Genetic structure of Octopus mimus Gould, 1852 along three biogeographic marine provinces

The population genetic structure of a species is frequently shaped by biogeographic barriers that prevent the movement of individuals from one genetic population to another. Although Octopus mimus Gould, 1852 was reported to inhabit the shallow marine waters of the Peruvian province, recent studies suggest its synonymy with O. hubbsorum Berry, 1953 from the Panamanian and the Cortez provinces where it is the main octopus species caught in the artisanal fishery. The aim of the present study was to assess the genetic variability of O. mimus and to determine the presence of population structure across three sampled regions of the eastern Pacific Ocean using the mitochondrial marker cytochrome c oxidase subunit I. The hypothesis that the biogeographic boundary between the Panamanian and Peruvian provinces acts as a genetic break was further tested and recognized by the conformation of two phylogenetic clades and two haplogroups. Results indicate that these lineages are demographically independent populations of O. mimus and do not represent different species as evidenced by the Generalized Mixed Yule Coalescent method. The oceanographic processes have apparently allowed enough genetic flow along the Pacific coast yielding low but significant levels of genetic structure (FST = 0.16, p < 0.05) as seen in some fish populations.