DNA barcoding of marine rocky reef fishes from northern Peru suggests a parapatric speciation in the Tropical Eastern Pacific

Northern Peru marks the end of an extensive coastal marine region: The Panama province, which is characterized by predominantly tropical and equatorial features and is home to the only rocky reefs known in Peruvian territory. This unique ecosystem could explain the presence of a diverse range of fish species. However, due to the difficulty of sampling and accessing reef areas, our knowledge of this biodiversity is incomplete. To address this issue, we used DNA barcoding for the study of the fish biodiversity and revealed patterns that may have influenced their evolution throughout the Tropical Eastern Pacific (TEP). A fragment of Cytochrome oxidase subunit I (COI) of 177 samples of rocky reef fishes was sequenced. Intra and interspecific K2P distances were calculated and three species delimitation methods (GMYC, PTP, and bPTP) were used to obtain MOTUs. Both analyses support the conformation of additional MOTUs in samples of <i>Mugil cephalus</i>, <i>Ophichthus zophochir</i>, <i>Malacoctenus tetranemus</i>, <i>Ariopsis seemanni</i> and <i>Halichoeres dispilus</i>, species with a divergence above 2%. By comparing these sequences with public data, our analysis revealed the existence of COI lineages and suggested potential ecological parapatric speciation in the TEP. More studies using other markers and different approaches are required to confirm the existence of species complexes that could be related to the presence of cryptic species.