NatWi - Gesine Pufal

Adverse environmental conditions increase directed seed dispersal by slugs

Generalist granivores might be more influential for plant community assembly than previously thought. Some generalist granivores, such as slugs, are also efficient endozoochorous seed dispersers, adding even more complexity to their role. We have some knowledge about functional traits that affect endozoochory, but there is no information on how seed dispersal patterns are affected by slug movement under different environmental conditions. Using microcosms and time-lapse videos, we tested whether dry or wet conditions in a slug - seed system affect slug movement, thus influencing seed encounter and dispersal locations. Higher slug movement increased the chance of seed encounter and the majority of ingested seeds were excreted intact in a clustered pattern around the slugs’ shelter. Dry conditions increased homing behavior in slugs and clustering was therefore significantly more pronounced. With predicted drier summers in continental Europe, directed dispersal to moist microhabitats might increase with unknown implications for community assembly.