An Experimental Separation of Interference and Exploitative Competition in Larval Damselfly
An Experimental Separation of Interference and Exploitative Competition in Larval Damselfly
复制标题
豆娘幼虫干扰与利用性竞争的实验分离
作者：
B. Anholt
密度依赖性减少幼虫豆娘的生存，生长和发育速率可能是由于耗尽的食物资源或增加的干扰成本（能量或时间）与行为的相互作用。虽然在几项研究中涉及干扰，但没有尝试通过操纵相互作用频率或强度来直接检验这一假设。为了分离这些机制，我同时操纵栖息地的复杂性（栖息的数量），以改变行为的相互作用，幼虫密度和食物供应的频率。豆娘成为更均匀地分布在可用的栖息地，每栖息密度的增加，表明有行为反应的操纵栖息地的复杂性。食物供应和豆娘密度强烈影响生存，出现的时间，并在出现质量。然而，在这些性能变量的变化归因于生境复杂性操纵的比例是微小的。尽管个人之间的互动具有明显的性质，但成本似乎很低。未来的工作，涉及行为机制在人口过程中将不得不尝试更直接的操纵行为本身来测试的假设，然后得出结论，行为是一个观察到的模式的原因。
Density-dependent reduction in survival, growth, and development rates of larval damselflies can be the result of depletion of food resources or increased interference costs (energy or time) associated with behavioral interactions. While interference has been implicated in several studies, no direct test of this hypothesis by manipulating interaction frequency or intensity has been attempted. To separate these mechanisms, I simultaneously manipulated habitat complexity (number of perches) to alter the frequency of behavioral interactions, larval density, and food supply. Damselflies became more evenly distributed among available perches as the density per perch increased, demonstrating that there were behavioral responses to the manipulation of habitat complexity. Food supply and damselfly density strongly affected survival, timing of emergence, and mass at emergence. However, the proportion of the variation in these performance variables attributable to the habitat complexity manipulation was tiny. In spite of the overt nature of the interactions among individuals, the costs appear to be very low. Future work that implicates behavioral mech- anisms in population processes will have to attempt more direct manipulations of the behavior itself to test the hypothesis before concluding that behavior is the cause of an observed pattern.