Inter-individual Distances Research Articles

Contact call acoustic structure is associated with inter-individual distances during antiphonal vocal exchanges in wild red-tailed monkeys (Cercopithecus ascanius schmidti)

Abstract Contact calls allow animals to maintain group cohesion when visibility is restricted. To maximise call detection, animals should produce calls that are audible to closest neighbours or respond to individuals that produce preceding calls (i.e., antiphony). Antiphonal exchanges are more likely to occur between older conspecifics that respond more reliably or close neighbours that are more likely to detect calls when groups are travelling. Because animals should produce calls that are optimised for propagation, call structure should be associated with the distance between individuals calling in antiphonal exchanges. I investigated whether acoustic structures of red-tailed monkey (Cercopithecus ascanius) contact calls (phrased grunts) reflected increased sound propagation as nearest neighbour distances increased, depending on three factors: (1) the occurrence of a preceding grunt, (2) neighbour age-sex class, and (3) group travel speed. I recorded grunts from five habituated monkey groups at Kibale National Park, Uganda. Per grunt, I measured five parameters associated with sound propagation. Grunt mean entropy and frequency related negatively to neighbour distance when the neighbour produced a preceding grunt or when there was no preceding grunt, but not when a more distant individual grunted prior. Neighbour age-sex class and group travel speed did not influence whether grunt structure was associated with neighbour distance, but monkeys produced grunts with higher mean entropy and frequency as groups travelled faster. Variation in grunt mean entropy and frequency was associated with propagation to either nearest neighbours or more distant individuals that produced preceding calls, providing quantitative evidence for antiphonal calling. By calling antiphonally, animals in cohesive groups can spread out to avoid intra-group competition while maintaining contact with other group members. Higher grunt entropy and frequency as groups travel faster may counteract more variable sound attenuation as animals move through acoustically complex (e.g., densely vegetated) environments.

Group characteristics and spatial organization of the Eastern Beaufort Sea beluga whale (Delphinapterus leucas) population using aerial photographs

While it is known that beluga whales ( Delphinapterus leucas (Pallas, 1776)) are social animals, sociality within populations remains complex and poorly understood. Using aerial photographs taken in mid-July and early August 2019, we examined group characteristics and spatial organization of the Eastern Beaufort Sea beluga population in two distinct summering areas: (1) the continental shelf and offshore region of the southeast Beaufort Sea and (2) the inshore of the Mackenzie Estuary. Observations revealed that the mean group size was similar in both environments. A piecewise regression analysis showed that belugas were found to be most frequently within 24.6 m of another beluga in the offshore and within 22.0 m in the inshore. The mean interindividual distance of groups composed of subadults and (or) adults was greater than that of groups including younger whales in both environments. Also, the swimming direction of individuals in a group differed less in the offshore than in the inshore. We suggest that habitat shapes the types of activity conducted and that spatial cohesion within groups persists across environmental conditions but changes with age composition. By identifying elements of social structure and important areas for Eastern Beaufort Sea belugas, our results highlight the value of habitat conservation.

High Exploration Behavior of Termite Propagules Can Enhance Invasiveness

Social life is usually associated with enhanced propagule pressure, which increases the chance of introducing several individuals during a single introduction event. Social insects are therefore among the most successful invasive species, benefiting from rapid establishment and increased foundation success in new habitats. In termites, propagule pressure may also be increased by the development of reproductive individuals from a small group of foraging workers. This suggests that enhanced exploration activity may increase propagule pressure through an elevated chance of transporting isolated groups of foragers. Here, we analyzed the exploration behavior of three termite species of the Reticulitermes genus, comparing the invasive species Reticulitermes flavipes (testing both native and introduced populations) to the native species Reticulitermes grassei and Reticulitermes lucifugus. Different features representative of the exploration capacity were measured during 48 h, including: the number of tunnels, the length of tunnels, the number of foragers, and the interindividual distance of foragers in a straight line or through tunnels. Our results show that compared to the native Reticulitermes species, R. flavipes foragers from both populations dug more tunnels with a longer total length, and individuals were more spatially dispersed and covered a larger exploration zone. These findings suggest that the enhanced exploration ability of R. flavipes may have played a role in its invasion success, by increasing its propagule pressure through a higher chance of human-mediated transport. In addition, the absence of differences between the native and introduced populations of R. flavipes suggests that the exploration behaviors facilitating the worldwide invasion of this species originated in its native range.

