Schmitt Russell J, Holbrook Sally J
Department of Biological Sciences and Marine Science Institute, University of California, 93106, Santa Barbara, CA, USA.
Oecologia. 1984 Jul;63(1):6-12. doi: 10.1007/BF00379778.
Patterns of prey size selectivity were quantified in the field for two species of marine microcarnivorous fish, Embiotoca jacksoni and Embiotoca lateralis (Embiotocidae) to test Scott and Murdoch's (1983) size spectrum hypothesis. Two mechanisms accounted for observed selectivity: the relative size of a fish in relation to its prey, and the type of foraging behavior used. Juvenile E. jacksoni were gape limited and newborn individuals achieved highest selectivity for the smallest prey size by using a visual picking foraging strategy. As young E. jacksoni grew, highest preference shifted to the next larger prey sizes. When E. jacksoni reached adulthood, the principal mode of foraging changed from visual picking to relatively indiscriminant winnowing behavior. The shift in foraging behavior by adults was accompanied by a decline in overall preference for prey size; sizes were taken nearly in proportion to their relative abundance. Adult E. lateralis retained a visual picking strategy and achieved highest selectivity for the largest class of prey. These differences in selectivity patterns by adult fish were not explained by gape-limination since adults of both species could ingest the largest prey items available to them. These results support Scott and Murdoch's (1983) hypothesis that the qualitative pattern of size selectivity depends largely on the range of available prey sizes relative to that a predator can effectively harvest.
为了验证斯科特和默多克（1983年）的大小谱假说，对两种海洋微肉食性鱼类——杰克逊氏矶鲈（Embiotoca jacksoni）和侧条矶鲈（Embiotoca lateralis，矶鲈科）在野外的猎物大小选择模式进行了量化。观察到的选择性由两种机制导致：鱼相对于其猎物的相对大小，以及所采用的觅食行为类型。幼年杰克逊氏矶鲈受口裂限制，新生个体通过视觉挑选的觅食策略对最小的猎物大小具有最高的选择性。随着幼年杰克逊氏矶鲈的生长，最高偏好转向下一个更大的猎物大小。当杰克逊氏矶鲈成年时，主要的觅食方式从视觉挑选转变为相对不加区分的筛选行为。成年鱼觅食行为的转变伴随着对猎物大小总体偏好的下降；所捕食的大小几乎与其相对丰度成比例。成年侧条矶鲈保留了视觉挑选策略，并对最大类别的猎物具有最高的选择性。成年鱼在选择性模式上的这些差异不能用口裂限制来解释，因为这两个物种的成年个体都能摄取它们所能获得的最大猎物。这些结果支持了斯科特和默多克（1983年）的假说，即大小选择的定性模式在很大程度上取决于相对于捕食者能够有效获取的猎物大小范围。
