Beating the Odds in the Aerial Lottery: Passive Dispersers Select Conditions at Takeoff That Maximize Their Expected Fitness on Landing

Passive airborne dispersal, in which the direction and distance of travel are determined by air movement, affects propagules and pollens, as well as mites, spiders, and small insect larvae. The takeoff or launch phase is, however, largely controlled, and many organisms become airborne only under particular weather conditions at takeoff, when the distribution of distances traveled will have a -3/2 power-law tail, a hallmark of Lévy flights. Here these movement patterns are shown to maximize the likelihood of dispersing to the nearest unoccupied site, thereby maximizing expected fitness on landing.