Inferring boundaries among fish species of the New World silversides (Atherinopsidae; genus Odontesthes): new evidences of incipient speciation between marine and brackish populations of O. argentinensis

GONZÁLEZ-CASTRO, MARIANO; ROSSO, JUAN JOSE; DELPIANI, SERGIO MATIAS; MABRAGAÑA, EZEQUIEL; DÍAZ DE ASTARLOA, JUAN MARTÍN

GENETICA

SPRINGER

Lugar: Berlin; Año: 2019

0016-6707

Species of New World silversides (Actinopterygii; Atherinopsidae; genusOdontesthes) possess economic relevance, biological interest and ecological importance. In the present paper we: A) Investigate the molecular diversity in marine species of Odontesthes from the South West Atlantic Ocean (SWAO), and analyse their interspecific relationships and divergence by means of DNA Barcoding, including its freshwater congeners, as well. B) Explore the suitability of DNA Barcoding to analyse the diversity and distribution of haplotypes in O. argentinensis, the only well documented marine species from the SWAO that exhibit putative estuarine and marine populations.Molecular analysis revealed 100% of agreement between morphological identification and molecular identity. Odontesthes argentinensis, O. platensis, O. smitti, O. nigricans and O. incisa were assigned to five different barcode index numbers (BINs). Maximum likelihood analysis showed that all marine species of Odontesthes clustered separately in a unique monophyletic phylogroup, comprising five well defined haplogroups, with genetic divergence between groups ranging from 2.75 to 7.11%. The genetic analysis including freshwater congeners showed that O. incisa clustered alone occupying a basal position. The Fst pairwise comparisons within O. argentinensis support the existence of three population groups: one conformed by Mar Chiquita Lagoon (MCh) specimens, and the others by Mar del Plata/Mar Chiquita coast and San Blas Bay coastal specimens, respectively. The AMOVA showed significant overall differentiation (Fst = 0.238; p = 0.00001) for the entire data set. The previous/present evidence is discussed, and strongly suggests that incipient speciation is occurring in O. argentinensis argentinean populations, and specimens from MCh would be considered at present as the leading candidate of a marine to freshwater incipient speciation event.