Uniting bands include synapomorphies, autapomorphies in the excluded cluster, and bands shared due to gene flow between clusters. The observed six to seven percent of sharing might well represent autapomorphic losses of bands within the epigean cluster. On the other hand, the high proportions of bands shared between both the northern and southern cave populations and the epigean forms cannot have a phylogenetic cause. Instead, we suggest that the high proportions of uniting bands reflect gene flow into the cave populations. We stress that gene flow into the cave populations does not necessarily prove that surface genes move at any significant rate into the underlying aquifer population of hypogean fish.
First lines list numbers as a fraction of the total bands in the united clusters.
Mitchell et al. We also obtained DNA sequence data from a fragment of the PAX6 gene. These data are preliminary results of a larger ongoing sequencing effort and are reported here only as the observed proportion of nucleotide substitutions. PAX6 mutations cause anirrid ia in humans and small eyes in mice. Thus, they have no functional significance for blindness in these fish, but are useful for dating the divergence of the cave and surface forms.