Animals use different modes of movement at different times, in different locations, and on different scales. Incorporating such context dependence in mathematical models represents a substantial increase in complexity, but creates an opportunity to more fully integrate key biological features. Here, we consider the spatial dynamics of a population of foragers with two subunits. In one subunit, foragers move via diffusion (random search) whereas in the other, foragers move via advection (gradient-following search). Foragers switch back and forth between the subunits as functions of their spatial context (i.e., depending on whether they are inside or outside of a patch, or depending on whether or not they can detect a gradient in resource density). We consider a one-dimensional binary landscape of resource patches and non-habitat and gauge success in terms of how well the mobile foragers overlap with the distribution of resources. Actively switching between dispersal modes can sometimes greatly enhance this spatial overlap relative to the spatial overlap possible when foragers merely blend advection and diffusion modes at all times. Switching between movement modes is most beneficial when organism’s gradient-following abilities are weak compared to its overall capacity for movement, but switching can actually be quite detrimental for organisms that can rapidly follow resource gradients. An organism’s perceptual range plays a critical role in determining the conditions under which switching movement modes benefits versus disadvantages foragers as they seek out resources.

中文翻译：

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通过在扩散和对流之间切换来改善觅食：取决于空间背景的运动带来的好处

动物在不同的时间，不同的位置和规模上使用不同的运动方式。在数学模型中纳入这种上下文相关性会大大增加复杂性，但会为更全面地整合关键生物学特征创造机会。在这里，我们考虑具有两个亚基的觅食种群的空间动力学。在一个子单元中，觅食者通过扩散移动（随机搜索），而在另一个子单元中，觅食者通过对流移动（梯度跟随搜索）。觅食者根据其空间上下文的功能在子单元之间来回切换（即，取决于它们是位于补丁内部还是外部，或者取决于它们是否可以检测资源密度的梯度）。我们考虑资源补丁和非栖息地的一维二元格局，并根据移动觅食者与资源分配的重叠程度来衡量成功与否。相对于当觅食者一直都在混合对流和扩散模式时可能出现的空间重叠，主动地在分散模式之间切换有时会大大增强这种空间重叠。与生物体的整体运动能力相比，当生物体的梯度跟随能力较弱时，在运动模式之间进行切换是最有益的，但是，这种切换实际上会对可能迅速跟随资源梯度的生物体造成极大的损害。生物体的知觉范围在确定觅食者在寻找资源时改变运动方式有利与不利觅食的条件之间起着至关重要的作用。