We investigate a modified spatial stochastic Lotka-Volterra formulation of the rock-paper-scissors model using off-lattice stochastic simulations. In this model one of the species moves preferentially in a specific direction —the level of preference being controlled by a noise strength parameter ( and corresponding to total preference and no preference, respectively)— while the other two species have no preferred direction of motion. We study the behaviour of the system starting from random initial conditions, showing that the species with asymmetric mobility has always an advantage over its predator. We also determine the optimal value of the noise strength parameter which gives the maximum advantage to that species. Finally, we find that the critical number of individuals, below which the probability of extinction becomes significant, decreases as the noise level increases, thus showing that the addition of a preferred mobility direction studied in the present letter does not favour coexistence.

我们研究了使用非晶格随机模拟的修改后的空间随机Lotka-Volterra剪刀石头布模型的公式。在此模型中，一个物种优先沿特定方向移动-优先级别由噪声强度参数（和分别对应于总偏好和无偏好），而其他两个物种没有偏好的运动方向。我们从随机初始条件开始研究系统的行为，表明具有非对称迁移率的物种始终比其掠食者更具优势。我们还确定了噪声强度参数的最佳值，该值为该种类提供了最大的优势。最后，我们发现，随着噪声水平的提高，绝种个体的临界数量（在其之下绝种的可能性变得显着）降低了，因此表明，在本文中研究的优选迁移方向的添加不利于共存。