Chromosomal evolution in large pelagic oceanic apex predators, the barracudas (Sphyraenidae, Percomorpha).

Abstract

Sphyraena (barracudas) represents the only genus of the Sphyraenidae family and includes 27 species distributed into the tropical and subtropical oceanic regions. These pelagic predators can reach large sizes and, thus, attracting significant interest from commercial and sport fishing. Evolutionary data for this fish group, as well its chromosomal patterns, are very incipient. In the present study, the species Sphyraena guachancho, S. barracuda, and S. picudilla were analyzed under conventional (Giemsa staining, C-banding, and Ag-NOR) and molecular (CMA3 banding, and in situ hybridization with 18S rDNA, 5S rDNA, and telomeric probes) cytogenetic methods. The karyotypic patterns contrast with the current phylogenetic relationships proposed for this group, showing by themselves to be distinct among closely related species, and similar among less related ones. This indicates homoplasic characteristics, with similar karyotype patterns originating at least twice, independently. Although still cytogenetically poor investigated, our data were enough to put in evidence a variety of ancient conserved traits and evolutionary novelties for the Sphyraena genus. In this sense, it is fundamental that a larger number of Sphyraenidae species, as well as of other phylogenetically related families, be also investigated. This will solidify the knowledge of their karyotypic patterns, and the evolutionary path followed by the species of this particular fish family.