Computational Geo-Ecology, Institute for Biodiversity and Ecosystem Dynamics, Department of Science, University of Amsterdam, P.O. Box 94248, 1090 GE Amsterdam, The Netherlands.
J Theor Biol. 2012 Sep 7;308:56-67. doi: 10.1016/j.jtbi.2012.05.026. Epub 2012 Jun 6.
The impact that flows of air and water have on organisms moving through these environments has received a great deal of attention in theoretical and empirical studies. There are many behavioral strategies that animals can adopt to interact with these flows, and by assuming one of these strategies a researcher can quantify the instantaneous assistance an animal derives from a particular flow. Calculating flow-assistance in this way can provide an elegant simplification of a multivariate problem to a univariate one and has many potential uses; however, the resultant flow-assistance values are inseparably linked to the specific behavioral strategy assumed. We expect that flow-assistance may differ considerably depending on the behavioral strategy assumed and the accuracy of the assumptions associated with that strategy. Further, we expect that the magnitude of these differences may depend on the specific flow conditions. We describe equations to quantify flow-assistance of increasing complexity (i.e. more assumptions), focusing on the behavioral strategies assumed by each. We illustrate differences in suggested flow-assistance between these equations and calculate the sensitivity of each equation to uncertainty in its particular assumptions for a range of theoretical flow conditions. We then simulate trajectories that occur if an animal behaves according to the assumptions inherent in these equations. We find large differences in flow-assistance between the equations, particularly with increasing lateral flow and increasingly supportive axial flow. We find that the behavioral strategy assumed is generally more influential on the perception of flow-assistance than a small amount of uncertainty in the specification of an animal's speed (i.e. <5 ms(-1)) or preferred direction of movement (i.e. <10°). Using simulated trajectories, we show that differences between flow-assistance equations can accumulate over time and distance. The appropriateness and potential biases of an equation to quantify flow-assistance, and the behavioral assumptions the equation implies, must be considered in the context of the system being studied, particularly when interpreting results. Thus, we offer this framework for researchers to evaluate the suitability of a particular flow-assistance equation and assess the implications of its use.
空气和水流对生物在这些环境中的运动的影响，在理论和实证研究中受到了广泛关注。动物可以采用许多行为策略来与这些流相互作用，通过采用其中一种策略，研究人员可以量化动物从特定流中获得的瞬时辅助力。以这种方式计算流辅助力可以将一个多变量问题简化为一个单变量问题，并且具有许多潜在用途；然而，所得的流辅助力值与所假设的特定行为策略不可分割地联系在一起。我们预计，流辅助力可能会因所假设的行为策略以及与该策略相关的假设的准确性而有很大差异。此外，我们预计这些差异的幅度可能取决于特定的流条件。我们描述了越来越复杂（即更多假设）的量化流辅助力的方程，重点介绍了每个方程所假设的行为策略。我们说明了这些方程之间建议的流辅助力之间的差异，并计算了每个方程对其特定假设的不确定性的敏感性，这些假设针对一系列理论流条件。然后，我们模拟了如果动物根据这些方程所固有的假设行为，则会发生的轨迹。我们发现，方程之间的流辅助力差异很大，特别是随着横向流的增加和轴向流的支持增加。我们发现，所假设的行为策略通常比动物速度（即<5 ms(-1))或首选运动方向（即<10°）的指定中的少量不确定性对流辅助力的感知更有影响。通过模拟轨迹，我们表明，流辅助力方程之间的差异会随着时间和距离的累积而累积。在研究的系统背景下，必须考虑量化流辅助力的方程的适当性和潜在偏差，以及方程所隐含的行为假设，特别是在解释结果时。因此，我们提供了这个框架，供研究人员评估特定流辅助力方程的适用性，并评估其使用的影响。