Studying feral horse behavior from the sky

Unmanned aerial vehicles, commonly known as drones, have become widely available in recent years. A drone provides a bird’s eye view, which is useful in detecting and observing wild animals. One strength of imagery obtained by a drone is that it enables the capture of the two-dimensional spatial relationship of animals on the ground. I and colleagues have investigated the spatial relationships of feral horses at both intra- and inter-group levels. At the intra-group level, the distribution of the inter-individual distance of horses follows a certain pattern, indicating repulsion and attraction forces taking place among group members, similar to those in a school of fish, flock of birds, or swarm of insects. At the inter-group level, multiple unit groups aggregate to form a herd, suggesting the existence of a multilevel social structure. Automation of the analysis of the recordings of a drone, including target animal detection, individual identification, and motion tracking, presents a way forward. Drones and other emerging technologies will enhance our understanding of swarm behavior both in vivo and in vitro.

Effect of storage temperature and flash-freezing on salivary microbiota profiles based on 16S rRNA-targeted sequencing.

The sample storage environment affects gut microbial profiles as assessed using 16S rRNA sequencing. However, the influence of storage condition on human salivary microbial profiles has not been well characterized. Here, we performed an observational study to assess the robustness of microbiota profiles in three different storage environments (-80°C after flash-freezing, -80°C, and -15°C; all for 14 days) compared to immediate DNA extraction using the MiSeq Illumina platform. Notably, the 16S rRNA V1-V2 region amplicon sequencing revealed no difference in microbiota profiles between the immediate extraction and each of three storage conditions. An almost perfect correlation was shown between the immediate extraction and the -15°C storage group for relative abundance at the genus and operational taxonomic unit levels. The intraindividual UniFrac distances among storage methods were significantly shorter than those of interindividual distances. None of the amount of extracted DNA, the α-diversity indices, or the relative abundance at the phylum/genus/operational taxonomic unit level differed among storage methods. These findings indicate that a storage temperature of -15°C without flash-freezing may be optimal in terms of cost advantage and simplicity in 16S rRNA sequencing-based salivary microbial research.

The Effects of Cranial Orientation on Forensic Frontal Sinus Identification as Assessed by Outline Analyses.

Simple SummaryFrontal sinus patterns are unique amongst individuals. When faced with an unknown decedent, investigators can compare the frontal sinus pattern observed in postmortem radiographs to antemortem radiographs of the suspected individual to make a positive identification. Ideally, the antemortem and postmortem radiographs are oriented in the same exact position, but this can be challenging. This study investigates how slight variations in radiographic orientation affect sinus outlines and potentially impact identification. Frontal sinus models were created from CT scans (21 individuals) and digitally oriented across three clinically relevant views. From each standard orientation (looking straight ahead), eight 5° deviations were obtained in horizontal (left/right), vertical (up/down), and diagonal (e.g., left-up vs. right-down) directions. Within and between individual differences in sinus size and outline shape were assessed. Sinus breadth remained relatively stable across deviations, while sinus height was affected by small vertical deviations. Although radiographic vertical deviations resulted in statistical differences, impacts on outline matches were minimal. However, practitioners need to take particular care in matching radiographic orientation for smaller and/or discontinuous (right and left sides separated) sinuses, which are more likely to lose part of the sinus in more inferiorly oriented views and, thus, could affect various methods of sinus identification.The utility of frontal sinuses for personal identification is widely recognized, but potential factors affecting its reliability remain uncertain. Deviations in cranial position between antemortem and postmortem radiographs may affect sinus appearance. This study investigates how slight deviations in orientations affect sinus size and outline shape and potentially impact identification. Frontal sinus models were created from CT scans of 21 individuals and digitally oriented to represent three clinically relevant radiographic views. From each standard view, model orientations were deviated at 5° intervals in horizontal, vertical, and diagonal (e.g., left-up) directions (27 orientations per individual). For each orientation, sinus dimensions were obtained, and outline shape was assessed by elliptical Fourier analyses and principal component (PC) analyses. Wilcoxon sign rank tests indicated that sinus breadth remained relatively stable (p > 0.05), while sinus height was significantly affected with vertical deviations (p < 0.006). Mann–Whitney U tests on Euclidean distances from the PC scores indicated consistently lower intra- versus inter-individual distances (p < 0.05). Two of the three orientations maintained perfect (100%) outline identification matches, while the third had a 98% match rate. Smaller and/or discontinuous sinuses were most problematic, and although match rates are high, practitioners should be aware of possible alterations in sinus variables when conducting frontal sinus identifications.

