How good are epigeic earthworms at dispersing? An investigation to compare epigeic to endogeic and anecic groups

International audienceDispersal capacities can strongly determine an individual’s ability to respond to changing 4 environmental conditions, which would consequently influence the structure of natural 5 communities. Nonetheless, we know little about the dispersal behaviour of soil organisms, 6 despite some of these organisms, such as earthworms, have key roles in ecosystem 7 functioning (e.g. organic matter decomposition). We expect that species exposed to frequent 8 environmental changes would benefit from the capacity to escape from adverse environmental 9 conditions and to disperse to settle in a more suitable habitat. In earthworms, we expect the 10 epigeic group, which lives at or close to the soil surface, to have evolved higher dispersal 11 capacities than the two other functional groups – anecic and endogeic, which live deeper in 12 the soil. In this study, we investigated dispersal and diffusion behaviour of three species of 13 epigeic earthworms (i.e. Eisenia fetida, Eisenia andrei and Lumbricus rubellus) and compared 14 these behaviours with those of anecic and endogeic earthworms, whose behaviour has been 15 previously measured through similar experiments. In accordance with our hypothesis, our 16 study shows that dispersal behaviour of epigeic earthworms depends on habitat quality and 17 population density, but that those responses vary among species and that it differs only to a 18 limited extent from behaviour of anecic and endogeic earthworms