Long-term species coexistence in a metacommunity is compatible with niche differences and strong competition at a local scale
Maxime Dubart, Patrice David, Frida Ben-Ami, Christoph R. Haag, Peter D. Fields, V. Ilmari Pajunen & Dieter Ebert
In fragmented landscapes, strongly competing taxa often paradoxically coexist. Coexistence may be facilitated by species-specific habitat preferences, however describing ecological niche in a metacommunity context is not straightforward. A 30-year study of a Daphnia rockpool metacommunity here illustrates how state-space modelling can jointly describe niches, species interactions and distance effects on species colonization and extinction rates. Simulations are used to tell how each process affects coexistence and constrains species distributions. We notably find strong and species-specific influences of season, habitat variables, and interspecific interactions on local extinction rates. Species differences in fundamental and realized niches are present but largely overlap, and they play a limited role in coexistence. Rather, competitive exclusion within sites does not scale up to regional exclusion because it is strongly seasonal, and opportunities of species co-occurrence are limited by rapid extinction-colonization dynamics. Our study provides a way to challenge the paradox of metacommunity stability despite strong competition.