Parasitoid secretions provoke ant warfare

Insect social parasites are extreme specialists that typically use mimicry or stealth to enter ant colonies to exploit the rich, but fiercely protected, resources within their nests. Here we show how a parasitic wasp (parasitoid) contrives to reach its host, itself an endangered species of social parasite that lives inside the brood chambers of ant nests, by releasing semiochemicals to induce in-fighting between worker ants, locking the colony in combat and leaving it underprotected. Four of these chemicals are new to biology and have the potential to control pest species by inducing different agonistic behaviours in ants.     

二种植绥螨对朱砂叶螨利他素定位反应的比较

利用嗅觉仪测定智利小植绥螨和拟长钝绥螨对其猎物朱砂叶螨所释放的利他素的定向行为并作了比较研究，阐明了与这二种植绥螨的定位反应有关的刺激源是除雄螨以外不同发育阶段的叶螨及其分泌物和排泄物，而与叶螨的寄主植物无关，不同植绥螨对同一种叶螨不同发育阶段产生的利他素源反应有着一定的种间特异性。     

基于深度强化学习与流固耦合技术的鱼类自主游动行为模拟

鱼类自主游动的模拟问题一直是仿生学、鱼类行为学以及生态水力学等诸多学科共同关注的重要难题。建立一种基于流固耦合数值模拟技术与深度强化学习算法的智慧鱼体自主行为决策平台,可以实现鱼体在不同周围环境条件下以最优决策方案完成游泳任务。该平台采用深度强化学习算法实现鱼脑功能,模拟其不断学习和最终决策;通过浸没边界-Lattice Boltzmann方法对流场及鱼体运动进行实时模拟,可为鱼体提供丰富的训练样本并执行鱼脑决策。基于该平台对鱼类典型捕食运动以及卡门游动进行训练并分析其训练效果。仿真结果表明：在捕食游动问题中,具有不同初始位置偏角的鱼体均能以最优轨迹到达目标点;在卡门游动问题中,鱼体能自主调节尾拍频率,使之接近涡街脱落频率,进而从卡门涡场中吸收能量,以稳定步态在涡街中运动。在鱼类自主游动问题的研究方面,该决策平台较传统物理实验具有更强大的复杂流场适应性,并可为水利工程、生态环境工程等领域的数字孪生提供技术支持。     

多物流配送中心选址及求解

经典蚁群算法不能直接用于求解多配送中心选址问题(MDLP),据此,将MDLP映射为扩展K-TSP过程并设计了改进的蚁群算法.改变了经典蚁群算法禁忌表的设置方式,算法运行时,给蚁群建立一个共享禁忌表,里面存放所有蚂蚁访问过的客户点,任何蚂蚁只能选择共享禁忌表未曾记录的客户点,从而增强蚂蚁间的信息交流,促进它们的分工与协作,使蚂蚁无遗漏无重复地遍历各配送点并找出问题的最优解.为提高算法的求解性能,在蚂蚁的选择规则里加入了代价引导函数,使用2-opt策略优化可行解并优化了信息素的更新方式.仿真算例及算法对比表明,模型和算法可以有效地表达和求解MDLP.     

实验平台装置边缘影响和蚁群聚集程度研究

为深入研究自组织聚集的微观机制, 采用日本弓背蚁作实验材料, 在二维正方形平面和二维圆形平面实验台上进行蚁群实验, 通过高速摄像机视频跟踪并进行定量统计分析. 实验结果表明, 实验装置边缘对蚂蚁有“吸引”作用, 随着群体规模增加, 装置边缘对蚁群吸引减弱. 通过研究蚂蚁速度, 发现因为装置边缘的吸引, 蚂蚁在边界和非边界运动状态不同. 在边界, 蚂蚁主要状态是“停止”和“低速运动”; 在非边界, 蚂蚁主要状态是“低速运动”. 本文首次提出用层次社会熵定量测量蚁群聚集程度, 发现其随着蚁群群体规模增加呈现先上升后下降趋势, 表明蚁群聚集程度随着蚁群群体规模增加先下降后上升.      

