Evolutionary body shape diversification of the endemic Cyprinoidei fishes from the Balkan’s Dinaric karst

A remarkable diversification of the freshwater ichthyofauna in the Peri-Mediterranean is an outstanding legacy of the complex paleogeographical and evolutionary history of southern Europe. The Dinaric karst on the Balkan Peninsula harbours endemic cyprinoid genera including Phoxinellus and Delminichthys (fam. Leuciscidae), an ancient monotypic genus Aulopyge (fam. Cyprinidae) and endemic species of the Dinaric Telestes , Squalius and Phoxinus genera (fam. Leuciscidae). In this study, evolutionary body shape changes of these endemic European cyprinoid were explored using a geometric morphometrics approach in a phylogenetic framework. By projecting phylogeny obtained from cyt b mtDNA sequences into a morphospace, a strong phylogenetic signal was found in fish body shape, but not in size. Principal component analysis on both uncorrected and size-corrected (allometry free) shape variables revealed that closely related species tend to be clustered in the same area of morphometric space implying that evolutionary allometry did not significantly influence morphological evolution. Therefore, body shape might be used as a reliable taxonomic trait and indicator of phylogenetic relationships. The observed phylogenetic signal in body shape suggests that phylogenetic constraint affects the pattern of shape variation. The phylogenetic comparative method in exploring the evolutionary trend in the body form of Dinaric cyprinoids has not yet been assessed, and our preliminary findings suggested that the body shape diversification proceeded predominantly in the head region and body depth. The diversification of the freshwater ichthyofauna supported by both molecular phylogeny and morphological evolution is mostly a consequence of the complex paleogeographical and evolutionary history of the Peri-Mediterranean area.