Prior contest information: mechanisms underlying winner and loser effects

Animals’ contest performance is influenced by their recent contest experiences. This influence could either be exerted by individuals re-estimating their own fighting ability (self-assessment) or by their opponents responding to status-related cues (social-cue mechanism) or both. Individuals of Kryptolebias marmoratus, a hermaphroditic killifish, were given different contest experiences to examine how two opponents’ prior experiences combined to determine their contest interaction and to test both of these mechanisms as potential causes of the observed experience effect. Our data showed that losers’ decisions to retreat at different stages of a contest were influenced by their own but not by the winners’ contest experience—a result consistent with self-assessment but not with the social-cue mechanism. An association between the fish initiating and winning contests thus probably arose because both were correlated with an individual’s assessment of its fighting ability, but not because initiating contests made opponents more inclined to retreat.     

Fighting without weaponry: a review of male-male contest competition in butterflies

The males of many butterfly species compete via pair-wise intrasexual contests, yet lack any obvious morphological traits conventionally associated with animal aggression. The evolution of contest behavior in this group is therefore interesting because the means by which individuals are able to inflict costs upon each other during combat are unclear. Here we review the relevant empirical information within a game-theoretical context in order to analyze contest-related costs and mechanisms of dispute settlement. Territorial butterfly contests carry obvious role asymmetries, and individuals in the 'resident' role are more likely to win across all studied species. We use this phenomenon as a framework for gaining further insight into the evolution of contest settlement in this group. Four principal hypotheses are evaluated: (1) that residency is used as an arbitrary convention, (2) that residents stand to gain a greater payoff if successful, (3) that residency bestows higher resource-holding potential (RHP) on males in that role, and (4) that residents are males of intrinsically higher RHP. We found most support for the latter explanation (the 'superior-competitor' hypothesis), partly because the alternatives require a restrictive set of ecological conditions, but also due to positive support for the idea of intrinsic RHP. The strongest evidence is provided by species in which repeated interactions (between the same individuals) always have the same outcome, regardless of changes in residency status. However, we also found a consistent effect on contest duration due to apparent 'confusion over residency,' which suggests a conventional element to contest behavior. Although butterfly contests must be costly in some way, the literature provides limited insight into how costs accrue, and hence the determinants of contest RHP remain obscure. We suggest that careful experimentation, using 'natural' manipulations where possible, should prove most beneficial in identifying costs and exploring schedules of contest settlement in this group. Moreover, future investigations should be sensitive to the fact that butterfly territoriality and associated male-male interactions are seated within a broader ecological and life-historical context.     

Intratree vertical variation of fruit density and the nature of contest competition in frugivores

Recently, we demonstrated that the highest densities of fruit pulp are located in the uppermost zones of tree crowns. Since heterogeneous distributions of depletable food is theorized to foster contest competition, we tested three hypotheses involving rank differences among species of arboreal frugivores: (1) In the absence of competitors, species tend to feed in higher strata of tree crowns; (2) interspecific contest competition occurs through monopolization and usurpation of feeding sites in these higher strata; and (3) subordinate species decrease their feeding height and ingestion rate when dominants enter the food patch. To test these hypotheses, we observed chimpanzees (Pan troglodytes), red-tailed monkeys (Cercopithecus ascanius), blue monkeys (Cercopithecus mitis), and gray-cheeked mangabeys (Lophocebus albigena) in Kibale National Park, Uganda. We found that: (1) all four primates fed preferentially in upper tree crowns when alone, (2) dominant species monopolized and aggressively usurped the upper crown when co-feeding with subordinates and the latter retreated below the middle of tree crowns, (3) in the presence of dominant species, subordinate species showed lower standardized feeding height and modified their food intake rates, while dominants were not affected by the subordinate species, (4) subordinates moved down at the arrival of and up at the departure of dominants, and (5) the presence of folivores in the tree did not affect the feeding height of a frugivore, even through folivores were socially dominant. Contrary to expectations, we found that red-tailed monkeys decreased their movements between successive fruits that they ate in the presence of blue monkeys compared to when they were feeding alone, perhaps to avoid disturbing dominants and attracting aggression or because they ingested more semi-ripe and green unripe fruits, i.e., more food of lower quality.     

