What best explains vigilance in elk: characteristics of prey, predators, or the environment?

We quantified the vigilance levels of elk (Cervus elaphus) preyedon by wolves (Canis lupus) in Yellowstone National Park, betweenJanuary and May in 2005 and 2006, and used Akaike's informationcriterion to compare a set of 38 regression models for vigilancelevels. These models combined up to 9 predictor variables of3 types: characteristics of the prey group (herd size and composition),characteristics of the predator (wolf pack size, distance away,and the presence/absence of a kill), and characteristics ofthe local environment (distance to woodland edges, snow depth,and snow cover). The set of models spanned a range of complexityfrom simple univariate models to complex combinations with upto 3 variables of each type. Complex models incorporating thecharacteristics of the wolf pack, the structure of the elk herd,and the environmental conditions had higher information contentthan simple models. Although univariate models of vigilancedetect significant relationships, they have low informationcontent relative to multivariate models. These results showthat elk assesses factors of several types when assessing riskand deciding how much time to allocate to vigilance. In particular,we found that all well-supported models of vigilance includedseveral "prey" variables and several "predator" variables. Thisresult highlights the need to consider information about predatorswhen trying to explain variation in vigilance levels in prey.     

Pre-retirement predator encounters alter the morning behavior of captive marmosets (Callithrix geoffroyi)

Limited data are available on the long-term effect an encounter with a predator has on its potential prey. Anecdotal reports from field research indicate that even unsuccessful attacks by predators on callitrichids have long-lasting effects. The subjects for this study were two groups of Geoffroy's marmosets (Callithrix geoffroyi) housed outside, off exhibit, at the Center for Reproduction of Endangered Species at the San Diego Wild Animal Park. Before they retired in the evening, the marmosets were observed under one of three conditions: snake model, cloth control, and no-stimulus control. Data were collected the following morning for 1 hr after the animals emerged from the sleeping box. Compared to control conditions, exposure to the snake model before retirement the previous evening was associated with significantly more vigilance checks (i.e., inspecting the area where the stimulus was last seen), and a delay in beginning to forage on the ground. These results suggest that callitrichids use recent threatening experiences to guide their vigilance behavior 12 hr after the threat is detected, and that they adjust their early morning behavior in response to potential predatory threats.     

Intrinsic and Extrinsic Factors Influence Expression of Defensive Behavior in Plains Hog‐Nosed Snakes (Heterodon nasicus)

Animals failing to deter predation are eaten. Among the many deterrents to predation, antipredator behaviors are perhaps the most variable, ranging from active (fight or flight) to passive (immobility). We assessed variation in the expression of a passive defensive behavior, death‐feigning, in Plains Hog‐nosed Snakes (Heterodon nasicus) and predicted that intrinsic and extrinsic factors would influence the duration of this behavior and the latency to its onset. We simulated predatory attacks on 27 snakes encountered in the field, and analyzed the behavioral responses of snakes as a function of differences among individuals (sex and size) and environmental factors (temperature and microhabitat). Larger snakes death‐feigned for longer durations than smaller ones; this relationship was stronger for female snakes than for males. Death feints were initiated sooner when snakes were encountered at higher temperatures. Extrinsic factors had a greater influence on latency to death‐feigning behavior, whereas intrinsic factors more strongly influenced its duration. Because our results involved wild snakes, they provide an improved, highly relevant understanding of individual and environmental factors that regulate the expression of immobile defensive behavior. Furthermore, additional hypotheses can now be proposed that address the evolution of defensive behaviors that leave animals prone to attack.     

