Dissertation Research: Habitat Partitioning by Notonectids: Temporal Patterns and the Role of Spatial Complexity

9902177 Gilbert公会内的捕食者是潜在的竞争对手，也是相互捕食性的，尽管它经常发生，但很少被模型预测。减少冲突的一种机制是栖息地的空间分割。在一个小而浅的池塘里观察到了这样的地带性分布，有四个非脊椎动物物种--贪婪的昆虫捕食者，它们共享资源，随时相互觅食。这种划分可能会减少冲突，但这些模式表现出季节性和间歇性的变化，可能会实质上危及或加强共存。在本论文的研究中，实地调查将定量地证实本文提出的初步观察结果。导致空间分割和时间变化的机制将在实验微观世界中进行研究。幼体在季节中期的分布变化可能是对成体捕食者减少的反应，使幼体能够在资源丰富的栖息地完成发育。相反，物种分布的昼夜变化增加了夜间重叠，从而增加了冲突的可能性。对野外采集的夜蛾的昼夜食性进行比较，使用肠道内容物电泳法，以确定公会内捕食量是否如预期的那样在夜间增加。此外，还提出了一种新的水平迁徙假说：对于视觉和机械接收的捕食者来说，空间复杂和开放的栖息地在夜间的盈利能力是相反的。

9902177GilbertCoexistence of intraguild predators, potential competitors that are also mutually predaceous, is rarely predicted by models despite its commonplace occurrence. One mechanism by which conflict may be minimized is spatial partitioning of habitat. Such zonation has been observed in a small shallow pond with four notonectid species - voracious insect predators which share resources and readily feed on each other. Conflict may be reduced by this partitioning, but these patterns exhibit seasonal and diel shifts in ways that could substantially endanger or enhance coexistence. In this dissertation research, field study will quantitatively confirm the preliminary observations presented here. Mechanisms leading to spatial partitioning and temporal changes will be investigated in experimental microcosms. Mid-season distributional shifts of juveniles may be a response to a decline in adult predators, allowing juveniles to complete development in a high-resource habitat. Conversely, diel shifts in species distribution increase potential for conflict by increasing nocturnal overlap. Diurnal and nocturnal diet of field-collected notonectids will be compared, using electrophoretic gut content analysis, to determine whether intraguild predation increases at night as expected. In addition, a new hypothesis for diel horizontal migration is proposed: profitability of spatially complex and open habitat is reversed at night for predators using both vision and mechanoreception.