Habitat filtering, not dispersal limitation, drives ant and termite community assembly along a tropical forest regeneration gradient

Nina Grella, David A. Donoso, Jörg Müller, Ana Falconí-López, Annika Busse, Marcel Püls, Dominik Rabl, Heike Feldhaar

Regenerating forests comprise a significant proportion of forest ecosystems in the tropics. However, species assembly mechanisms after anthropogenic disturbances are still poorly understood. It has been shown that locally established ant communities clearly assemble along gradients of forest regeneration. However, it is unclear if this is determined by dispersal limitation or habitat filtering (abiotic and biotic conditions). To disentangle the two processes for ant and termite communities we compared community composition of dispersing and sessile life stages in the Chocó lowland tropical forest in Ecuador. Our chronosequence comprises a regeneration gradient ranging from agricultural land to regenerating forests to old-growth forests. We show that assemblages of winged reproductives (alates) of both taxa do not differ significantly between forest regeneration stages, but communities were more similar in spatially closer plots. Worker ant communities originating from established colonies were driven by forest regeneration age and elevation. Termite worker communities were driven by elevation and plot location. These results suggest that alates of both taxa have the potential to reach and colonize forests of all regeneration ages and elevations, but not all species establish colonies or persist in all forest regeneration or elevational stages. For ants we conclude that the distribution of colonies is more affected by habitat filters associated with elevation and the forest structure along the chronosequence. For termites we conclude that the distribution of colonies is more affected by habitat filtering associated with elevation and by possible intraspecific interactions, as their communities were more dissimilar in spatially closer plots.