ECOLOGICAL DRIVERS OF ANTIPREDATOR DEFENSES IN CARNIVORES

Mammals have evolved several morphological and behavioral adaptations to reduce the risk of predation, but we know little about the ecological factors that favor their evolution. For example, some mammalian carnivores have the ability to spray noxious anal secretions in defense, whereas other species lack such weaponry but may instead rely on collective vigilance characteristic of cohesive social groups. Using extensive natural history data on 181 species in the order Carnivora, we created a new estimate of potential predation risk from mammals and birds of prey and used comparative phylogenetic methods to assess how different sources of predation risk and other ecological variables influence the evolution of either noxious weaponry or sociality in this taxon. We demonstrate that the evolution of enhanced spraying ability is favored by increased predation risk from other mammals and by nocturnality, but the evolution of sociality is favored by increased predation risk from birds of prey and by diurnality, which may allow for enhanced early visual detection. These results suggest that noxious defenses and sociality are alternative antipredator strategies targeting different predator guilds under different lighting conditions.     

我国特有植物青檀遗传结构的ISSR分析

青檀是我国特有的第三纪残遗植物,是宣纸纤维来源的重要原材料,现已被列入国家Ⅲ级保护植物。采用简单序列重复区间扩增多态性(ISSR)标记技术,对采自27个地理种群的628个青檀个体的遗传多样性和遗传结构进行了检测。8对引物共得到66个清晰的扩增位点,其中多态性位点63个,多态性位点百分率为95.45%。分析结果表明,青檀在物种水平上具有很高的遗传多样性(PPB=95.45%、Ao=1.9545、Ae=1.5729、He=0.3335、I=0.4980、Hb=0.3437)。在种群水平上的遗传多样性(PPB=69.98%、Ao=1.6998、Ae=1.4449、He=0.2561、I=0.3793、Hb=0.2656)和种群间遗传分化水平(Gst=0.23,Ф_ST=0.25)均处于中等水平。华北地区(30°-42°N)和华南地区(22°-30° N)青檀的遗传多样性和遗传结构的差异并不显著。古老的起源历史、较广的分布范围、异交的繁育系统、风媒种子、长命的生活史以及华南和华北地形和植被的差异可能是导致青檀目前遗传格局的主要原因。结合叶绿体序列(cpDNA)序列的遗传结构特征对青檀的保护策略进行了探讨。     

Phylogenetic analysis of coadaptation in behavior, diet, and body size in the African antelope

Several authors have suggested that African antelope (familyBovidae) exemplify coadaptation of ecological, behavioral,and morphological traits. We tested four hypotheses relatedto the ecology and behavior of 75 species of African antelopeusing both conventional statistical techniques and techniques that account for the nonindependence of species by consideringtheir phylogenetic relationships. Specifically, we tested thehypotheses that (1) dietary selectivity is correlated negativelywith body mass, (2) dietary selectivity is correlated negativelywith group size, (3) gregarious species either flee or counterattackwhen approached by predators, but solitary and pair-livingspecies seek cover to hide, and (4) body mass and group sizeare correlated positively. Each of these hypotheses was examinedfor the global data set (family Bovidae) and, when possible,within the two antelope subfamilies (Antilopinae and Bovinae)and within 7 of the 10 antelope tribes. The results of ourconventional and phylogenetically corrected analyses supportedthe hypotheses that group and body size vary predictably with feeding style and that antipredator behavior varies with groupsize. The hypothesis that body mass and group size are correlatedpositively was supported by conventional statistics, but thesetwo traits were only weakly related using a phylogeneticallycorrected analysis. Moreover, qualitative and quantitativecomparisons within each of the eight major African antelope tribes generally gave little support for the four hypothesestested. Thus, although our analyses at the subfamily levelprovided results that were consistent with prior hypotheses,our analyses at the level of tribes were equivocal. We discussseveral possible explanations for these differences.     

