| dc.description |
The searching trajectories of different animals can be described
with a broad class of flight length (lj) distributions with P(lj)=lj-u. Theoretical studies have shown that changes in these distributions
(i.e., different u values) are key to optimizing the long-term
encounter statistics under certain searcher–resource scenarios. In
particular, they predict the advantage of Lévy searching ( u~2)
over Brownian motion (u>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 threedimensional
environment, a stronger helical component combined
with a Lévy 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. |
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