湿热河谷芭蕉群落优势物种空间分布格局与竞争对称性研究

PDF HTML阅读 XML下载 导出引用 引用提醒 湿热河谷芭蕉群落优势物种空间分布格局与竞争对称性研究 DOI: 10.5846/stxb202010192657 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 中央级公益性科研院所基本科研业务专项（GYZX210302）；生态环境部自然保护地监管支撑专项：生态环境部生物多样性调查、观测与评估专项 Spatial distribution pattern and competitive symmetry of dominant species in Musa sp. community in the hot and humid river valley Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:竞争关系的对称性是塑造植物物种空间分布格局和影响物种共存重要机制之一，对其开展研究不仅对于揭示植物群落构建机制具有重要意义，也有助于解析群落演替的驱动力。在贵州赤水湿热河谷内的芭蕉群落中建设固定样地，对1989棵植物个体进行空间定位和物种识别并记录胸径等个体属性。采用对数相关函数和标记变异系数分析（marked variogram）等空间统计方法检测优势种的空间分布格局和竞争对称性，结果如下：（1）芭蕉（Musa sp.），粗糠柴（M.philippensis），粗叶木（L.chinensis），川钓樟（L.pulcherrima），红果黄肉楠（A.cupularis）等5种优势种均表现为小尺度下的种内聚集分布，其中芭蕉主要采用克隆繁殖，其重要值达33.6%，且种内聚集度最大。（2）芭蕉种群在5 m尺度下呈现出显著的种内对称性竞争，这一竞争过程减少了种群自疏作用并推动种内聚集分布格局的形成，增加了该种群在森林中的生存力。（3）芭蕉与其余4种优势种之间的不对称竞争过程导致了种间负关联。结果表明，不同优势种在种间竞争对称性上的差异说明了植物种群繁殖和扩散方式是群落构建的重要影响因素之一，相比于有性繁殖过程，采用无性克隆繁殖的植物个体可通过种内对称竞争机制来减少自疏以增加种群生存力，并通过与相邻异种个体的不对称竞争过程来提升种群获取有限资源的能力，进而成为演替中的优势个体。研究结果可为今后制定植物物种多样性保护政策提供科学参考。 Abstract:The symmetry of competitive relations is one of the important mechanisms affecting plant biodiversity. Its research is of great significance not only to reveal the plant community assembly mechanism, but also to explain the driving factor of community succession. A plot was established for investigation in the hot and humid river valley of Chishui city, Guizhou province. The 1989 individual plants with diameter at breast height (DBH) over 1 cm were spatially located and identied at the species level. Attributes of individual plants such as diameter at breast height size and tree height also were recorded by investigation. The spatially statistical methods including pair-correlation function (PCF) based on inter-individual distances and marked variogram function (MVF) based on individual diameter at breast height were used to detect the spatial distribution pattern and potential competitive relationship of dominant species. The analysis showed that (1) the spatial distribution patterns of the five dominant species (Musa sp., M. philippensis, L. chinensis, L. pulcherrima, and A. cupularis) showed an aggregated distribution at a small scale. The importance value of Musa sp. in the constructive species reached 33.6% and the spatial aggregation was the largest. (2) The population of Musa sp. showed significant intra-specific symmetric competition at the 5 m scale. This competition process reduced the intensity of the population's self-thinning and promoted intraspecific aggregation distribution patterns, and increased the viability of the population in the forest. (3) The asymmetric competition process between Musa sp. and other four dominant species resulted in negative interspecific associations. The differences in the symmetry of interspecific competition among different dominant species indicated that the mode of plant population reproduction and diffusion was one of the important factors affecting the process of assembly pattern and competition. Compared with the sexual reproduction process, the clonal propagation of plant individuals could reduce self-thinning to increase population viability through intraspecies symmetric competition mechanism. In addition, it could also enhance the ability of the population to obtain limited resources through asymmetric competition with neighboring heterogeneous individuals, and eventually become the dominant tree in the process of interspecies asymmetric competition. Therefore, it is suggested that in the future, we should strengthen the relevant basic research on the spatial distribution pattern and competition relationship of plants with clonal propagation, and deeply understand the relationship between asymmetric competition process and biodiversity loss during forest secondary succession. The results can provide a scientific reference for formulating plant species diversity protection policies. 参考文献 相似文献 引证文献

