Schindler D E, Hodgson James R, Kitchell James F
Center for Limnology, University of Wisconsin, 680 N. Park St., Madison, WI 53706, USA, , , , , , US.
Department of Biological Sciences, St. Norbert College, DePere, Wisconsin, WI 54115, USA, , , , , , US.
Oecologia. 1997 May;110(4):592-600. doi: 10.1007/s004420050200.
Individual foraging specializations are an important source of intraspecific variability in feeding strategies, but little is known about what ecological factors affect their intensity or development. We evaluated stomach contents in marked individual largemouth bass (Micropterus salmoides) and tested the hypothesis that diet specialization is most pronounced during periods with high conspecific densities. We collected diet data over 10 years from an unexploited population of largemouth bass that displayed a greater than threefold variation in density. Although diet composition of the aggregate bass population did not change during the study, bass body condition was inversely correlated with population size. Individual marked bass exhibited high diet consistency (diet overlap between successive captures) during years with high population densities. Diet overlap between randomly assigned pairs of bass was not correlated with population size. We did not detect the expected positive relationship between diet breadth and population size. Our analyses demonstrate that population responses to density changes may represent the sum of many unique individual foraging responses and would be obscured by pooled sampling programs. Behavioral flexibility of individuals may contribute to the ability of largemouth bass to function as a keystone predator in many aquatic communities.
个体觅食专业化是摄食策略中种内变异性的一个重要来源，但对于哪些生态因素会影响其强度或发展，我们却知之甚少。我们评估了有标记的大口黑鲈（Micropterus salmoides）个体的胃内容物，并检验了以下假设：在同种密度较高的时期，食性专业化最为明显。我们从一个未被开发的大口黑鲈种群中收集了长达10年的食性数据，该种群的密度变化超过三倍。尽管在研究期间，大口黑鲈总体种群的食性组成没有变化，但大口黑鲈的身体状况与种群规模呈负相关。在种群密度较高的年份，有标记的大口黑鲈个体表现出较高的食性一致性（连续捕获之间的食性重叠）。随机配对的大口黑鲈之间的食性重叠与种群规模无关。我们没有检测到食性广度与种群规模之间预期的正相关关系。我们的分析表明，种群对密度变化的反应可能代表了许多独特个体觅食反应的总和，并且会被汇总采样程序所掩盖。个体的行为灵活性可能有助于大口黑鲈在许多水生群落中作为关键捕食者发挥作用。
