Evolution and Ecology Research Centre, and School of Biological, Earth and Environmental Science, University of New South Wales, Sydney 2052, Australia.
J Fish Biol. 2011 Apr;78(4):1183-99. doi: 10.1111/j.1095-8649.2011.02926.x.
Dietary analysis revealed that an impoundment population of Australian bass Macquaria novemaculeata holds a generalist niche, but one arising from persistent individual specialization and interindividual variation. This 'individual specialist' strategy appeared adaptive, but the strength of individual specialization was largely independent of variation in diet composition, except during blooms of Daphnia sp. Diet composition and dietary overlap showed only moderate ontogenetic variation, and niche breadth showed no relationship with ontogeny. Macquaria novemaculeata showed an asymmetric predator and prey size distribution, consistent with many aquatic predators, with positive relationships between fish size and average, maximum and minimum prey size. There was no asymmetry in the relative size-based niche breadths of individuals, however, which indicates that the niche is a fixed 'window' of relative prey sizes. The difference in the dietary niche and prey-size relationships of M. novemaculeata at the population and individual levels highlights the necessity of assessing the niche at both these levels.
饮食分析表明，人工湖中的麦氏副麦鱚具有一种广义的生态位，但这种生态位是由个体的持续特化和个体间的变异形成的。这种“个体特化”策略似乎是适应性的，但个体特化的强度在很大程度上与饮食组成的变化无关，除非在水蚤属大量繁殖时。饮食组成和饮食重叠仅显示出适度的个体发育变化，生态位宽度与个体发育无关。麦氏副麦鱚表现出一种不对称的捕食者和猎物大小分布，与许多水生捕食者一致，鱼类大小与平均、最大和最小猎物大小之间存在正相关关系。然而，个体之间的相对生态位宽度没有不对称性，这表明生态位是一个相对固定的猎物大小“窗口”。麦氏副麦鱚在种群和个体水平上的饮食生态位和猎物大小关系的差异，突出了在这两个水平上评估生态位的必要性。