贵州疣螈捕食和反捕行为的初步观察

采用野外调查与室内饲养观察相结合的方法,对我国云贵高原特有种贵州疣螈（Ｔｙ ｌｏｔｏｔｒｉｔｏｎｋｗｅｉｃｈｏｗｅｎｓｉｓ）的捕食行为和反捕行为进行了初步观察。记录了贵州疣螈常见的捕食行为和反捕行为。贵州疣螈的捕食行为基本上是一种被动式的捕食方式,捕食过程中嗅觉起了主要作用,捕食动作迅猛而准确;幼体时期存在相互残食现象。反捕行为基本上是一种防御行为,利用其自身良好的保护色和逃逸作为反捕手段,在其被捕捉后,又利用嘴、尾等攻击敌人,同时还利用体表分泌的一种有特殊臭味的粘液来作为御敌手段。     

一类捕食与被捕食系统的持续生存性与周期解

讨论了一类一个捕食者种群和两个食饵种群构成的非自治生态系统．系统中食饵种群有各自的避难所，它们在避难所内外可以迁移．应用常微分方程定性和稳定性的方法，得到了在一定条件下系统是持续生存的；进一步，若系统是一个周期系统，则在合适的条件下，系统存在唯一的、全局渐近稳定的周期解     

Trail geometry gives polarity to ant foraging networks

Pheromone trails are used by many ants to guide foragers between nest and food. But how does a forager that has become displaced from a trail know which way to go on rejoining the trail? A laden forager, for example, should walk towards the nest. Polarized trails would enable ants to choose the appropriate direction, thereby saving time and reducing predation risk. However, previous research has found no evidence that ants can detect polarity from the pheromone trail alone. Pharaoh's ants (Monomorium pharaonis) produce elaborate trail networks throughout their foraging environment. Here we show that by using information from the geometry of trail bifurcations within this network, foragers joining a trail can adaptively reorientate themselves if they initially walk in the wrong direction. The frequency of correct reorientations is maximized when the trail bifurcation angle is approximately 60 degrees, as found in natural networks. These are the first data to demonstrate how ant trails can themselves provide polarity information. They also demonstrate previously unsuspected sophistication in the organization and information content of networks in insect societies.     

Mass march of termites into the deadly trap.

Carnivorous pitcher plants of the genus Nepenthes are not usually very selective about their prey, catching anything that is careless enough to walk on their slippery peristome, but Nepenthes albomarginata is an exception. We show here that this plant uses a fringe of edible white hairs to lure and then trap its prey, which consists exclusively of termites in enormous numbers. This singular feature accounts for the specialization of N. albomarginata for one prey taxon, unique so far among carnivorous plants.     

The evolution of müllerian mimicry in multispecies communities

Prey species that are unprofitable to attack often share conspicuous colours and patterns with other coexisting defended species. This phenomenon, termed müllerian mimicry, has long been explained as a consequence of selection on defended prey to adopt a common way of advertising their unprofitability. However, studies using two unpalatable prey types have not always supported this theory. Here we show, using a system of humans hunting for computer-generated prey, that predators do not always generate strong selection for mimicry when there are two unprofitable prey types. By contrast, we demonstrate that when predators are faced with a range of different prey species, selection on unprofitable prey to resemble one another can be intense. Here the primary selective force is not one in which predators evaluate the profitabilities of distinct prey types independently, but one in which predators learn better to avoid unprofitable phenotypes that share traits distinguishing them from profitable prey. This need to simplify decision making readily facilitates the spread of imperfect mimetic forms from rarity, and suggests that müllerian mimicry is more likely to arise in multispecies communities.     

基于DSP的信号与系统仿真实验平台的设计

提出了一种基于DSP的信号与系统仿真实验平台实现方案．这一实验平台采用了将软件和硬件有机结合来进行仿真的方法,当用户在计算机界面上进行实验操作时,实验结果波形可以在实际的示波器上显示出来．仿真实验平台的软件方面主要是编写了一个在主机上运行的用户界面,用以将仿真实验的内容完整地展示给用户,并允许用户进行实验操作．硬件方面则使用一块以DSP系统为核心的实验板与主机通信,主要功能是将用户进行的实验操作进行计算,并将结果通过仿真,在示波器上显示出来．从而使使用者获得较为真实的实验感受,对信号处理有一个更深层次的认识．     

基于Open vSwitch的SDN网络平台构建方法

针对软件定义网络实验环境问题,对SDN网络及其工作原理进行了分析,提出了一种在x86架构上基于Open v Switch的SDN网络平台的构建方法,降低了网络平台搭建的成本,测试了此网络架构下主机间、主机与因特网的连通性.测试结果表明:使用这种方法搭建SDN网络正确有效,为后续研究奠定了基础.     

