Physical calculations of resistance to water loss improve species range models: reply.
Physical calculations of resistance to water loss improve species range models: reply.
复制标题
抗水损失的物理计算改进了物种范围模型：回复。
作者：
E. Riddell;M. Sears
Christian等人（2017）提出了里德尔等人提出的方法和逻辑中的几个可能的缺陷。（2017），其中包括测量过程中蝾螈的潜在活动，琼脂模型腿的修剪，对经验数据的误解，琼脂模型的局限性，以及身体大小和皮肤失水阻力（ri）之间的关系。我们认为，这些批评是很容易解决的，在这里，我们加强了我们原来的主张，琼脂法测定耐失水是有缺陷的。在回应这些个别批评之前，我们开始对琼脂模型方法和确定抗失水性的一般方法进行更深入的批评，这种方法导致了边界层的生态和生理重要性的具体化。Christian等人还宣传了与琼脂模型方法的缺陷直接相关的用于估算边界层阻力（rb）值的既定物理过程的误导性信息。我们希望我们的回应能启发生理生态学家了解阻碍水分流失研究进展的障碍。涉及抗失水性测量的复杂性来自其生理和生物物理成分。总失水阻力（rT）是皮肤阻力（ri）（生理成分）和生物体周围空气边界层阻力（rb）（生物物理成分）的总和。在最近的一项研究中（里德尔等人，2017年），我们比较了两种用于分解总失水阻力的生理和生物物理成分的技术。我们比较了根据物理原理计算的rb估计值与使用焦点生物（陆生蝾螈）的琼脂复制品的经验方法。经验方法假定琼脂不具有ar i，因此，任何电阻测量都假定为rb。里德尔等人（2017）得出结论，由于rb的经验和理论估计值之间存在鲜明对比，并且违反了皮肤和边界层阻力的物理预期，因此琼脂法是一种估计边界层阻力的无效技术。这些结论受到了克里斯蒂安等人的审查。由于怀疑在方法和逻辑上的缺陷。在我们讨论他们的具体批评之前，我们必须确定Christian等人提出的边界层的错误概念，它忽略了生物物理学文献中的关键细节。边界层可以说是最动态的，因此是最复杂的，影响水分流失率的因素。边界层指的是物体周围的空气，物体和环境之间在边界层上发生热量或质量交换（Gates 1980）。影响边界层厚度的过程（以及它提供的对热和水通量的阻力）根据主要的物理条件而变化。边界层在所有条件下都受空气的粘度、物体的形状和方向以及物体的大小的影响，但气流的流速（或风速）与边界层有更动态的关系。流速决定了塑造边界层的主要力：气流力的惯性（即强迫对流）或动物与环境之间浓度梯度的浮力（即自由对流）。在强制对流过程中，流速沿生物体产生沿着的拖曳力，该拖曳力形成边界层，并且rb与气流的速度成正比且成反比（Gates 1980.
Christian et al.(2017) proposed several possible flaws in the methods and logic presented by Riddell et al.(2017) that included potential activity of salamanders during measurements, trimming of the agar model’s legs, misinterpretations of the empirical data, limitations on agar models, and the relationship between body size and skin resistance to water loss (ri). We argue that these criticisms are easily addressable, and here, we reinforce our original claim that the agar method for determination of resistance to water loss is flawed. Before responding to these individual critiques, we begin with a deeper criticism of the agar model method and general methodology for determining resistance to water loss that has resulted in the reification of the boundary layer’s ecological and physiological importance. Christian et al. also promoted misleading information on the established physical processes for estimating the value of the boundary layer resistance (rb) that relate directly to the flaws of the agar model method. We hope that our response enlightens physiological ecologists on the obstacles that impede the progress of water loss studies. The complications involving measurements of resistance to water loss arise from its physiological and biophysical components. The total resistance to water loss (rT) is the sum of the resistance of the skin (ri), the physiological component, and the boundary layer of air surrounding the organism (rb), the biophysical component. In a recent study (Riddell et al. 2017), we compared two techniques that are used to decompose the physiological and biophysical components of total resistance to water loss. We compared estimates of rb calculated from physical principles to an empirical method that used agar replicas of the focal organism, a terrestrial salamander. The empirical method assumes that agar does not have ar i, and therefore, any measurement of resistance is assumed to be the rb. Riddell et al.(2017) concluded that the agar method was an ineffective technique to estimate the boundary layer resistance due to the stark contrast between the empirical and theoretical estimates of rb and the violation of physical expectations for both skin and boundary layer resistance. These conclusions have come under scrutiny by Christian et al. due to suspected flaws in methods and logic. Before we address their specific criticisms, we must identify a false conception of the boundary layer promoted by Christian et al. that ignores critical details in the established literature of biophysics. The boundary layer is arguably the most dynamic, and thus complicated, factor that influences the rate of water loss. The boundary layer refers to the air surrounding an object over which the exchange of heat or mass occurs between the object and the environment (Gates 1980). The processes that influence the thickness of the boundary layer (and thus the resistance to heat and water flux that it provides) change depending upon the prevailing physical conditions. The boundary layer is influenced by the viscosity of the air, the shape and orientation of the object, and the size of the object under all conditions, but the flow rate of the air stream (or wind speed) has a more dynamic relationship with the boundary layer. The flow rate determines the primary force that shapes the boundary layer: inertia from the force of the airstream (ie, forced convection) or buoyancy from concentration gradients between the animal and the environment (ie, free convection). During forced convection, the flow rate produces a drag force along the organism that shapes the boundary layer, and rb is proportional to and inversely associated with the velocity of the airstream (Gates 1980 …