Efficiency of DNA barcoding for phylogenetic analysis and species identification in flying fish (Exocoetidae)

Abstract

The article reports DNA barcoding (sequencing of the cox 1 mitochondrial gene fragment) of five South Atlantic flying fish species belonging to family Exocoetidae together with the results of the comparative analysis of cox 1 variability in the Exocoetidae and its closely related family Hemiramphidae. It has been demonstrated that DNA barcoding can be used as an extra tool for species identification and phylogenetic analysis in flying fish, since species identification accuracy using the cox 1 gene sequence proved to be 88%, or 78% when intraspecies variability level is taken into account. We have confirmed monophyletic origin of certain species, genera, and subfamilies of flying fish except for the genus Cheilopogon, which was represented on the phylogenetic tree by three paraphyletic clades. One of them shows close relationship to the genus Cypselurus, while another encompasses Hirundichthys genus species. The Exocoetidae is characterized by much lower overall genetic divergence level compared to the Hemiramphidae (average intraspecies differences: 10.2 ± 0.4% vs. 18.1 ± 0.8%; average intrageneric differences: 13.3 ± 1.1% vs. 21.3 ± 1.8%), which may indicate that the former group is relatively young in terms of evolution. No intraspecies differentiation was observed for Exocoetus obtusirostrus across a significant geographic distance (>3000 km). Phylogenetic reconstructions based on the variability of conservative (cox 1 mtDNA) and more variable regions of mitochondrial and nuclear genomes and on the adaptive morphological traits associated with gliding flight development were shown to coincide to a large extent.