Abstract
Turnover of species composition through time is frequently observed in nature. Often explained by changes in abiotic conditions or regional species pools, compositional turnover is employed as an indicator of external stress in natural ecosystems. Theoretically, the possibility of turnover driven by intrinsic ecological dynamics—species interactions, dispersal—is also known, but what role such autonomous turnover plays in nature remains unclear. Expanding the boundaries of metacommunity modelling, we show that in large metacommunities immigration pressure from neighbouring locales robustly drives continuous turnover in local composition—without environmental change or regional invasions. That ecological communities may turn over autonomously challenges assumptions implicit in assessment and management tools, and suggests that natural compositional change should be incorporated in ecological status assessments based on ancestral baselines.
One Sentence Summary Biodiversity change previously attributed to external drivers is explained as a robust, naturally occurring phenomenon.
Competing Interest Statement
The authors have declared no competing interest.