Rival recognition affects male contest behavior in sand lizards (Lacerta agilis)

Individual male sand lizards meet repeatedly during mate search and engage in costly interactions. If males can recognize rivals, the number of costly fights with a predictable outcome may be reduced. In staged contests between males, second interactions are on average significantly shorter than first ones, suggesting individual recognition. When aggressive behavior differs substantially between the sexes, the more aggressive sex may be predicted to have more variation in skin traits located on the parts of the body displayed during contests; this would facilitate individual recognition. Male (aggressive) sand lizards are more variable in two of three lateral skin traits displayed during males' contests, while females (non-aggressive) are more variable in one dorsal skin trait; in four other dorsal traits there was no difference in variability between the sexes.     

Exaggerated male eye span influences contest outcome in stalk-eyed flies (Diopsidae)

Evolution of male weapons or status signals has been hypothesized to precede evolution of female mating preferences for those traits. We used staged male fights among three species of Malaysian stalk-eyed flies (Diptera: Diopsidae) to determine if elongated eye span, which is preferred by females in two sexually dimorphic species, influences contest outcome. Extreme sexual dimorphism, with large males possessing longer eye span than females, is shared by Cyrtodiopsis whitei and C. dalmanni. In contrast, C. quinqueguttata exhibits a more ancestral condition – short, sexually monomorphic eye stalks. Videotape analysis of 20-min paired contests revealed that males with larger eye span and body size won more fights in the dimorphic, but not monomorphic, species. To determine if males from the dimorphic species use eye span directly to resolve contests, we competed male C. dalmanni from lines that had undergone artificial selection for 30 generations to increase or decrease eye span. We found that eye span, independently of body size, determines contest outcome in selected-line males. Furthermore, in both dimorphic species, the average encounter duration declined as the eye span difference between contestants increased, as expected if males use eye span to assess opponent size. The number of encounters also increased with age in dimorphic, but not monomorphic, species. Selected-line males did not differ from outbred males in either fight duration or number of encounters. We conclude that exaggerated male eye stalks evolved to influence both competitive interactions and female mating preferences in these spectacular flies. Received: 20 July 1998 / Received in revised form: 2 February 1999 / Accepted: 12 March 1999     

Proximate mechanisms of contest competition among female Bwindi mountain gorillas (Gorilla beringei beringei)

Socioecological models provide a framework for predicting how animals respond competitively to the abundance and distribution of food resources. Testing predictions of socioecological models requires analysis of relationships among food resource characteristics, competitive behaviors, and measures of rank-related skew in energy balance or reproductive success. A positive relationship between dominance rank and energy balance has been observed among female mountain gorillas in Bwindi Impenetrable National Park, Uganda. This study examines the proximate mechanisms underlying feeding competition among those females. To assess the contestability of food resources, we measured the time a female spent feeding at a food site (food site residence time). We also examined the relationship between dominance rank and the access to resources, as well as the rate, context, and direction of aggression, and the number of neighbors in close proximity. As predicted, females had longer food site residence times and higher aggression rates with fruit and decaying wood than with herbaceous vegetation, suggesting that those resources may be contestable. Aggression was predominantly directed down the dominance hierarchy, although against expectation, rank was not significantly correlated with aggression rates or the time spent feeding on contestable foods. Higher-ranking females had significantly fewer neighbors, suggesting that lower-ranking females avoid higher-ranking ones. This study provides additional support for the claim that there is variability in how primates respond to the quality and distribution of food resources and that avoidance as a strategy to cope with feeding competition may result in similar skew in energy balance as rank-related aggression.     

