首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   354篇
  国内免费   2篇
  完全免费   10篇
  2016年   2篇
  2015年   1篇
  2014年   1篇
  2013年   3篇
  2012年   1篇
  2011年   10篇
  2010年   11篇
  2009年   35篇
  2008年   28篇
  2007年   48篇
  2006年   32篇
  2005年   22篇
  2004年   23篇
  2003年   20篇
  2002年   17篇
  2001年   17篇
  2000年   10篇
  1999年   14篇
  1998年   18篇
  1997年   10篇
  1996年   4篇
  1995年   6篇
  1994年   5篇
  1993年   6篇
  1992年   3篇
  1991年   8篇
  1990年   3篇
  1989年   2篇
  1987年   6篇
排序方式: 共有366条查询结果,搜索用时 15 毫秒
1.
Determining the fitness consequences of antipredation behavior   总被引:17,自引:4,他引:13  
Any animal whose form or behavior facilitates the avoidanceof predators or escape when attacked by predators will havea greater probability of surviving to breed and therefore greaterprobability of producing offspring (i.e., fitness). Althoughin theory the fitness consequences of any antipredation behaviorcan simply be measured by the resultant probability of survivalor death, determining the functional significance of antipredationbehavior presents a surprising problem. In this review we drawattention to the problem that fitness consequences of antipredationbehaviors cannot be determined without considering the potentialfor reduction of predation risk, or increased reproductive output,through other compensatory behaviors than the behaviors understudy. We believe we have reached the limits of what we canever understand about the ecological effects of antipredationbehavior from empirical studies that simply correlate a singlebehavior with an apparent fitness consequence. Future empiricalstudies must involve many behaviors to consider the range ofpotential compensation to predation risk. This is because antipredationbehaviors are a composite of many behaviors that an animal canadjust to accomplish its ends. We show that observed variationin antipredation behavior does not have to reflect fitness andwe demonstrate that few studies can draw unambiguous conclusionsabout the fitness consequences of antipredation behavior. Lastly,we provide suggestions of how future research should best betargeted so that, even in the absence of death rates or changesin reproductive output, reasonable inferences of the fitnessconsequences of antipredation behaviors can be made.  相似文献
2.
3.
4.
The influence of predation risk on diet selectivity: A theoretical analysis   总被引:13,自引:0,他引:13  
Studies that have examined the effect of experimental increases in predation risk on diet selectivity have shown both decreased and increased diet selectivity. A possible explanation for these disparate results emerges from an examination of the prey sets used in these studies, which differed in the relationship between the values of risk components associated with the capture of different prey types (‘danger’) and their profitabilities. When less profitable prey were more dangerous, selectivity increased with predation risk. When prey were equally dangerous, selectivity did not change. Finally, when the more profitable prey were also more dangerous, selectivity decreased with risk. Here, we examine theoretically the influence of a forager's estimate of the probability that a predator is present (φ) on the selection of diets from prey sets with varying danger–profitability relationships. A dynamic programming model is used to determine the maximum attack time (or distance) for each of two types of prey, differing in their energetic content, for a range of forager energy state and φ levels. The diets which would result if foragers attacked prey according to the rules provided by the dynamic model are then determined. The model results indicate that the prey danger–profitability relationship determines the diet selectivity response to φ, confirming that variation in this relationship could be responsible for the range of experimental results. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献
5.
捕食风险及其对动物觅食行为的影响   总被引:13,自引:0,他引:13  
对捕食风险的涵义及其对猎物动物觅食行为的影响、猎物动物面对捕食风险时的反应进行了论述。捕食风险可以简单地理解为一定时间内猎物动物被杀死的概率。当捕食风险存在时 ,动物会选择相对安全但觅食效益较低的地点觅食 ;由于死亡率和消化方面的限制 ,一般都会产生食谱收缩 ;觅食活动方式的时间格局也会因捕食风险而发生改变 ,如水生动物的昼夜垂直迁移、某些陆生动物昼行性与夜行性活动的转换、月光回避等。在与捕食者发生遭遇时 ,猎物动物的主要反应是 :①发出某些信号以阻止捕食者的追捕 ;②靠近并注视捕食者 ;③逃逸 ;④在一定的时间恢复觅食活动。在以往的研究中 ,对捕食者种类已经有了较多的了解 ,而对猎物如何判断捕食者丰富度信息、估计风险程度等方面则知之甚少 ;同时 ,对捕食风险水平的调控、对多种因素的综合分析也较少涉及。在今后的研究中 ,还应该考虑研究的尺度问题 ,因为在不同尺度的环境条件下 ,猎物动物对于捕食风险的反应可能大相径庭。  相似文献
6.
