在一個食物來源不集中,、不可預(yù)測的生境中找到食物的最好方式是什么？理論表明,，覓食的生物應(yīng)采取一種“Lévy-flight”搜索策略,，它是“隨機(jī)行走”的一個變異形式，在這種形式的行走中,，短距離的探索性蹦蹦跳跳與偶爾較長距離的行走相間,。但當(dāng)捕食者發(fā)現(xiàn)它們自己周圍有豐足的食物時，簡單的不規(guī)則運(yùn)動或“布朗”運(yùn)動就應(yīng)當(dāng)足夠了,。
事實(shí)證明,，野生動物中有關(guān)真正的“Lévy-flight”式覓食的明顯證據(jù)難以獲得，但是現(xiàn)在,，對包括鯊魚,、大馬林魚（槍魚）和金槍魚在內(nèi)的14個海洋捕食者物種構(gòu)成的一個大型數(shù)據(jù)集所做的一項(xiàng)分析證明了這一點(diǎn)。電子標(biāo)記顯示,，當(dāng)在生產(chǎn)力較低,、獵物稀少的水域游動時，魚類采取Lévy行為,；而在生產(chǎn)力較高的生活環(huán)境中時,，它們則采用“布朗”運(yùn)動方式。（生物谷Bioon.net）
生物谷推薦原文出處：
Nature doi:10.1038/nature09116
Environmental context explains Lévy and Brownian movement patterns of marine predators
Nicolas E. Humphries,Nuno Queiroz,Jennifer R. M. Dyer,Nicolas G. Pade,Michael K. Musyl,Kurt M. Schaefer,Daniel W. Fuller,Juerg M. Brunnschweiler,Thomas K. Doyle,Jonathan D. R. Houghton,Graeme C. Hays,Catherine S. Jones,Leslie R. Noble,Victoria J. Wearmouth,Emily J. Southall& David W. Sims
An optimal search theory, the so-called Lévy-flight foraging hypothesis1, predicts that predators should adopt search strategies known as Lévy flights where prey is sparse and distributed unpredictably, but that Brownian movement is sufficiently efficient for locating abundant prey2, 3, 4. Empirical studies have generated controversy because the accuracy of statistical methods that have been used to identify Lévy behaviour has recently been questioned5, 6. Consequently, whether foragers exhibit Lévy flights in the wild remains unclear. Crucially, moreover, it has not been tested whether observed movement patterns across natural landscapes having different expected resource distributions conform to the theory’s central predictions. Here we use maximum-likelihood methods to test for Lévy patterns in relation to environmental gradients in the largest animal movement data set assembled for this purpose. Strong support was found for Lévy search patterns across 14 species of open-ocean predatory fish (sharks, tuna, billfish and ocean sunfish), with some individuals switching between Lévy and Brownian movement as they traversed different habitat types. We tested the spatial occurrence of these two principal patterns and found Lévy behaviour to be associated with less productive waters (sparser prey) and Brownian movements to be associated with productive shelf or convergence-front habitats (abundant prey). These results are consistent with the Lévy-flight foraging hypothesis1, 7, supporting the contention8, 9 that organism search strategies naturally evolved in such a way that they exploit optimal Lévy patterns.
