Data from: Evidence for an optimal level of connectivity for establishment and colonization

Dispersal is usually associated with the spread of invasive species, but it also has two opposing effects, one decreasing and the other increasing the probability of establishment. Indeed, dispersal both slows population growth at the site of introduction and increases the likelihood of surrounding habitat being colonised. The connectivity of the introduction site is likely to affect dispersal, and, thus, establishment, according to the dispersal behaviour of individuals. Using individual-based models and microcosm experiments on minute wasps, we demonstrated the existence of a hump-shaped relationship between connectivity and establishment in situations in which individual dispersal resembled a diffusion process. These results suggest that there is an optimal level of connectivity for the establishment of introduced populations locally at the site of introduction, and regionally over the whole landscape.

扩散通常与入侵物种的传播过程相关联，但该过程同时存在两种截然相反的效应：其一可降低种群定殖概率，其二则会提升该概率。事实上，扩散既会减缓引入位点处的种群增长速率，也会提升周边栖息地被成功定殖的可能性。结合个体的扩散行为来看，引入位点的连通性极有可能对扩散过程乃至定殖结果产生影响。本研究依托基于个体的模型（individual-based models）与针对小型寄生蜂（minute wasps）的微宇宙实验（microcosm experiments），证实了在个体扩散符合扩散过程的场景下，连通性与定殖成功率之间存在驼峰型关联。上述结果表明，无论是在引入位点的局部尺度，还是覆盖整个景观的区域尺度，引入种群的定殖均存在一个最优连通性水平。