Table 2. Difference in ventral channel measured in Euclidean distances for pairs of co-occurring Niphargus species and their inferred ancestors.

species pair	Movile	Cave	Frasassi	Cave system
	Euclidean distance	ecological process	Euclidean distance	ecological process
extant	2.8166	competition (p = 0.002)	3.386	competition (p<0.0001)
ancestral-lower	0.9876	random (p = 0.171)	2.63	random (p = 0.07)
ancestral-mean	0.5494	filtering (p = 0.024)	2.69	random (p = 0.056)
ancestral-upper	0.4197	filtering (p = 0.007)	2.704	random (p = 0.055)

Species pair: upper, mean, lower—COMPARE provides estimates of ancestral states with standard errors. We calculated three estimates of ancestral states, as mean, lower (reconstructed value—standard error) and upper (mean + standard error) and repeated the analyses for all three values.

Ecological process: the putative process leading to either significant similarity or significant difference of coexisting species. The p value indicates the probability that species pair is more similar or different than expected when compared to pairs of species randomly drawn from the corresponding regional species pool.