Figure 6

Simplified representation of three idealised scenarios of subterranean colonization leading to an extant monophyletic hypogean lineage (see Discussion ). Different combinations of the three, in all possible degrees, can be found among the subterranean Trechini from the Alps. a: Three independent subterranean colonizations from a widespread epigean ancestor. b: Same as (a), but preceded by speciation of the epigean ancestor. The three resulting epigean species colonize independently the subterranean medium. c: Single subterranean colonization, with subsequent dispersal and diversification of the hypogean species.