Population genetics of two species of threatened sharks from the Southwestern Atlantic: preliminary results

TROVANT, B.; BASSO, N. G.; SANCHEZ CABRERA, M.A.; ALVAREZ GALLEGO, F.; DE WYSIECKI, A.; IRIGOYEN, A.

Congreso; 66° Congreso Brasilero de Genética y II Congreso Latinoamericano de Genética para la Conservación; 2021

Sharks are marine animals of great ecological importance and are currently among the most threatened species in marine ecosystems. The broadnose sevegill shark (Notorynchus cepedianus) and the school shark (Galeorhinus galeus) are commonly found in temperate coastal areas around the world and are currently listed on the IUCN Red List as “Vulnerable” and “Critically Endangered”, respectively, however there are still gaps in understanding of their populations connectivity. The aim of this work was to investigate the genetic structure of these two species of sharks in the Southwest Atlantic and their connectivity at a global scale, in order to provide vital information to develop management and conservation strategies. To determine whether these species have a panmictic distribution or are comprised of different populations, the COI mitochondrial gene was amplified and sequenced in a total of seven sevengill sharks and eight school sharks. Sequences of these species available in the Genbank database were used to complement the study. Two genetically distinct populations of sevengill sharks were identified globally, rejecting the hypothesis of global panmixia. In addition, four genetically distinct populations were identified among school sharks globally, also rejecting the hypothesis of global panmixia. The potential barriers to gene flow associated with these shark species are the water temperature at the tropics and the great distances between ocean basins. Despite the fact that the genetic distances found between the populations of each species are not sufficient to consider them as distinct species, the unique genetic diversity found within each population suggests the need to consider each one as independent when developing and applying management and conservation measures