Disruption of Metapopulation Structure Reduces Tasmanian Devil Facial Tumour Disease Spread at the Expense of Abundance and Genetic Diversity.

Metapopulation structure plays a fundamental role in the persistence of wildlife populations. It can also drive the spread of infectious diseases and transmissible cancers such as the Tasmanian devil facial tumour disease (DFTD). While disrupting this structure can reduce disease spread, it can also impair host resilience by disrupting gene flow and colonisation dynamics. Using an individual-based metapopulation model we investigated the synergistic effects of host dispersal, disease transmission rate and inter-individual contact distance for transmission, on the spread and persistence of DFTD from local to regional scales. Disease spread, and the ensuing population declines, are synergistically determined by individuals’ dispersal, disease transmission rate and within-population mixing. Transmission rates can be magnified by high dispersal and inter-individual transmission distance. The isolation of local populations effectively reduced metapopulation-level disease prevalence but caused severe declines in metapopulation size and genetic diversity. The relative position of managed (i.e., isolated) local populations had a significant effect on disease prevalence, highlighting the importance of considering metapopulation structure when implementing metapopulation-scale disease control measures. Our findings suggest that population isolation is not an ideal management method for preventing disease spread in species inhabiting already fragmented landscapes, where genetic diversity and extinction risk are already a concern.

Behavioural responses to con- and heterospecific alarm cues by an alien and a coexisting native fish

The monkey goby Neogobius fluviatilis is an invasive Ponto-Caspian fish that enters habitats of the native gudgeon Gobio gobio in European freshwaters, likely belonging to the same prey guild. Their abilities to detect and avoid predation have been poorly understood, although these traits may contribute to the competitive advantage and drive the invasion success of the goby. We tested intra- and interspecific responses of fish from sympatric populations to damage-released alarm cues (skin extract) in laboratory. Both species of fish responded to conspecific and heterospecific cues, but their responses to conspecifics were more diverse (changed social distancing among individuals, reduced vertical and horizontal movement) than those elicited by heterospecifics (changed social distancing only). Moreover, the fish differed in their anti-predation behaviour: the gudgeon increased whilst the monkey goby decreased inter-individual distances and only the gudgeon exhibited thigmotaxis and reduced mobility in response to the conspecific cues. Interspecific differences show that the species exhibit distant anti-predation strategies. This might be associated with their phylogenetic distance and/or higher differentiation of their ecological niches than commonly assumed. Besides, our results suggest that alien species be included in the interspecific exchange of information in local fish assemblages.

