Habitat isolation reduces intra- and interspecific biodiversity and stability

Fragmentation is predicted to reduce biodiversity and stability by increasing habitat isolation and impeding dispersal among patches. These effects may manifest at both the interspecific and intraspecific levels, yet few studies have simultaneously explored dispersal effects across levels of organization. We used field mesocosm experiments to examine how habitat isolation (in the form of dispersal rate) alters inter- and intraspecific stability and diversity in local zooplankton communities. We observed effects of increasing dispersal rate at both the intra- and interspecific levels. Increasing dispersal increased local species diversity and reduced mean temporal variability of populations. At the intraspecific level, Daphnia pulex clonal diversity was enhanced by dispersal and mean temporal variability of clone abundances through time was reduced.

生境破碎化（habitat fragmentation）被认为可通过加剧生境隔离、阻碍斑块间扩散，降低生物多样性与群落稳定性。此类效应可同时表现于种间与种内层面，但目前鲜有研究同时探索扩散效应对不同组织层次的影响。本研究借助野外中型实验生态系统（field mesocosm）实验，探究以扩散速率表征的生境隔离如何改变局部浮游动物群落的种间、种内稳定性与多样性。我们在种间与种内层面均观测到了扩散速率提升带来的效应：提升扩散速率可增加局部物种多样性，并降低种群的平均时间变异性。在种内层面，蚤状溞（Daphnia pulex）的克隆多样性因扩散作用得到提升，克隆丰度随时间变化的平均变异性也随之降低。