山东南部景观生态对策研究

在对山东南部气候、地貌、土壤、植被等景观生态要素研究的基础上,以地貌和基质为基本线索、以植被为标志建立了该地区的景观生态分类系统．该系统为二级分类系统,包括７个景观型、１７个景观亚型,其中,景观型根据植被（植被型或栽培植被型）划分,景观亚型根据地貌、植被（群系组或栽培组合）划分．以景观亚型或景观亚型的组合为基本单位,以１∶１００万土壤图为基础底图,参考多种比例尺的卫星照片、植被图、土地利用图、地貌图等,编制了山东南部１∶１００万景观生态类型图;在景观生态类型图上量算了各景观亚型的面积．据此详细分析了山东南部稀疏植被景观、常绿针叶林景观、落叶阔叶林景观、旱地作物景观、水旱轮作景观、湖泊景观等主要景观型的生态问题,提出了相应的生态对策     

Parasitic worms: strategies of host finding, recognition and invasion

Many parasitic worms enter their hosts by active invasion. Their transmission success is often based on a mass production of invasive stages. However, most stages show a highly specific host-finding behaviour. Information on host-finding mechanisms is available mainly for trematode miracidia and cercariae and for nematode hookworms. The larvae find and recognise their hosts, in some cases even with species specificity, via complex sequences of behavioural patterns with which they successively respond to various environmental and host cues. There is often a surprisingly high diversity of host-recognition strategies. Each parasite species finds and enters its host using a different series of cues. For example, different species of schistosomes enter the human skin using different recognition sequences. The various recognition strategies may reflect adaptations to distinct ecological conditions of transmission. Another question is how, after invasion, parasitic worms find their complex paths through their host's tissues to their often very specific microhabitats. Recent data show that the migrating parasite stages can follow local chemical gradients of skin and blood compounds, but their long-distance navigation within the host body still remains puzzling.

The high complexity, specificity and diversity of host-recognition strategies suggest that host finding and host recognition are important determinants in the evolution of parasite life cycles.     

The Effect of Predator Chemical Cue Age on Antipredator Behavior in the Wolf Spider Pardosa milvina (Araneae: Lycosidae)

The wolf spider, Pardosa milvina, exhibits reduced movement when detecting chemical cues (silk and excreta) from a larger wolf spider, Hogna helluo. We tested if cue age influenced Pardosa activity. Pardosa response was measured during 1-h trials using video-tracking equipment. Five treatments of predator cues were used: 5-day-old, 1-day-old, 1-h-old, and fresh cues and a control lacking predator cues. Pardosa moved significantly more slowly on substrates with fresh or 1-h-old cues compared to all other treatments and spent less time walking in all Hogna treatments relative to the control except with 5-day-old cues. Pardosa survived longer in the presence of Hogna with fresh compared to older cues. Prey may evaluate cue age as a measure of predation risk and grade antipredator behavior accordingly.     

Dominance style of female white‐faced capuchins

Dominance style, the level of tolerance displayed by dominant individuals toward subordinate ones, is exhibited along a continuum from despotic to relaxed. It is a useful concept to describe the nature of dominance relationships in macaque species and it bridges among multiple features of dominance hierarchies, aggression, kinship and conflict resolution. Capuchins share many behavioral similarities with Old World monkeys and like macaques, may exhibit a suite of covarying characteristics related to dominance. Here, we provide an assessment of dominance style by examining measures of aggression and kin bias in 22 adult female white‐faced capuchin monkeys (Cebus capucinus) in three social groups at Santa Rosa Sector, Costa Rica. We found that bidirectionality of aggression was low (mean = 6.9% ± SE 1.6). However, there were few significant correlations between kin relatedness and social behavior (approaching, grooming, proximity, and co‐feeding), even though the intensity of kin bias in grooming was moderate and higher in the larger group. We conclude that patterns of aggression and kin‐biased behavior in our study animals are dissimilar to the patterns of covariation observed in macaque species. While unidirectional aggression suggests a despotic dominance style, the moderate expression of kin bias suggests an intermediate to relaxed classification when compared with results from an analysis of 19 macaque species. Additional studies of capuchin species and behaviors associated with dominance style (i.e., conciliatory tendencies) would help to create a comparative framework for the genus Cebus, and allow for more detailed cross‐species comparison of dominance relationships across all primates. Am J Phys Anthropol 150:591–601, 2013. © 2013 Wiley Periodicals, Inc.