Behavioural synchronization in a multilevel society of feral horses.

Behavioural synchrony among individuals is essential for group-living organisms. The functioning of synchronization in a multilevel society, which is a nested assemblage of multiple social levels between many individuals, remains largely unknown. The aim of the present study was to build a model that explained the synchronization of activity in a multilevel society of feral horses. Multi-agent-based models were used based on four hypotheses: A) horses do not synchronize, B) horses synchronize with any individual in any unit, C) horses synchronize only within units, and D) horses synchronize across and within units, but internal synchronization is stronger. The empirical data obtained from drone observations best supported hypothesis D. This result suggests that animals in a multilevel society coordinate with other conspecifics not only within a unit but also at an inter-unit level. In this case, inter-individual distances are much longer than those in most previous models which only considered local interaction within a few body lengths.

A Sliding Window Approach to Investigate the Role of Donor-Recipient Interindividual Genetic Distance on Kidney Transplant Outcome

A Sliding Window Approach to Investigate the Role of Donor-Recipient Interindividual Genetic Distance on Kidney Transplant Outcome

Keep calm and carry on: reactive indifference to predator encounters by a gregarious prey species

Strategies that mitigate predation, whether proactive or reactive, can nevertheless impose significant ‘nonconsumptive’ costs on prey species. Here we used data from two wild vervet monkey, Chlorocebus pygerythru,s groups to assess whether the detection of predators affected their subsequent behaviour to the detriment of their short-term foraging effort. Encounters with the three predator classes present at our study site were frequent and there was evidence that animals were more likely to shift to predator-focused vigilance, which was modulated by alarm call intensity, but not predator type, in the hour following detection. Nevertheless, and against expectation, there was no detectable shift in overall levels of vigilance, which remained low, interindividual distances, travel bearing and, consequently, effort put into foraging. We consider this surprising imperturbability by our study groups in the context of population group size, as our groups are large and have correspondingly lower levels of individual vigilance, as well as in terms of the constraints imposed by small, overlapping territories and frequent predator encounters. Finally, we advocate for increased consideration of the responses of the predators themselves to detection by their prey. • We observed vervet monkeys to assess whether predators affect vigilance and foraging. • Vervets were as likely to forage after predator encounters as they were before. • While female vervets were more vigilant, both sexes were generally unperturbed. • Predator type did not affect the likelihood of vigilance. • We explain this surprising indifference to predators in terms of large group size.

Effects of fasting on collective movement and fission-fusion dynamics in both homogeneous and heterogeneous shoals of a group-living cyprinid fish species.

The present study aimed to reveal the effect of fasting (21 days) on collective movement and interaction dynamics in both homogeneous (eight members fed a commercial diet or deprived of food) and heterogeneous (four fed + four starved members) shoals of juvenile qingbo (Spinibarbus sinensis). The authors of this study measured the shoaling behaviour in both a commonly used rectangular open arena with no spatial complexity and a radial arm maze. When measured in the open arena, the starved shoals had a faster swimming speed and acceleration rate and a longer interindividual distance than the fed shoals, possibly because of the elevated foraging motivation. Nonetheless, the values of the heterogeneous groups were similar to those of the fed groups. Furthermore, in contrast to the fish in homogeneous shoals, the starved fish in heterogeneous shoals showed a slower acceleration rate and speed than fed members in heterogeneous shoals. These results, combined with the relationships of variables at the among- and within-shoal levels, suggested that starved fish limited their motion in heterogeneous shoals to maintain group cohesion but that the fed fish contributed more to maintaining shoal structure, possibly because of the higher energy expenditure required for movement changes. When monitored in a radial arm maze, starved shoals showed more fission-fusion episodes without sacrificing group cohesion, as they adaptively adjusted the frequency and duration of each majority choice. The among-shoal variation revealed that the heterogeneous groups showed less variation in the open arena but more variation in the radius maze than did the homogeneous groups. This difference might arise because dominant members have opposite effects on shoal behaviour and consensus decisions. In conclusion, the present study showed opposite effects of feeding states on collective behaviour between homogeneous and heterogeneous shoals, possibly because of the complicated interactions among members with different energy storage levels and foraging motivations. Furthermore, the heterogeneous groups showed a difference between shoal behaviour in the open area and exploration in the radial arm maze. Future studies manipulating the personality composition of starved and fed members of heterogeneous groups might yield interesting results.

