Hoyle Martin, Cresswell James E
School of Biosciences, University of Exeter, Exeter EX4 4PS, UK.
J Theor Biol. 2007 Sep 7;248(1):154-63. doi: 10.1016/j.jtbi.2007.04.022. Epub 2007 May 1.
We present a spatially implicit analytical model of forager movement, designed to address a simple scenario common in nature. We assume minimal depression of patch resources, and discrete foraging bouts, during which foragers fill to capacity. The model is particularly suitable for foragers that search systematically, foragers that deplete resources in a patch only incrementally, and for sit-and-wait foragers, where harvesting does not affect the rate of arrival of forage. Drawing on the theory of job search from microeconomics, we estimate the expected number of patches visited as a function of just two variables: the coefficient of variation of the rate of energy gain among patches, and the ratio of the expected time exploiting a randomly chosen patch and the expected time travelling between patches. We then consider the forager as a pollinator and apply our model to estimate gene flow. Under model assumptions, an upper bound for animal-mediated gene flow between natural plant populations is approximately proportional to the probability that the animal rejects a plant population. In addition, an upper bound for animal-mediated gene flow in any animal-pollinated agricultural crop from a genetically modified (GM) to a non-GM field is approximately proportional to the proportion of fields that are GM and the probability that the animal rejects a field.
我们提出了一种觅食者运动的空间隐式分析模型，旨在解决自然界中常见的一种简单情形。我们假设斑块资源的消耗极小，且觅食者进行离散的觅食回合，在此期间觅食者会吃饱。该模型特别适用于系统搜索的觅食者、仅逐渐消耗斑块资源的觅食者以及坐等型觅食者，在这些情形下收获行为不会影响觅食的到达率。借鉴微观经济学中的求职理论，我们仅依据两个变量来估计预期访问的斑块数量：斑块间能量获取率的变异系数，以及在随机选择的斑块上预期利用时间与斑块间预期旅行时间的比率。然后，我们将觅食者视为传粉者，并应用我们的模型来估计基因流动。在模型假设下，自然植物种群之间动物介导的基因流动上限大约与动物拒绝一个植物种群的概率成正比。此外，在任何动物传粉的农作物中，从转基因田地到非转基因田地的动物介导的基因流动上限大约与转基因田地的比例以及动物拒绝一块田地的概率成正比。