Causes and consequences of contest outcome: aggressiveness, dominance and growth in the sheepshead swordtail, Xiphophorus birchmanni

Although our understanding of how animal personality affects fitness is incomplete, one general hypothesis is that personality traits (e.g. boldness and aggressiveness) contribute to competitive ability. If so, then under resource limitation, personality differences will generate variation in life history traits crucial to fitness, like growth. Here, we test this idea using data from same-sex dyadic interaction trials of sheepshead swordtails (Xiphophorus birchmanni). In males, there was evidence of repeatable variation across a suite of agonistic contest behaviours, while repeatable opponent effects on focal behaviour were also detected. A single vector explains 80 % of the among-individual variance in multivariate phenotype and can be viewed as aggressiveness. We also find that aggressiveness predicts dominance—the repeatable tendency to win food in competition—and dominant individuals show faster post-trial weight gain (independently of initial size). In females, a dominance hierarchy predictive of weight gain was also found, but there was no evidence of variation in aggressiveness. While size often predicts contest outcome, our results show that individuals may sometimes grow larger because they are behaviourally dominant rather than vice versa. When resources are limited, personality traits such as aggression can influence growth, life history, and fitness through impacts on resource acquisition.     

Rank differences in energy intake rates in white-faced capuchin monkeys, Cebus capucinus: the effects of contest competition

The effect of aggressive competition over food resources on energy intake rate is analyzed for individuals of three groups of 25–35 white-faced capuchin monkeys, Cebus capucinus, living in and near Lomas Barbudal Biological Reserve, Costa Rica. An individuals energy intake rate on a given food species was affected by its rank and the number of agonistic interactions within the feeding tree. Dominant group members had higher energy intake rates relative to subordinate group members whether or not there was agonism within the feeding tree. Low- and mid-ranked individuals had lower energy intake rates in trees with higher amounts of aggression, while energy intake rate of high-ranked individuals was not affected by the amount of aggression in the feeding tree. Energy intake was not influenced by the sex of the individual when rank was held constant statistically. Energy intake was positively correlated with total crown energy (measured in kilojoules) within the feeding tree for two of three study groups. This difference may be explained by the quality of each groups territory. Finally, high-ranked individuals are responsible for the majority of agonism within feeding trees and target middle- and low-ranked individuals equally. These findings fit the predictions of current socioecological models for within-group contest competition over food resources. The results of this study suggest that within-group competition affects energy intake rate in white-faced capuchin monkeys.     

The enemies within: intergenomic conflict, interlocus contest evolution (ICE), and the intraspecific Red Queen

Different loci within the genome of a single species can potentially coevolve in a manner that is analogous to the Red Queen process among species. The major factor driving this antagonistic coevolution among loci is intergenomic conflict, i.e., discord between individuals that is mediated by two or more gene products that are derived from different gene loci. We conclude that antagonistic coevolution is common among loci that code for social interactions, and that it has broad evolutionary implications, especially in the context of speciation and sex chromosome evolution. Received: 15 January 1997 / Accepted after revision: 14 April 1997     

Between-group contest competition for food in a highly folivorous population of black and white colobus monkeys (Colobus guereza)

In theory, between-group contest (BGC) competition for food can greatly influence female social relationships and reproductive success in primates, but few studies have investigated whether such effects occur and, if so, under what ecological conditions. There is evidence that adult male black and white colobus monkeys (Colobus guereza, “guerezas”) defend the food their mates need against other groups, suggesting that BGC competition is important in this species. Using data on feeding, ranging, vegetation patterns, and intergroup encounters between six neighboring guereza groups, I provide evidence that the highly folivorous guerezas at Kanyawara, Kibale National Park, Uganda, engaged in BGC competition over unevenly dispersed, relatively high-quality feeding areas or “core areas”. Intergroup aggression was common, and groups’ home ranges overlapped. Groups were more likely to initiate high-level aggression if they encountered another group within or near their core area, and groups that initiated and won encounters often fed in the same areas in which losing groups had fed. Guerezas fed selectively on species with contagious (clumped) distributions and concentrated their feeding efforts in areas of the forest that contained the most food (core areas). Groups could be ranked in a linear dominance hierarchy, and group rank number was inversely related to the quantity and quality of food in groups’ core areas. This study not only provides good evidence that BGC competition occurs in primates but it also reinforces the idea that folivore food resources may be worth defending.     