Activity synchrony and travel direction synchrony in wild female Japanese macaques

The degree of behavioural synchrony of animals within a group can be considered a reflection of how individuals adjust their behaviours to manage the costs/benefits accompanying group-living. In this study, we focused on activity synchrony and travel direction synchrony as behavioural synchrony. We aimed to quantify the degree of behavioural synchrony and identify which factors can affect the synchrony in wild females of Japanese macaques. Japanese macaques live in female philopatric multi-female and multi-male groups and have a linear dominance hierarchy. The groups are characterized by changing spatio-temporal cohesiveness among group members. Two observers conducted simultaneous focal animal sampling on adult females using global positioning system devices to record locations. The overall degree of activity synchrony was positive compared with random, and the degree was highest when macaques were located within visual range of each other. Both activity synchrony and travel direction synchrony were influenced by spatial cohesion, i.e. interindividual distance, which shows that the probabilities of synchrony were higher with individuals located closer. Activity synchrony was also influenced by activity type, showing that the probabilities of synchrony were higher when individuals engaged in foraging. These results suggest that synchronized foraging may be caused by enhanced feeding with other group members when they are closer to each other. Our approach to quantitatively measure spatial dispersal while observing group members simultaneously revealed the roles of spatial cohesion and activity types for determining the degree of behavioural synchrony.

Determination of static space requirements for finishing bulls based on image analysis

AbstractIn Europe, conventional housing systems for finishing bulls (Bos taurus) tend to consist of group pens with a high stocking density. Up until now there have been no regulations in place defining bulls’ space requirements, even although insufficient space allowance is considered to impair animal welfare. Our study aimed to measure the surface area that finishing bulls occupy in standing and lying positions. We observed 46 bulls on a German fattening farm. The animals from one pen were assigned to one of three weight classes (W1: &lt; 450 kg; W2:450-649 kg; W3: ≥ 650 kg), and two pens of each weight class were examined. For image recordings, a camera trap was installed above the pens. To analyse the covered surface, the recorded images (n = 242) were edited. Furthermore, the observed lying postures were differentiated in terms of lying position and stretched-out legs. On average, the areas covered by the bulls increased with class of bodyweight. A finishing bull covered up to 1.21 m2 in a standing position and up to 1.57 m2 in a lying position, the most space being needed in an outstretched position. The calculated values provide information only about the surface a finishing bull covered in different positions in the pen. In practice, additional dynamic and social space must be taken into account for recommendations on space requirements, in order to ensure adequate inter-individual distances, social interaction and characteristic behaviours to improve animal welfare.

Environmental habituation and sexual composition affect juveniles' shoaling activity in a cichlid fish (Pelvicachromis taeniatus).

