Demographic stochasticity and resource autocorrelation control biological invasions in heterogeneous landscapes

Mounting theoretical evidence suggests that demographic stochasticity, environmental heterogeneity and biased movement of organisms individually affect the dynamics of biological invasions and range expansions. Studies of species spread in heterogeneous landscapes have traditionally characterized invasion velocities as functions of the mean resource density throughout the landscape, thus neglecting higher-order moments of the spatial resource distribution. Here, we show theoretically that different spatial arrangements of resources lead to different spread velocities even if the mean resource density throughout the landscape is kept constant. Specifically, we find that increasing the resource autocorrelation length causes a reduction in the speed of species spread. The model shows that demographic stochasticity plays a key role in the slowdown, which is strengthened when individuals can actively move towards resources. We then experimentally corroborated the theoretically predicted redu...

日益增多的理论证据表明，种群统计随机性（demographic stochasticity）、环境异质性（environmental heterogeneity）以及生物体的偏向性移动，会分别对生物入侵和分布范围扩张的动态过程产生影响。针对异质性景观中物种扩散的传统研究，通常将入侵速度表征为整个景观内平均资源密度的函数，因而忽略了空间资源分布的高阶矩特征。本研究从理论层面证明，即便整个景观的平均资源密度保持恒定，不同的资源空间排布模式也会导致各异的物种扩散速度。具体而言，我们发现增大资源自相关长度（resource autocorrelation length）会降低物种的扩散速率。模型结果显示，种群统计随机性是引发扩散速率减缓的关键因素，而当生物体能够主动趋向资源移动时，这种减缓效应会得到进一步强化。随后我们通过实验对理论预测的扩散速率减缓效应进行了佐证……