Effects of density on foraging success and aggression in age-structured groups of brown trout
Effects of density on foraging success and aggression in age-structured groups of brown trout
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DOI：
10.1016/j.anbehav.2009.12.025
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发表时间：
2010-03-01
期刊：
影响因子：
2.5
通讯作者：
Pedersen, Stig
中科院分区：
文献类型：
--
作者：
Kaspersson, Rasmus;Hojesjo, Johan;Pedersen, Stig
垄断有限资源的利益受到竞争者密度以及防御者和入侵者的相对竞争能力的影响。然而，很少有研究调查的影响，密度对资源的防御在竞争能力的大不对称的群体，作为一个结果，例如，年龄和/或身体大小。我们使用了两个年龄组（即大小组）的流生活褐鳟鱼，萨尔莫trutta，调查这个问题。虽然老（和大）鳟鱼被认为是上级在干扰竞争，年轻的个人可能都是数字上占主导地位，并构成总人口生物量的一半以上。本试验在室内人工溪流中，以0、2、6和12岁4种密度的1岁以下幼鱼为研究对象，观察了1岁以下幼鱼对集中食物源的独占能力。我们预测，成功的国防将减少与下一岁的密度和国防（即侵略）的频率将在一个中等密度的峰值。正如所预测的那样，一岁鸽明显更不成功的觅食尝试，并通过深色体着色在高密度的一岁以下的幼鸽，这表明压力水平增加。然而，与我们的第二个预测相反，攻击性相互作用的数量随着密度的增加而逐渐增加。这些新的研究结果表明，防御的成本增加与一岁以下的密度，可能是由于压力的干扰与一岁以下的采用替代竞争策略。然而，大小的差异，似乎使一岁鸽捍卫食物资源在更高密度的竞争对手比预测的资源防御理论。(C)2009年，动物行为研究协会。由爱思唯尔有限公司出版。保留所有权利。
The benefit of monopolizing a limited resource is influenced by competitor density and by the relative competitive ability of defenders and intruders. Nevertheless, few studies have investigated the effect of density on resource defence in groups with large asymmetries in competitive ability, as a consequence of, for example, age and/or body size. We used two age classes (i.e. size groups) of stream-living brown trout, Salmo trutta, to investigate this issue. While old (and large) trout are assumed to be superior during interference competition, younger individuals may be both numerically dominant and constitute more than half of the total population biomass. In this experiment, the ability of one yearling to monopolize a concentrated food source was observed at four densities of under-yearlings (zero, two, six and 12) in an indoor seminatural stream. We predicted that the success of defence would decrease with increasing under-yearling density and that the frequency of defence (i.e. aggression) would peak at an intermediate density. As predicted, yearlings made significantly more unsuccessful foraging attempts and adopted darker body coloration at high density of under-yearlings, suggesting increased stress levels. However, in contrast to our second prediction, the number of aggressive interactions increased progressively with density. These novel findings suggest that the cost of defence increases with under-yearling density, probably as a consequence of stress from interference with under-yearlings employing alternative competitive strategies. However, the difference in size seems to enable yearlings to defend the food resource at higher density of competitors than predicted from the resource defence theory. (C) 2009 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.