Predatory fish select for coordinated collective motion in virtual prey

Movement in animal groups is highly varied and ranges from seemingly disordered motion in swarms to coordinated aligned motion in flocks and schools. These social interactions are often thought to reduce risk from predators, despite a lack of direct evidence. We investigated risk-related selection for collective motion by allowing real predators (bluegill sunfish) to hunt mobile virtual prey. By fusing simulated and real animal behavior, we isolated predator effects while controlling for confounding factors. Prey with a tendency to be attracted toward, and to align direction of travel with, near neighbors tended to form mobile coordinated groups and were rarely attacked. These results demonstrate that collective motion could evolve as a response to predation, without prey being able to detect and respond to predators.     

双尾新小绥螨种群取食猎物偏好性

[目的]研究添加人工饲料后不同食料饲养的双尾新小绥螨实验室种群对不同猎物的取食影响,分析人工饲料在双尾新小绥螨实验室种群扩繁和释放中的作用.[方法]采用小室法观察在有无人工饲料条件下,自然猎物、替代猎物和人工饲料饲养的双尾新小绥螨种群对目标猎物的捕食选择性和取食量差异,采用偏好性系数理论公式和影响系数,分析人工饲料与猎...     

Cascading effects of the loss of apex predatory sharks from a coastal ocean

Impacts of chronic overfishing are evident in population depletions worldwide, yet indirect ecosystem effects induced by predator removal from oceanic food webs remain unpredictable. As abundances of all 11 great sharks that consume other elasmobranchs (rays, skates, and small sharks) fell over the past 35 years, 12 of 14 of these prey species increased in coastal northwest Atlantic ecosystems. Effects of this community restructuring have cascaded downward from the cownose ray, whose enhanced predation on its bay scallop prey was sufficient to terminate a century-long scallop fishery. Analogous top-down effects may be a predictable consequence of eliminating entire functional groups of predators.     

饵料鱼大小对乌鳢捕食的影响

测量了乌鳢口裂形态,以泥鳅(Misgurnus anguillicaudatus)作为饵料鱼,估算了不同规格乌鳢的摄食率,研究了饵料鱼大小对乌鳢捕食的影响.乌鳢口宽(M_w,cm)、口高(M_H,cm)和口面积(M_A,cm~2)与其全长(T_L,cm)的回归方程分别为:M_W=1.65~(e0.0242TL);MH=1.64 ~(e0.022TL);MA=2.12e~(0.0465TL).当水温保持在22～23℃时,4个规格组的乌鳢对泥鳅的摄食率无显著的差别(ANOVA,P>0.05),均值为1.68%.乌鳢对泥鳅的捕食具有明显的大小选择性,乌鳢最喜欢捕食猎物/捕食者大小比为0.25的泥鳅,很少捕食或不捕食猎物/捕食者大小比小于0.06或大于0.45的泥鳅.     

圆果大赤螨对茶红蜘蛛的捕食作用

圆果大赤螨对茶红蜘蛛捕食作用的拟合方程符合Holling圆盘方程Ⅱ型,功能反应受到猎物虫态、温度和捕食者密度的影响.圆果大赤螨成螨显著地趋向于取食茶红蜘蛛的幼螨和若螨,日均最高捕食量分别达49.31和38.65头,对卵和成螨的选择性较差.在相同猎物密度条件下,温度为15-30℃时,捕食数量随着温度的升高而增加;温度为(35±1)℃时捕食数量随着温度的升高而减少.温度为(30±1)℃时,捕食数量最大,这一温度与茶红蜘蛛秋季高峰期的温度相吻合.圆果大赤螨在捕食时存在种内干扰反应,随着捕食者密度的增大,日均捕食量逐渐减少,捕食作用也相应减弱,干扰系数m为0.7589,搜索常数Q为0.9983,E=0.9983P-0.7589.     

Predation risk affects reproductive physiology and demography of elk

Elk (Cervus elaphus) in the Greater Yellowstone Ecosystem alter patterns of aggregation, habitat selection, vigilance, and foraging in the presence of wolves (Canis lupus). Antipredator behaviors like these can reduce predation risk but are also likely to carry costs. Data from five elk populations studied for 16 site years showed that progesterone concentrations (from 1489 fecal samples) declined with the ratio of elk to wolves. In turn, progesterone concentrations were a good predictor of calf recruitment in the subsequent year. Together, these data suggest that wolves indirectly affect the reproductive physiology and the demography of elk through the costs of antipredator behavior.     

Nocturnal aerial predation of fireflies by light-seeking fireflies

Female Photuris fireflies guided by their prey's luminescence attack flying fireflies at night. They sometimes use this hunting tactic together with prey attraction by mating-signal mimicry. Such predation could have been a major factor in the evolution of signaling behavior of American fireflies. Nocturnal aerial predation by an insect and attack guidance on energy emitted by airborne prey have not previously been reported.     