基于物联网的汉江水环境参数监测系统设计

为实现南水北调中线水源地汉江的水体环境参数智能化监测,研究设计一种基于物联网的汉江水环境参数监测系统。该系统由监测主机和检测终端组成,监测主机通过LoRa无线方式发送采集控制指令到检测终端,检测终端接收指令并实施水温、pH值、浑浊度等水体环境数据采集,并将采集数据通过LoRa无线方式发送给监测主机,由监测主机完成数据分析、显示和异常语音告警,监测主机具有基于NB-IoT的OneNET云平台自动接入与数据上传功能,能将检测数据自动上传到OneNET云平台,管理人员通过手机app登录云平台,即可实现水体环境的远程监测管理功能。实验测试结果表明：本系统各项功能运行较为稳定,监测主机和检测终端的LoRa无线有效通信距离约为1640米,系统设计方案合理可行,能够为南水北调水源地水体环境智能化监测管理提供技术基础和方案参考。     

Predators increase the risk of catastrophic extinction of prey populations.

There has been considerable research on both top-down effects and on disturbances in ecological communities; however, the interaction between the two, when the disturbance is catastrophic, has rarely been examined. Predators may increase the probability of prey extinction resulting from a catastrophic disturbance both by reducing prey population size and by changing ecological traits of prey individuals such as habitat characteristics in a way that increases the vulnerability of prey species to extinction. We show that a major hurricane in the Bahamas led to the extinction of lizard populations on most islands onto which a predator had been experimentally introduced, whereas no populations became extinct on control islands. Before the hurricane, the predator had reduced prey populations to about half of those on control islands. Two months after the hurricane, we found only recently hatched individuals--apparently lizards survived the inundating storm surge only as eggs. On predator-introduction islands, those hatchling populations were a smaller fraction of pre-hurricane populations than on control islands. Egg survival allowed rapid recovery of prey populations to pre-hurricane levels on all control islands but on only a third of predator-introduction islands--the other two-thirds lost their prey populations. Thus climatic disturbance compounded by predation brought prey populations to extinction.     

Asymptotic prey profitability drives star-nosed moles to the foraging speed limit

Foraging theory provides models for predicting predator diet choices assuming natural selection has favoured predators that maximize their rate of energy intake during foraging. Prey profitability (energy gained divided by prey handling time) is an essential variable for estimating the optimal diet. Time constraints of capturing and consuming prey generally result in handling times ranging from minutes to seconds, yet profitability increases dramatically as handling time approaches zero, providing the potential for strong directional selection for increasing predator speed at high encounter rates (tiny increments in speed increase profitability markedly, allowing expanded diets of smaller prey). We provide evidence that the unusual anatomical and behavioural specializations characterizing star-nosed moles resulted from progressively stronger selection for speed, allowing the progressive addition of small prey to their diet. Here we report handling times as short as 120 ms (mean 227 ms) for moles identifying and eating prey. 'Double takes' during prey identification suggest that star-nosed moles have reached the speed limit for processing tactile information. The exceptional speed of star-nosed moles, coupled with unusual specializations for finding and eating tiny prey, provide new support for optimal foraging theory.     