Group living is widespread in animals, and many fishes form shoals. Examining within-group interactions in fishes may contribute to the general understanding of dynamic social structures in animals. The sex ratio of a group has been shown to influence grouping decisions of fishes and can be expected to affect behaviour at group level. Behavioural experiments usually involve relatively short acclimatisation times, although the establishment of environmental habituation in fishes is understudied. This study tests whether the sex ratio and long-term habituation to experimental conditions influence general shoal performance (activity parameters, density) and responses of shoals to an acoustic-mechanical disturbance cue in juveniles of the cichlid fish Pelvicachromis taeniatus via individual tracking. The disturbance consisted of a defined hit against the experimental tank, which caused sudden noise and water movement. We found that a higher proportion of females increases shoal activity (swimming speed and distance covered), suggesting that female P. taeniatus are more active than males. Furthermore, shoal activity declined when shoals habituated to the experimental settings and with the time that the shoals were grouped together, which may reflect intensified group member familiarity. Moreover, behavioural changes after disturbance were weaker when individuals were kept with their group longer and more familiar to the experimental conditions. For prey species, lower activity might be beneficial under natural conditions due to lower conspicuousness of the group. We did not find any significant effects of the investigated factors on shoal density (mean interindividual distance) and speed synchronisation. The results indicate that sexual composition, familiarity between shoal members and habituation to the experimental environment affect shoal performance in a cichlid fish.

Degree of Frugivory Predicts Rates of Food-Related Agonism and Intragroup Proximity in Wild Gray Woolly Monkeys (Lagothrix lagotricha cana).

The main factors influencing feeding competition among members of diurnal primate groups are the distribution, availability, and quality of food resources. Socioecological models predict that temporal availability of preferred resources, such as fruit, can influence intragroup feeding competition, which is expected to affect rates of agonism and intragroup spatial patterns. We evaluated the effects of temporal variation in fruit availability on the degree of frugivory (i.e., the proportion of time spent feeding on fruit in relation to total food consumption) and the effects of fruit availability and degree of frugivory on rates of agonistic interactions, and intragroup proximity in two wild groups of gray woolly monkeys (Lagothrix lagotricha cana) in southwestern Brazilian Amazonia. We recorded 227 agonistic interactions via the all occurrences method and 3549 records of spacing via scan sampling during an 8-mo field study from March to October 2017. We found that fruit availability showed a positive relationship with the woolly monkeys’ degree of frugivory, which in turn showed a positive relationship with the rates of agonism. We also found that degree of frugivory positively affected intragroup proximity in periods of lower fruit availability, and that agonistic interactions and proximity covaried positively. Conversely, as the degree of frugivory increased, monkeys exhibited greater interindividual distances and, consequently, lower rates of agonism, consistent with lower levels of feeding competition in periods of higher fruit availability. Therefore, we suggest that intragroup contest competition for fruits is an important cost of group living even for generalized, opportunistic frugivorous primates, such as woolly monkeys.

The Tim3-galectin-9 interactions in the tumor microenvironment of nasopharyngeal cancer.

2629 Background: The complex cell interactions within the tumor microenvironment (TME) have become a crucial point in cancer research. Yet, the cell interactions might not only depend on the frequency of immune cells, but also on the inter-individual distances as cells might interact via soluble factors and/or cell-cell contact. Accordingly, the mapping of TME has recently gained importance. The aim of this study is to investigate the alternations between galectin-9 (G9) and its natural immunosuppressive receptor, T cell immunoglobulin and mucin domain 3 (Tim3) in nasopharyngeal cancer (NPC). Methods: Using multiplexed quantitative immunofluorescence, we measured the levels of G9 and Tim3 in 95 NPC patients cancerous and 8 normal specimens in tissue microarray format. Cell densities and cell-to-cell distances were quantified. The interaction between G9-expressing tumor cell lines and T cells were also studied. Results: G9-expressing tumor cells were detected in all NPC cases and were significantly higher than normal tissue. Elevated G9 was associated with shorter overall survival (OS: 89% vs 70.5% at 7 years, p: 0.019). Incremental percentages of Tim3+ cells were shown in top 10% cases strongly positive for G9-expressing tumor cells. The number of Tim3+ cells was calculated at 15µm intervals from the nearest G9-expressing tumor cells, of which a significant difference of Tim3+ cells was observed at the 0-15µm distance from G9-expressing cell in cancerous compared to normal tissues. Epithelial short distances were associated with a unfavourable prognosis. Observed short distance were hypothesized to represent Tim3+ cells actively interacting with G9-expressing tumor cells. Accordingly, In vitro cocultured of G9-ovexpressing NPC cell lines induced Tim3 expression on T cells which suppressed the T-cell mediate cytotoxicity on tumor cells. Conclusions: Our findings indicate a specific preexisting profile of Tim3+ and G9-expressing tumor cells and demonstrated that Tim3+ cells were mainly found intratumorally within 15µm of a NPC cell. The relevance of Tim3+ and G9+ distances reflect a potential marker of their functional interaction. Our results could have important implications for clinical therapeutic strategies. Since high G9 expression have poorer OS, they would deserve a different therapeutic strategy.[Table: see text]

