ASSEMBLING ECOLOGICAL COMMUNITIES IN TIME AND SPACE

Ecological communities do not spring into existence overnight, but dev elop during the process we call assembly. As in other complex systems, random assemblies may generate surprising patterns. In previous model s, sequential invasion and extinction moved successive species mixes t oward a persistent one. Other species present in the pool could not in vade this persistent mix. Chance events early in the assembly produced persistent mixes of different compositions. Most model species surviv ed somewhere by belonging to one or more of these different persistent mixes. We show that with more rapid invasion, communities move throug h complex cycles of composition, where each species gets its turn. The se complementary views offer insights into the diversity of natural co mmunities. Importantly, they have practical implications for those att empting to restore diversity to damaged ecosystems.