变色沙蜥(Phrynocephalus versicolor)的耐饥能力与食性研究

变色沙蜥于2004年7月采自新疆准噶尔盆地南缘沙漠地区，成体在夏季有较强的耐饥能力，在提供饮水条件下的耐饥能力为45～52d，平均为48.5d，在不提供饮水条件下的耐饥能力为17-24d左右，平均20．3d。以胃内容物分析法研究其食性，结果显示在夏季的食物主要是蚂蚁，占食物总量的84％，其次是步行虫，占11％。     

Biomechanics (Communication arising): prey attack by a large theropod dinosaur

Prey-capture strategies in carnivorous dinosaurs have been inferred from the biomechanical features of their tooth structure, the estimated bite force produced, and their diet. Rayfield et al. have used finite-element analysis (FEA) to investigate such structure-function relationships in Allosaurus fragilis, and have found that the skull was designed to bear more stress than could be generated by simple biting. They conclude that this large theropod dinosaur delivered a chop-and-slash 'hatchet' blow to its prey, which it approached with its mouth wide open before driving its upper tooth row downwards. We argue that this mode of predation is unlikely, and that the FEA results, which relate to an 'overengineered' skull, are better explained by the biomechanical demands of prey capture. Understanding the mechanics of predation is important to our knowledge of the feeding habits of carnivorous dinosaurs and for accurate reconstruction their lifestyles.     

Coexistence of two sympatric and mOrpho1ogically similar bat species Rhinolophus affnis and Rhinolophus pearsoni

Ecologists have long focused on the coexistence of sympatric species.Here,we investigated two horseshoe bat species,Rhinolophus affinis and Rhinolophus pearsoni inhabited in the same cave,for their foraging strategies,niche differentiation,prey selection,and their coexistence status.These two species of horseshoe bats were ditierent in the dominant frequency of their echolocation calls.but similar in their morphology.We found evidence for prey selectivity although there was a high degree of overlap in prey categories and sizes.R affinis and R pearsoni foraged on 16 and 7 categories insects,respectively,with Pyralidae,Geometridae,Melolonthidae dominating their diets.The degree of trophic niche overlap was 0.69.Pairwise comparisons suggested that there was no obvious differentiation in prey categories and size.However,high prey availability in the environment(Simpson diversity index=0.79 and Margalef richness index=4.121 contributed to their coexistence by dampening the interspecific competition.Since there are one or more mechanisms facilitating species coexistence in a community,our results suggest that the spatial niche differentiation in foraging microhabitats and in foraging habitats at landscape scale may promote the coexistence of the two bat species.However,additional field data are needed to confirm this speculation.     

Coexistence of two sympatric and morphologically similar bat species Rhinolophus affinis and Rhinolophus pearsoni

Ecologists have long focused on the coexistence of sympatric species. Here, we investigated two horseshoe bat species, Rhinolophus affinis and Rhinolophus pearsoni inhabited in the same cave, for their foraging strategies, niche differentiation, prey selection, and their coexistence status. These two species of horseshoe bats were different in the dominant frequency of their echolocation calls, but similar in their morphology. We found evidence for prey selectivity although there was a high degree of overlap in prey categories and sizes. R. affinis and R. pearsoni foraged on 16 and 7 categories insects, respectively, with Pyralidae, Geometridae, Melolonthidae dominating their diets. The degree of trophic niche overlap was 0.69. Pairwise comparisons suggested that there was no obvious differentiation in prey categories and size. However, high prey availability in the environment （Simpson diversity index = 0.79 and Margalef richness index = 4.12） contributed to their coexistence by dampening the interspecific competition. Since there are one or more mechanisms facil- itating species coexistence in a community, our results suggest that the spatial niche differentiation in foraging rnicrohabitats and in foraging habitats at landscape scale may promote the coexistence of the two bat species. However, additional field data are needed to confirm this speculation.     

Ant odometry in the third dimension.

Desert ants (Cataglyphis) are renowned for their ability to perform large-scale foraging excursions and then return to the nest by path integration. They do so by integrating courses steered and the distances travelled into a continually updated home vector. Whereas the angular orientation is based on skylight cues, how the ants gauge the distances travelled has remained largely unclear. Furthermore, almost all studies on path integration in Cataglyphis, as well as in spiders, rodents, and humans, have aimed at understanding how the animals compute homebound courses in the horizontal plane. Here, we investigate for the first time how an animal's odometer operates when a path integration task has to be accomplished that includes a vertical component. We trained Cataglyphis ants within arrays of uphill and downhill channels, and later tested them on flat terrain, or vice versa. In all these cases, the ants indicated homing distances that corresponded not to the distances actually travelled but to the ground distances; that is, to the sum of the horizontal projections of the uphill and downhill segments of the ants' paths.