whether fecal microbes in LMHs function in this adaptive process remains unclear. Despite ample studies over the past decade have focused mainly on bacteria, the role of fungi in the response to tannins requires more attention. Additionally, most previous studies have been restricted to captive herbivores, and we still do not know much about those in the wild. To understand the role of fecal bacteria and fungi in plant‒herbivore interactions, we first tested the response and variation in the response of fecal bacteria and fungi to different concentrations of tannin-rich food using 16S/ITS rRNA data in feeding experiments with sika deer (Cervus nippon). For wild sika deer in Northeast Tiger and Leopard National Park, we observed seasonal differences in the tannin content of their diets, which was significantly higher in spring than in autumn. Interestingly, the pattern of the fecal bacteria in wild sika deer response to tannin-rich diets was similar to that observed in the feeding experiments but showed variation in fungi. Feeding with tannin-rich diets altered the fecal microbial composition and increased the relative abundance of tannin-degrading microbes. We hypothesize that fecal bacteria and fungi may play important roles in helping LMHs adapt to tannin-rich diets. We need to further explore the function of microbes to provide important insights into the role of fecal microbes in plant chemical defenses and herbivore co-evolution.

Understanding how spatiotemporal habitat variability shapes endangered species' behavior is crucial for effective conservation. This study examined the impact of fine-scale habitat variation on four behavioral patterns (feeding, resting, social, and traveling) of the critically endangered Hainan gibbon. Year-round behavior data were collected from two groups: GC inhabiting an area with abundant food resources, and GE in a secondary forest with sparse resources. Using 135 monitoring plots, we analyzed variation in 27 habitat variables categorized into food, nutrients, plant diversity, safety and stability, and topography. Linear models revealed crown height, food plant abundance, and crude fat as key variables shaping behaviors. Higher community plant and food plant richness significantly enhanced feeding frequency, while steeper slopes increased traveling. Habitat quality variation shaped distinct behavioral strategies: in GC, feeding and resting were primarily influenced by food, social behavior by safety and stability, and traveling by plant diversity. In GE, resting, social, and traveling behaviors were mainly driven by topography, while feeding was influenced by nutrients. Likewise, food variables dominated during the dry season, whereas safety and stability, and topography variables were more important in the wet season. This study provides the first analysis of Hainan gibbons' behavioral strategies linked to fine-scale habitat variability and seasonal dynamics. The findings highlight the importance of protecting diverse habitats, as different Hainan gibbon groups exhibit distinct behavioral adaptations to their varying resource availability. This underscores the need for habitat-specific primate conservation and management in fragmented landscapes.

Identifying determinants of key phenotypic indicators driving animal population dynamics is fundamental to address measures aimed at mitigating human-wildlife interactions. In Mediterranean areas, summer drought reduces the availability of water and food resources for wild ungulates, potentially affecting body conditions. Since summer is a crucial period for the nursing/weaning of offspring, a seasonal bottleneck for ungulates would be expected to occur, especially in females. However, data on fluctuations of ungulate body mass during summer are scarce. We investigated the effects of summer progression, aridity, population density, and land use on body mass variation of adult/yearling wild boar (Sus scrofa) in a mixed forested-rural Mediterranean protected area, over a 16-year period (2007-2022). Data were gathered from individuals harvested during population control management actions, in summer. In contrast with our predictions, no consistent mass loss was observed throughout the summer. According to expectations, body mass was favored by decreasing aridity in the previous 3 months. In males, the positive effect of rainfall was mitigated by population density. Females experienced mass gain in non-arid years, mass loss in arid years, and no change in "average" years. The importance of edge habitats located at the interface between wooded and cultivated areas was confirmed by a positive relationship between female body mass and ecotone availability. The results indicate that, in a mixed forested-rural area, wild boar could maintain, or even increase, their body mass during summer. Moreover, findings emphasize the crucial role of rainfall in modulating a key driver of population dynamics for this ungulate in Mediterranean areas.

Spatial dimensions play a significant role in niche differentiation, facilitating species coexistence. Understanding how sympatric ungulates optimize habitat utilization and how they co-exist in resource-limited environments is essential for effective wildlife conservation and reserve management. Tibetan antelope (chiru, Pantholops hodgsonii), Tibetan wild ass (kiang, Equus kiang), and wild yak (Bos grunniens) are sympatric ungulates co-evolving over generations across the Tibetan Plateau, but limited information is available on their spatial partitioning and the key variables affecting both single-species and multi-species distributions. In this study, using a combination of maximum entropy model, joint species distribution models, and random forest analysis, we examined the spatial partitioning of the three ungulates and identified the critical factors influencing their distributions with their spatial distribution data collected from the Arjin Shan National Nature Reserve in the Tibetan Plateau. Our key findings: (i) Notable differences were observed in the spatial distributions of the three ungulates, with only 16% overlap in their suitable habitats. Temperature had a stronger influence on the habitat selection by chiru and kiang, whereas precipitation played a more significant role in determining the distributions of kiang and wild yak. (ii) During summer, the interspecific relationships between chiru and wild yak, and between chiru and kiang exhibited positive correlations, while the relationship between wild yak and kiang was negatively correlated. In winter, all interspecific relationships were negatively correlated. (iii) Temperature seasonality and mean temperature of the driest quarter emerged as the most critical variables influencing multi-species habitat selection. Human interference had a significantly negative impact on all three ungulate species. Our findings underscore the importance of spatial heterogeneity in facilitating species coexistence under both climatic and anthropogenic pressures, offering valuable insights for multi-species conservation planning in resource-limited ecosystems.

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.