剑毛帕厉螨与黔下盾螨种间相残的研究

【目的】研究食用菌害虫2种天敌剑毛帕厉螨(Stratiolaelaps scimitus)和黔下盾螨(Hyposipis chianensis)的种间相残特性,为开展两者的协调应用提供理论依据。【方法】在有或无自然猎物(腐食酪螨Tyrophagus putrescentiae)条件下,观察2种捕食螨不同螨态间的相残程度及相残后若螨的发育和雌成螨的产卵量。【结果】有自然猎物腐食酪螨时,2种螨较少发生相残。无自然猎物时,2种螨发生相残,相残程度与捕食者螨态和猎物螨态密切相关,但黔下盾螨若螨不捕食剑毛帕厉螨幼螨。捕食黔下盾螨卵或幼螨的剑毛帕厉螨若螨80%和100%发育到成螨,若螨期分别为7.88d和7.30d;捕食剑毛帕厉螨卵的黔下盾螨若螨仅有30%发育至成螨;缺乏自然猎物时,2种捕食螨相残后雌成螨的产卵量均显著低于存在腐食酪螨时的产卵量,一种捕食螨仅通过捕食另一种捕食螨,无法维持种群正常增长速度。【结论】剑毛帕厉螨与黔下盾螨不适合作为相互的猎物,存在其它更为适合的猎物时,不优先选择相残,在害虫密度较大的条件下可以同时应用。     

Primate predation: interim report on the development of a tradition in a troop of olive baboons

A troop of olive baboons, Papio anubis, has developed systematic predation, which includes hunting and sharing of meat. Although meat-eating among nonhuman primates-baboons and chimpanzees especially-had been discovered in earlier field studies, systematic predation had been reported for chimpanzees and humans only. Starting as an adult male activity in the olive baboon troop, this tradition rapidly expanded to include capture and consumption of prey by adult females and juveniles of all ages and both sexes. Infants eat but have not been observed to capture prey.     

Signal perception in frogs and bats and the evolution of mating signals

Psychophysics measures the relationship between a stimulus's physical magnitude and its perceived magnitude. Because decisions are based on perception of stimuli, this relationship is critical to understanding decision-making. We tested whether psychophysical laws explain how female túngara frogs (Physalaemus pustulosus) and frog-eating bats (Trachops cirrhosus) compare male frog calls, and how this imposes selection on call evolution. Although both frogs and bats prefer more elaborate calls, they are less selective as call elaboration increases, because preference is based on stimulus ratios. Thus, as call elaboration increases, both relative attractiveness and relative predation risk decrease because of how receivers perceive and compare stimuli. Our data show that female cognition can limit the evolution of sexual signal elaboration.     

Predators accelerate nutrient cycling in a bromeliad ecosystem

Conventional ecological theory predicts that predators affect nutrient cycling by decreasing the abundance or activity of prey. By using a predator-detritivore-detritus food chain in bromeliads, we show that predators can increase nutrient cycling by a previously undescribed, but broadly applicable, mechanism: reducing nutrient export by prey emigration. Contrary to expectations, predation on detritivores increases detrital nitrogen uptake by bromeliads. Predation reduces detritivore emergence and hence export of nitrogen from the system. Detritivores therefore benefit their host plant, but only when predators are present. More generally, our results show that predator loss or extinction can dramatically and unexpectedly affect ecosystem functioning.     

食螨瓢虫(Stethorus sp.)对啤酒花害螨的控制作用

本文利用回归最优设计方法探讨了食螨瓢虫(Stethorus sp.)对啤酒花害螨—土耳其斯坦叶螨 Tetranychus turkeslani 的控制作用。回归最优设计适合捕食者—猎物系统相互关系的研究,能够揭示猎物密度、捕食者密度对捕食作用的影响。食螨瓢虫成虫每日可捕食成螨28～30头或捕食幼若螨40～50头。一头食螨瓢虫成虫一生累计可捕食成螨1700多头或幼若螨2750头。田间自然控制效果表明,食螨瓢虫可有效地控制啤酒花害螨种群的增长,控制效果可达87%以上。由于食螨瓢虫的自然控制作用,使得用药时间推迟30d 左右,农药成本减少71.4%,提高了啤酒花的产量和品质,利用食螨瓢虫控制叶螨,可以获得良好的经济、生态、社会效益。     

Bushmeat hunting, wildlife declines, and fish supply in West Africa

The multibillion-dollar trade in bushmeat is among the most immediate threats to the persistence of tropical vertebrates, but our understanding of its underlying drivers and effects on human welfare is limited by a lack of empirical data. We used 30 years of data from Ghana to link mammal declines to the bushmeat trade and to spatial and temporal changes in the availability of fish. We show that years of poor fish supply coincided with increased hunting in nature reserves and sharp declines in biomass of 41 wildlife species. Local market data provide evidence of a direct link between fish supply and subsequent bushmeat demand in villages and show bushmeat's role as a dietary staple in the region. Our results emphasize the urgent need to develop cheap protein alternatives to bushmeat and to improve fisheries management by foreign and domestic fleets to avert extinctions of tropical wildlife.     