The role of body size and fighting experience in predicting contest behaviour in the black field cricket, <Emphasis Type="Italic">Teleogryllus commodus</Emphasis>

Body size strongly predicts fighting behaviour and outcome in many species, with the larger opponent usually winning contests. However, recent fighting experience can have a strong influence on the establishment of dominance hierarchies, with recent winners being more likely to win subsequent contests, while recent losers are more likely to lose. Recent fighting experience therefore has the potential to modify the effect of body size in determining contest behaviour and outcome. Here, we investigate whether recent fighting experience weakens the role of body size in predicting contest behaviour in the black field cricket, Teleogryllus commodus. We compared the role of body size in determining contest outcome during initial non-physical encounters and escalated aggressive physical encounters (grapples), as well as the probability of escalation occurring, in contests involving either a naïve or experienced smaller male against a naïve larger male. We found that recent fighting experience only affected contest outcome during non-physical encounters. Once a contest had escalated into grappling, the effect of previous wins and losses was no longer apparent and body size strongly predicted contest outcome. Thus, once males can directly assess their opponent's fighting ability, recent fighting experience did not alter the effect of body size on contest behaviour and outcome.     

Induction of metamorphosis of two species of sea urchin from Sea of Japan

The induction of metamorphosis in mature larvae by selected chemical compounds and natural substrata was investigated in two species of sea urchins from the Sea of Japan, Strongylocentrotus intermedius and Scaphechinus mirabilis. Glutamine in crystalline form was added directly to water containing mature larvae, and this compound, at a final concentration of 10 g ml^-1, was an inducer of metamorphosis in S. intermedius (100% activity) and S. mirabilis (50% activity). Gutamine, or its natural mimetic molecules, may be an active component of the exogenous cue that induces metamorphosis of S. intermedius larvae. This exogenous cue was produced by the epiphytic calcareous algae, Melobesia spp. that colonized the older sea grass Zostera marina. Glutamic acid was also used as an inducer of metamorphosis for S. intermedius and S. mirabilis larvae (50 to 60% activity), but it was toxic to the larvae.     

1株微小杆菌对4种蓝藻的生长影响

利用过滤的天然珍珠养殖水参照BG11配制加富培养液,将1株能促进鱼害微囊藻生长的微小杆菌属菌株(Exiguobacterium sp.013,简写为E.sp.013)进行纯化扩大培养后与铜绿微囊藻(Microcystis aeruginosa)、水华微囊藻(Microcystis flosaquae)、平裂藻(Merismopedia sp.)和惠氏微囊藻(Microcystis wesenbergii)按一定菌、藻密度比例同时接种后进行为期24 d的培养试验,利用特定生长率和细胞密度等指标观察并检验E.sp.013菌株对4种蓝藻生长的影响,同时检测培养液中优势菌群的数量变化趋势.结果表明:E.sp.013菌对铜绿微囊藻、水华微囊藻和惠氏微囊藻具有显著促生长和延长稳定生长期作用,对平裂藻不具有显著促生长作用,但对延长其稳定生长期具有显著效果;试验培养过程中E.sp.013菌落数量占所有菌落总数的比例始终高于46％,处于绝对优势地位,表明E.sp.013菌具有调控其他菌群的能力.     

南京城市西部遗产廊道规划

南京城市西部历史时期是城市的重要边界,现在逐渐演变成老城与新区之间的核心地带,成为公共活动的重要地区,保护其自然、文化遗产和生态环境具有非常重要的意义。在对其现状调查分析的基础上,梳理遗产点的历史概况、现状及其分布情况,提出规划遗产廊道的意义,探讨规划的具体思路,为南京遗产保护提供了新的视角。     

《生态毒理学报》主编简介

<正>王子健,男,1953年10月出生,博士,研究员,博士生导师．1976年中国科技大学毕业后到中科院生态环境研究中心工作．1983-1985年在瑞士留学,从事水质污染化学规律研究;1987年在日本从事生物样品生理活性物质分析方法研究． 1992-2000年担任中科院生态环境研究中心环境水化学国家重点实验室副主任、主任,兼环境模拟与污染控制国家重点联合实验室学术委员会委员,国家863计划污染控制技术主题专家组副组长,国家自然科学基金委员会地球科学部第二届咨询专家委员会委员,国际环境地球化学与健康学会亚太分会理事,全球环境基金专家库成员等．同时担任环境科学学报(副主编)、过程工程学报、环境化学、湿地研究、地球与环境、美国Environmental Science and Health(A)等杂志的编委．王子健领导的研究小组主要研究天然水体和水处理过程中的水质转化、相关毒性和毒理变化以及健康和生态风险．内容包括发展新的环境监测技术,离体和活体生物毒性测试方法,污染物水体多介质过程,水质安全性评价以及水污染的健康和生态风险的指标和方法．在开发新型生物模拟采样技术和生物毒性测试方法体系、生活饮用水和再生水的安全性评价、持久性有毒污染物污染及其生态与健康影响等方面取得了丰硕的成果,相当一部分成果得到推广应用．     

