In problems of ecological dynamics involving bistability (two disjoint attractors A 1 and A 2), we present (with various examples) a natural ecological mechanism allowing the transfer from the attraction basin of A 1 to the other basin, so allowing to reach A 2 from any initial configuration. The mechanism involve an extra species which changes the dimension of the phase space and the topology of the attraction basins. The extra species disappear in a natural way, so that this mechanism keeps some relation with apoptosis, but is different of it.