星豹蛛(Pardosa astrigera L. Koch)对菜蚜的捕食作用及模拟模型的研究

研究了星豹蛛对菜蚜的日捕食量、捕食功能反应, 构建了捕食模拟模型。室内测定结果表明, 星豹蛛成蛛与亚成蛛对成熟菜蚜的日捕食量上限为42头/天, 对该虫的捕食量随猎物密度的增加而增加, 随自身密度的增加而减少。用Holling圆盘方程进行模拟, 其功能反应属于HollingⅡ型; 对自身密度的功能反应可以用Hassell-Varley提出的方程进行拟和。星豹蛛对自身密度与猎物密度的联合反应方程已被构建。经卡方检验, 以上各方程理论值与实际值误差均不显著。     

African wild ungulates compete with or facilitate cattle depending on season

Savannas worldwide are vital for both socioeconomic and biodiversity values. In these ecosystems, management decisions are based on the perception that wildlife and livestock compete for food, yet there are virtually no experimental data to support this assumption. We examined the effects of wild African ungulates on cattle performance, food intake, and diet quality. Wild ungulates depressed cattle food intake and performance during the dry season (competition) but enhanced cattle diet quality and performance during the wet season (facilitation). These results extend our understanding of the context-dependent-competition-facilitation balance, in general, and are critical for better understanding and managing wildlife-livestock coexistence in human-occupied savanna landscapes.     

转基因食品感知风险对消费者购买意愿的影响研究——基于武汉市消费者的调查分析

消费者对转基因食品(Genetically Modified Foods,GMF)的感知风险及购买意愿不仅事关政府和企业的相关决策,而且事关转基因食品的可持续发展。本研究基于武汉市384名消费者的调查数据,通过因子分析和回归分析的二步模型,对消费者的GMF感知风险及其对购买意愿的影响进行实证分析。研究表明,消费者对GMF的感知风险主要集中在4个方面,即:人体健康风险、社会经济风险、生态环境风险和食品功能风险。其中,前三者显著影响消费者对GMF的购买意愿,食品功能感知风险对GMF购买意愿的影响并不显著。     

新疆荒漠林人工招引猛禽防治鼠害研究

采用设立栖架和人工巢箱等措施招引猛禽防治荒漠林鼠害.阜康市荒漠林防治区设立栖架后,红隼(Falco tinnunculus)和棕尾 (Buteo rufinus)的遇见率均有大幅提高,分别是对照区的6倍和11倍.精河县伊里生火车站荒漠林防治区在常规化学防治后继续采用天敌招引措施以及新疆甘家湖梭梭自然保护区防治区直接采用天敌招引措施后,4年内防治区的鼠密度一直处于低水平,基本无鼠害.认为设立栖架和人工巢箱可以提高猛禽的遇见率并对低密度水平下的害鼠有长期控制作用.     

赛罕乌拉自然保护区西伯利亚狍的家域动态分析

【目的】了解在自然保护区相对隔离环境中西伯利亚狍家域的季节和年度动态,分析狍对微生境和捕食风险的适应,为促进种群恢复和栖息地保护提供依据。【方法】在内蒙古赛罕乌拉国家级自然保护区使用无线电遥测技术,以三角形法则进行个体定位,利用最小凸多边形法计算家域面积。【结果】本次研究共捕捉到8只西伯利亚狍,其中3只以红外相机影像确认被猞猁捕食,面临较高的捕食风险。狍的年度和季节家域面积存在差异,春季的家域显著大于其他3个季节,同时,活动范围在冬季有从较高海拔山坡向沟底迁移的趋势。繁殖期与非繁殖期、亚成体与成体家域面积也存在差异。个体年度家域存在重叠,显示核心家域较为稳定。【结论】影响西伯利亚狍个体家域年度和季节变化的因素为觅食机会、捕食风险和能量需求。据此提出了补加营养盐和越冬饲料的管理对策,促进保护区狍种群的复壮。     

Predation in the paleozoic: gastropod-like drillholes in devonian brachiopods

Middle Devonian articulate brachiopods (Ludlowville and Moscow Formations, Hamilton Group, New York) have external tapered holes with a central boss that are indistinguishable from drillholes of naticid gastropods that are known from the Triassic and later. Drillholes are specific to prey (ribbed shells were avoided) and specific to sites on prey. Healed drillholes suggest penetration of live prey. As many as 44 percent of the preferred prey are drilled, indicating a level of predation that has been reported only from post-Paleozoic strata.     

消费者对国产婴幼儿奶粉质量安全风险感知偏差及其影响因素

为了解和调整消费者对国产婴幼儿奶粉质量安全风险感知偏差,基于情景模拟实验法获取559位消费者数据,采用有序Logistic模型,对消费者的国产婴幼儿奶粉质量安全风险感知偏差及其影响因素展开实证研究.结果表明:1)89.98％的消费者主观感知到的国产婴幼儿奶粉质量安全风险高于客观风险水平,存在风险感知偏差.2)产品知识、...