Palmer Todd M
Department of Zoology, University of Wisconsin-Madison, Birge Hall, 430 Lincoln Drive, 53706, Madison, WI, USA.
Oecologia. 1995 Dec;104(4):476-486. doi: 10.1007/BF00341345.
Environmental heterogeneity can affect the behavior of organisms, but the consequences of patchiness for organismal energetics (e.g., growth, fitness) are not well understood. This study demonstrates that spatial heterogeneity can affect the growth of aquatic stream insects in laboratory streams, and reveals the behavioral mechanisms for these effects. In a 2×2 factorial design, I experimentally manipulated resource distribution (homogeneous vs. patchy, with the same overall resource levels) and current velocity (fast vs. slow) to investigate the direct and interactive effects of these factors on the drift behavior and growth of two mobile stream grazers, the mayflies Baetis bicaudatis and Epeorus deceptivus. B. bicaudatis nymphs grew larger in environments with homogeneously distributed resources than in patchy environments, and both species grew larger in fast than slow current environments. Patterns of drift behavior over the course of the study corresponded to observed differences in growth. Both species grew to larger body size in treatments where they drifted more successfully among substrates (fast-current treatments) and where they entered the drift less frequently (fast current for both species, and homogeneous treatments for B. bicaudatis). Overall, these results demonstrate that patchiness can significantly influence both the behavior of aquatic insects and the size to which these insects grow. In the light of previously published relationships between nymphal mayfly body mass and fecundity, these results suggest that patchiness in streams may have important consequences for mayfly populations.
环境异质性会影响生物体的行为，但斑块性对生物体能量学（如生长、适合度）的影响尚未得到充分理解。本研究表明，空间异质性会影响实验室溪流中水生昆虫的生长，并揭示了这些影响的行为机制。在一个2×2析因设计中，我通过实验操纵资源分布（均匀分布与斑块状分布，总体资源水平相同）和水流速度（快与慢），以研究这些因素对两种游动性溪流食草动物——两尾蜉蝣（Baetis bicaudatis）和迷惑蜉蝣（Epeorus deceptivus）的漂移行为和生长的直接和交互影响。两尾蜉蝣若虫在资源均匀分布的环境中比在斑块状环境中长得更大，并且两个物种在水流快的环境中比在水流慢的环境中长得更大。在研究过程中的漂移行为模式与观察到的生长差异相对应。在它们能更成功地在基质间漂移的处理中（水流快的处理）以及它们较少进入漂移状态的处理中（两个物种都是水流快的处理，两尾蜉蝣是资源均匀分布的处理），两个物种都生长到更大的体型。总体而言，这些结果表明斑块性会显著影响水生昆虫的行为以及这些昆虫生长到的体型大小。鉴于之前发表的蜉蝣若虫体重与繁殖力之间的关系，这些结果表明溪流中的斑块性可能对蜉蝣种群有重要影响。
