Species turnover through time: colonization and extinction dynamics across metacommunities

Island biogeography and metacommunity theory often use equilibrium assumptions to predict local diversity, yet non-equilibrium dynamics are common in nature. In non-equilibrium communities, local diversity fluctuates through time as the relative importance of colonization and extirpation change. Here, we test the prevalence and causes of non-equilibrium dynamics in metacommunities of mites associated with rubber trees distributed over large spatial (>1000 km) and temporal (> 30-60 generations) scales in Brazil. We measured colonization and extirpation rates to test species turnover and non-equilibrium dynamics over a growing season. Mite metacommunities exhibited non-equilibrium dynamics for most months of the year, and these dynamics tracked climatic conditions. Monthly shifts in temperature of more than one degree Celsius resulted in non-equilibrium dynamics, as did mean temperatures outside of two critical ranges. Non-equilibrium dynamics were caused by a change in colonization with temperature change, and changes in both colonization and extirpation with absolute temperature. Species turnover showed different trends; high relative humidity increased both colonization and extirpation rates, increasing turnover but not non-equilibrium dynamics. Our study illustrates that testing non-equilibrium dynamics can provide new insights into the drivers of colonization, extinction and diversity fluctuations in metacommunities.