THE ADAPTATION VALUE OF REPRODUCTIVE STRATEGY AND MODE IN 3 EPIGEOUS EARTHWORM SPECIES

Three resource exploitation modes of crushed household refuse on heathland, are associated with three earthworm colonizer types. The first colonizer type fits with the unstable environments species selection (Dendrobaena rubida tenuis, Eisen, 1874; Eisenia fetida, Savigny, 1826; Eisenia andrei, Bouche, 1972). The mechanisms analysis dealt with the demographic parameters parameters comparison (generation time, fecundity and natality). This analysis is in relation to the reproductive mode (Dendrobaena rubida tenuis parthenogenetic; E. fetida and E. andrei amphigonic). Experimental approach of the anatomy and fife history was carried out on D.r. tenuis (by isolation or by group of five individuals). The descendant's demographic profile of the uniparental strain was studied on three generations. E. fetida and E. andrei populations were studied in the same way to have amphigonic reproduction reference models. Life history parameters of mated and unmated D.r. tenuis are similar. E. andrei and E. fetida produce cocoons only after mating. E. andrei showed the capacity to preserve the viability of sperm from the partner for at least 54 weeks after the last insemination. The fecundity is lower for mated worms E. andrei. However, these two groups (D.r. tenuis and Eisenia sp.) have developed two different reproductive strategies, but which give similar capacities of colonization.