摘要: Mammals can show conspicuous behavioral responses to thermal variation, including changes in movement patterns. We used an integrative approach to understand how environmental temperature can drive the movement behavior of a mammal with low capacity for physiological thermoregulation, the giant anteater (Myrmecophaga tridactyla). We tracked 52 giant anteaters in 7 areas throughout the Brazilian savannah. We estimated the distance moved, area used, use of forest areas, and mean environmental temperature for each monitoring day of each individual. We modeled these data with Mixed Structural Equations - considering the possible interactions between our variables and controlling for sex and body mass. Giant anteaters reduced displacement and increased forest use with decreasing environmental temperature, probably because of their low body heat production. It is possible that they reduce distance moved and area used by reducing the duration of activity. With decreasing temperature, forest habitats become warmer than open ones, besides buffer rain and chilly winds. Reducing displacement and using forests are important strategies to reduce body heat loss and the energetic costs of thermoregulation. However, decreasing movement can limit food access and, consequently, fitness. Therefore, we highlight the importance of forests as thermal shelters. With increasing frequency and intensity of extreme weather events, we showed the need to preserve forest patches to offer suitable conditions for tropical mammals' behavioral thermoregulation. In this context, policies favoring deforestation on Brazilian territory are especially worrisome. Finally, we emphasize the need of integrative approaches to understand the complex interactions between organisms and the environment.

摘要: Members of the Torpedinidae (torpedoes) and Hypnidae (coffin ray) use electric organ discharges (EOD) to stun or kill their prey before consumption. We investigated whether EOD could also negatively affect the helminth larvae infecting these preys through a surrogate model: we applied electric discharges to individuals of blue whiting, Micromesistius poutassou, that harbored live larvae of Anisakis. Larval mortality throughout a 6-h period was significantly higher in the treatment group, suggesting that EODs could significantly hamper helminth recruitment. We then tested whether torpedinids and hypnids (strong-EOD families) harbored species-poor helminth (cestode) assemblages compared with weak-EOD Torpediniformes (Narcidae and Narkidae) and other Batoidea. Based on comparisons on estimated species diversity and mean species richness of tapeworms at host individual level we found that (i) Torpediniformes had the lowest tapeworm diversity of all Batoidea orders; (ii) Torpedo spp. consistently had the lowest mean cestode richness at host individual level, and this could not be related to other host factors influencing cestode diversity in chondrichthyans, that is body size, trophic level or dietary breath. However, a preliminary comparison between strong-EOD and weak-EOD Torpediniformes did not detect clear differences of cestode richness. Thus, evidence supporting an unambiguous contribution of EODs to depauperate cestode assemblages requires further research.

摘要: Multilevel society is one of the most complex social systems in natural ecosystems and is a typical feature among some primates. Given the potential connection between social behavior and gut microbiome composition, the multilevel social system could affect the primate gut microbiome. Here, based on long-term observation (e.g. social unit dynamics, transfer, and behavior), we investigated this potential integrating 16S rRNA gene amplicon sequencing and behavior data in Yunnan snub-nosed monkeys (Rhinopithecus bieti), which possess a multilevel social group based on one male units (OMUs, each unit with several breeding females and their offspring) and all-male unit (AMU, several bachelor males residing together). We found that the mean unweighted Unifrac distance between adult males from different OMUs was significantly lower than that between adult females from different OMUs (paired Wilcoxon test, P = 0.007). There was no significant difference in the mean unweighted Unifrac distance between females within the same OMU or between females from different OMUs. These findings indicated the potential connection between the defense and invasion of social units and the gut microbiome community in wild Yunnan snub-nosed monkeys. We speculated that the resident males of OMUs displaying a significantly higher similarity in the gut microbial community than that of adult females in separate OMUs might be associated with the sexual differences in their interactions and from previously having cohabitated together in the AMU. Therefore, this study suggested that multilevel societies might have an effect on the gut microbial community in this wild nonhuman primate species.

摘要: Understanding the process of adaptation is a key mission in modern evolutionary biology. Animals living at high elevations face challenges in energy metabolism due to several environmental constraints (e.g., oxygen supply, food availability, and movement time). Animal behavioral processes are intimately related to energy metabolism, and therefore, behavioral modifications are expected to be an important mechanism for high-elevation adaptation. We tested this behavioral adaptation hypothesis using variations of motion visual displays in toad-headed aga mid lizards of the genus Phrynocephalus. We predicted that complexity of visual motion displays would decrease with the increase of elevation, because motion visual displays are energetically costly. Displays of 12 Phrynocephalus species were collected with elevations ranging from sea level to 4600 m. We quantified display complexity using the number of display components, display duration, pathways of display components, as well as display speed for each species. Association between display complexity and elevation was analyzed using the phylogenetic generalized least squares (PGLS) model. We found that both the number of display components and the average value of tail coil speed were negatively correlated with elevation, suggesting that toad-headed lizards living at high-elevation areas reduced their display complexity to cope with the environmental constraints. Our research provides direct evidence for high-elevation adaptation from a behavioral aspect and illustrates the potential impacts of environment heterogeneity on motion visual display diversification.

摘要: Benthic macroinvertebrates play key roles in shallow aquatic ecosystems and can contribute substantially to aquatic food webs. However, how macroinvertebrates with different behaviors (for example, pertaining to locomotion, foraging and burrowing) impact water quality and primary producers has not been fully explored. Here, we performed two consecutive microcosm experiments to test the effects of (1) macroinvertebrates with different behaviors (a low mobility scraper aquatic snail Bellamya aeruginosa and a high mobility shredder freshwater shrimp Macrobrachium nipponense) and (2) different shrimp biomasses on water clarity and the composition of benthic primary producers. The results showed that presence of snails significantly increased the biomass of filamentous green algae and decreased the biomass of periphyton. In contrast, presence of shrimp significantly decreased the biomass of filamentous green algae and increased the biomass of periphyton, and these effects were biomass dependent. Filamentous green algae disappeared when shrimp biomass reached 9.8 g m-2. No interactive effects of snail and shrimp presence were found. This could be attributed to different food pref-erences by the two consumers, with snails preferring periphyton (mainly diatoms) and shrimp preferring fila-mentous green algae. The presence of snails decreased water turbidity, while shrimp increased water turbidity, which showed a hump-shaped response to shrimp biomass with a peak at 24.2 g m-2. These results are likely because the snail is a low mobility grazer and can filter suspended particles, while the shrimp is a high mobility shredder with burrows, which can strongly disturb sediment. The decrease in water disturbance at high shrimp biomass might be due to food limitation, thus reducing burrowing and foraging activities. Neither snail nor shrimp affected the biomass of H. verticillata, while the biomass of V. spinulosa increased with shrimp biomass. The reason for this could be that shrimp increased nutrient availability and decreased the growth of filamentous green algae that compete with macrophytes. Our study demonstrated that different macroinvertebrates have comple-mentary functions in benthic habitats; thus, maintaining macroinvertebrate diversity is important for shallow aquatic ecosystems. Furthermore, the freshwater shrimp M. nipponense could be a potential consumer to control filamentous green algal blooms in its native range, but their biomass should be taken into consideration.