The role of head-shape and trophic variation in the diversification of the genus Herichthys in sympatry and allopatry

" In the present study we evaluate the putative cases of sympatric speciation in the genus Herichthys by studying the variation of the head shape using principal component analysis, phylomorphospace and reconstructions of the ancestral states of feeding preferences. Herichthys includes both allopatric as well as sympatric sister-species, as well as sympatric unrelated species and offers thus great potential for evolutionary studies of putatively sympatric speciation. Herichthys is the northernmost group of cichlids in America and one of the most ecologically disparate genera within Middle American cichlids. Fifteen anatomical points were recorded on the heads of 293 specimens of the 11 species recognized within the genus. The results showed that in spite of having wide variation in consumed diets, most species of Herichthys are close in morphospace. However, morphological variation was great among the two pairs of sympatric sister species in agreement with the suggested sympatric model of speciation "