Evaluation of adsorption potential of adsorbents: a case of uptake of cationic dyes

Adsorption potential of a commercial activated carbon (FS300) has been evaluated for the uptake of cationic dyes namely methylene blue (MB) and rhodamine B (RB). Though, there are numerous studies in literature which report the sorption of MB (more than 40 studies) and RB (more than 10), however none of these use a common parameter to report the capacity of the sorbent. A protocol, based on the equilibrium dye concentration has been proposed to measure the sorption potential of a sorbent. The Langmuir model can very well describe the experimental equilibrium data for both dyes (coefficient of correlation > 0.999). MB (Qm = 312.5 mg g(-1)) is more adsorbable than the RB (Qm = 144.9 mg g(-1)). Molecular weight and chemical structure of dye molecules seem to affect the dye uptake. The effect of pH on dye uptake has also been evaluated by varyingpH from 3 to 11. Uptake of MB increases with pH, wherein RB removal decreases with pH. Dyes could not be desorbed either by distilled water (0.06 and 0.11% for MB and RB respectively), or by 0.1 NHCl (0.136 and 3.0% for MB and RB respectively) indicating, chemical adsorption type of adsorbent-adsorbate interactions.     

利用回归分析确定降水入渗补给量

目前常用降水量乘以降水入渗补给系数的方法计算降水入渗补给量,此法不能表现降水特征、蒸发等因素对降水入渗补给的影响．为解决不同时间尺度、不同降水特征和蒸发情况下的降水入渗补给量,在分析郑州地下水均衡试验场地中渗透仪实测入渗量、降水和蒸发资料的基础上,利用均匀设计法选取最优的与降水入渗补给量关系密切的前期降水量和蒸发量的期次,然后利用回归分析建立各岩性和埋深的年、月和日尺度上的降水入渗函数,可以比较准确的计算降水入渗补给量．表3,参9．     

洞庭湖生态环境承载力分析

洞庭湖湖内冬枯水季节，有芦苇面积530km^2，草地面积800余km^2，泥滩地面积367km^2，天然水域面积约993km^2。湖洲之间隔水相望，河沟水系纵横交错，具“水浸皆湖，水落为洲”的地貌特征，呈现出支离破碎的形态面貌和典型的自然湿地景观。文章在大量调查的基础上，从自然和人文两个方面对洞庭湖的生态环境承载力或环境压力进行分析。     

接种污泥源对厌氧氨氧化启动效能的影响

厌氧氨氧化(anaerobic ammonium oxidation,ANAMMOX)菌生长缓慢是影响其实际应用的主要问题之一,选取合适的接种污泥十分重要.本研究采用好氧污泥、厌氧颗粒污泥和厌氧消化污泥3种接种污泥,分别经过61、70和85 d的运行均实现了厌氧氨氧化过程,氨氮去除率分别为82%、92%和91%,总氮去除率达76%、82%和80%.分别接种3种污泥源的厌氧序批式反应器(ASBR)R1、R2、1t3出水pH值最终稳定在8.4、8.5、8.5.好氧污泥呈絮状,但沉降性比接种前好,厌氧颗粒污泥解体后最终形成粒径集中在0.5～1.0 mm的污泥,厌氧消化污泥则呈沙化状态,有细小颗粒出现.根据厌氧氨氧化细胞产率系数及NH4+-N、NO2--N去除量和NO3--N生成量之间的计量学关系,估算出厌氧氨氧化菌产率系数(以1 mol NH4+产生的CH2O0.5N0.15量计)分别为0.080、0.105和0.114 mol·mol-1,说明反应器内厌氧氨氧化菌有不同程度的衰减.总体而言,厌氧颗粒污泥是富集厌氧氨氧化菌的最适污泥源.