There is concern that the progeny resulting from the spawnings of escaped farmed Atlantic salmon may compete with and disrupt native salmon populations. This study compared, both in the hatchery and in the wild, fitness-related traits and examined interactions among farmed, native and hybrid 0+ parr derived from controlled crosses and reared under common conditions. The farmed salmon were seventh-generation fish from the principal commercial strain in Norway and native salmon were from the rivers Imsa and Lone, Norway. In the hatchery, farmed salmon were more aggressive than both native populations and tended to dominate them in pairwise contests. Farmed salmon were also more prone to risk, leaving cover sooner after a simulated predator attack, and had higher growth rates than native fish. Interbreeding between farmed and native fish generally resulted in intermediate expression of the above traits. There was, however, evidence of hybrid vigour in Lone/farmed crosses which were able to dominate both pure Lone and farmed parr in pairwise contests. In the wild, observations of habitat use and diet suggested that the populations compete for territory and food, and both farmed fish and hybrids expressed higher growth rates than native fish. Our results suggest that these innate differences in behaviour and growth, that probably are linked closely to fitness, will threaten native populations through competition and disruption of local adaptations.  相似文献
7.
Hazardous duty pay and the foraging cost of predation   总被引:11,自引:0,他引:11  
8.
9.
动物觅食行为对捕食风险的反应   总被引:10,自引:1,他引:9       下载免费PDF全文
动物进行任何活动时均面临被捕食的风险 ,分析捕食风险与猎物觅食行为的关系 ,有助于揭示捕食者与猎物的协同进化机制。捕食风险具有限制或调节猎物种群数量的功能。在进化时间内 ,对猎物形态和行为特征的进化是潜在的选择压力之一 ,可利用环境因子作为信息源估测食物可利用性和捕食风险大小的动物 ,具有更大的适合度。信息源可分为包括视觉的、听觉的和化学的。动物进行觅食活动时 ,依据信息源的变化确定环境中捕食风险的大小 ,并根据自身的质量在捕食风险的大小之间做出权衡 ,通过食物选择、活动格局和栖息地利用等行为的变化降低捕食风险  相似文献
10.
State dependent behavior and the Marginal Value Theorem   总被引:9,自引:5,他引:4  
The Marginal Value Theorem (MVT) is the dominant paradigm inpredicting patch use and numerous tests support its qualitativepredictions. Quantitative tests under complex foraging situationscould be expected to be more variable in their support becausethe MVT assumes behavior maximizes only net energy-intake rate.However across a survey of 26 studies, foragers rather consistently"erred" in staying too long in patches. Such a consistent directionto the errors suggests that the simplifying assumptions ofthe MVT introduce a systematic bias rather than just imprecision. Therefore, I simulated patch use as a state-dependent responseto physiological state, travel cost, predation risk, prey densities,and fitness currencies other than net-rate maximization (e.g.,maximizing survival, reproductive investment, or mating opportunities).State-dependent behavior consistently results in longer patchresidence times than predicted by the MVT or another foragingmodel, the minimize µ/g rule, and these rules fail to closely approximate the best behavioral strategy over a widerange of conditions. Because patch residence times increasewith state-dependent behavior, this also predicts mass regulationbelow maximum energy capacities without direct mass-specificcosts. Finally, qualitative behavioral predictions from theMVT about giving-up densities in patches and the effects oftravel costs are often inconsistent with state-dependent behavior.Thus in order to accurately predict patch exploitation patterns,the model highlights the need to: (1) consider predator behavior(sit-and-wait versus actively foraging); (2) identify activitiesthat can occur simultaneously to foraging (i.e., mate searchor parental care); and (3) specify the range of nutritional states likely in foraging animals. Future predictive modelsof patch use should explicitly consider these parameters.  相似文献
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号