Fig. 9
From: Semi-permeable species boundaries in Iberian barbels (Barbus and Luciobarbus, Cyprinidae)
Relationship between levels of introgression and genetic divergence between hybridizing species pairs. A negative correlation between proportion of introgressed alleles and genetic divergence between species is observed, indicating a decrease in gene flow with increasing genetic differentiation. Species pairs in increasing order of genetic divergence based on mitochondrial DNA (from [26]): L. bocagei–L. comizo, L. comizo–L. sclateri, L. microcephalus–L. sclateri, L. comizo–L. microcephalus