Hydrodynamical effect of parallelly swimming fish using computational fluid dynamics method.

Fish form schools because of many possible reasons. However, the hydrodynamic mechanism whereby the energy efficiency of fish schools is improved still remains unclear. There are limited examples of fish models based on actual swimming movements using simulation, and the movements in existing models are simple. Therefore, in this study, we analyzed the swimming behavior of Biwa salmon (Oncorhynchus sp., a salmonid fish) using image analyses and formulated its swimming motion. Moreover, computational fluid dynamics analysis was carried out using the formulated swimming motion to determine the fluid force acting on the fish body model with real fish swimming motion. The swimming efficiency of the fish model under parallel swimming was obtained from the calculated surrounding fluid force and compared for different neighboring distances. The flow field around the fish model was also examined. The swimming efficiency of two fish models swimming parallelly was improved by approximately 10% when they were separated by a distance of 0.4L, where L is the total length of the model. In addition, the flow field behind the fish body was examined under both inphase and antiphase conditions and at inter-individual distances of 0.8L and 1.2L. The apparent flow speed in the distance range of 0.5-2.0L from the midpoint of the snouts of the two individuals was lower than the swimming speed. The pressure distribution on the fish model showed an elevated pressure at the caudal fin. Interestingly, we obtained an isopleth map similar to that of a caudal peduncle. To avoid a negative thrust, the aft part of the body must be thin, as shown in the isopleth map obtained in this study.

Shoaling, boldness, anxiety-like behavior and locomotion in zebrafish (Danio rerio) are altered by acute benzo[a]pyrene exposure

Environmental exposure to crude oil and/or its derivatives in fishes can negatively impact survival, morphology and physiology, but relatively little focus has been on behavior. Exposures can influence prey-predator interactions, courtship and other vital behaviors, leading to individual or population disruption at toxicant levels well below those producing morphological or physiological changes. The few behavioral studies of polycyclic aromatic hydrocarbons (PAHs) on fish behavior have yielded highly inconsistent results, likely relating to chronic vs. acute treatment. A few studies report lethargy and decreased exploratory behavior, while others indicate increased anxiety and greater exploratory behavior with PAH exposure. In our study on zebrafish (Danio rerio), we hypothesized that even relatively brief (30 min) exposure to the PAH benzo[a]pyrene (B[a]P) would impact group shoaling and individual behaviors in open field and novel object exploration tests. Exposures comprised measured concentrations of 1.0 μM, 10 μM, or 100 μM, B[a]P. Compared to controls, inter-individual distance (IID) was significantly increased by 100 μM B[a]P, but not by 1.0 μM or 10 μM B[a]P. Total distance moved by shoals was decreased significantly at B[a]P concentrations of 1.0 μM, 10 μM and 100 μM. In the open field test of individual locomotion and anxiety-like behavior, time spent in the thigmotaxis zone along the walls of the circular test arena (a proxy for anxiety-like behavior), was decreased at 100 μM. In the novel object approach test to investigate boldness, time spent near the object was significantly increased by both 10 μM and 100 μM B[a]P. Collectively, these data indicate a complex suite of changes in zebrafish including altered shoal dynamics, decreased anxiety, increased boldness, and decreased locomotion associated with exposure to B[a]P.