When physical oceanography meets population genetics: The case study of the genetic/evolutionary discontinuity in the endangered goliath grouper (Epinephelus itajara; Perciformes: Epinephelidae) with comments on the conservation of the species

• A low genetic diversity was confirmed in Epinephelus itajara.
• The species is divided into two genetic/evolutionary lineages.
• A possible ESU of E. itajara occurs at the Babitonga bay (Southern Brazil).
• Physical oceanography explains the isolation at the Babitonga bay (Southern Brazil).
• Also a panmictic population occurs in the rest of the Atlantic coast of South America.

Epinephelus itajara is one of the marine fish species most threatened for extinction and it is considered to be “critically endangered” by the IUCN. The present study evaluated the genetic diversity of the species and the genetic/evolutionary relationships of its populations along the Atlantic coast of South America. The results indicate relatively reduced genetic variation, re-emphasizing the low adaptive potential of the species. One of the populations presented relatively high degrees of genetic diversity and it is evolutionary isolated from the all other populations. The evidences indicate the existence of two Evolutionarily Significant Units comprising E. itajara in the Atlantic coast of South America and the conservation prospects for the species must take these evidences into account.