Simulation of spatial movement that potentially maximizes assessment, presence, and defence in territorial and home-ranging animals, with special reference to territorial sex-changing fishes

摘要

Question: Are there territory sizes, shapes, and movement rules that animals can use to maximize their presence for territorial and reproductive purposes? Features of the model: Individual-oriented simulation model of a focal male, a female (his mate), and six other males in adjacent territories. Simulation variables were territory size and aspect (length-to-width ratio), velocity, step size, and potential movement angle. Each simulation represented 10,000 s of real time, and simulations were repeated until convergence on maximum mean encounter rates (MER) of a focal male with the female and other males was reached. Ranges of variables: Simulations consisted of three velocities (0.05, 0.1, and 0.2 m-s1), three step sizes (time between movement decisions of 0.5, 1, and 2 s), 18 movement angles (20°, 40°, 60°, . . . 360°), four territory sizes (1, 10, 100, 400 m~2), and four territory aspects (1,2, 4, 8). Conclusions: Random movement maximizes MER with a female only in small territories (e.g. 1 m~2), but use of a simple correlated random walk strategy ('trajectory-swimming' in fishes) maximizes MER with both females and males for other territories, regardless of aspect. This form of movement also minimizes variability of MER; specifically, it gives a more reliable signal, or 'truth in advertising' of territoriality.