Helical Levy walks:: Adjusting searching statistics to resource availability in microzooplankton
Helical Levy walks:: Adjusting searching statistics to resource availability in microzooplankton
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DOI：
10.1073/pnas.2137243100
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发表时间：
2003-10-28
影响因子：
11.1
通讯作者：
Catalan, J
中科院分区：
文献类型：
--
作者：
Bartumeus, F;Peters, F;Catalan, J
不同动物的搜索轨迹可以用一大类飞行长度 (I-j) 分布来描述，其中 P(I-j) = l(i)(-mu)。理论研究表明，这些分布的变化（即不同的 mu 值）是在某些搜索者资源场景下优化长期遭遇统计的关键。特别是，他们预测在低猎物密度场景下，Levy 搜索（mu 近似于 2）相对于布朗运动（mu 大于或等于 3）的优势。在这里，我们提出了实验证据，预测捕食者行走的飞行时间分布的最佳变化是响应其移动猎物的逐渐密度变化的。当猎物（红单胞菌）数量减少时，甲藻尖藻的飞行时间从指数分布转变为反平方幂律分布。与此同时，短期螺旋路径的幅度和频率增加。讨论了这些搜索行为变化所涉及的具体生物学机制。我们建议，在三维环境中，更强的螺旋成分与 Levy 步行搜索策略相结合可以提高捕食者的遭遇率。尽管生物体的生物学细节存在差异，但我们的结果支持了最优搜索过程中统计定律的普遍性这一想法。
The searching trajectories of different animals can be described with a broad class of flight length (I-j) distributions with P(I-j) = l(i)(-mu). Theoretical studies have shown that changes in these distributions (i.e., different mu values) are key to optimizing the long-term encounter statistics under certain searcher-resource scenarios. In particular, they predict the advantage of Levy searching (mu approximate to 2) over Brownian motion (mu greater than or equal to 3) for low-prey-density scenarios. Here, we present experimental evidence of predicted optimal changes in the flight-time distribution of a predator's walk in response to gradual density changes of its moving prey. Flight times of the dinoflagellate Oxyrrhis marina switched from an exponential to an inverse square power-law distribution when the prey (Rhodomonas sp.) decreased in abundance. Concomitantly, amplitude and frequency of the short-term helical path increased. The specific biological mechanisms involved in these searching behavioral changes are discussed. We suggest that, in a three-dimensional environment, a stronger helical component combined with a Levy walk searching strategy enhances predator's encounter rates. Our results support the idea of universality of the statistical laws in optimal searching processes despite variations in the biological details of the organisms.