Nuclear markers reveal a complex introgression pattern among marine turtle species on the Brazilian coast

A surprisingly high frequency of interspecific sea turtle hybrids have been previously recorded in a nesting site along a short stretch of the Brazilian coast. Mitochondrial DNA data indicated that as much as 43% of the females identified as E. imbricata are hybrids in this area (Bahia State of Brazil). It is a remarkable find, since most of the nesting sites surveyed worldwide, including some in northern Brazil, presents no hybrids, and rare Caribbean sites present no more than 2% of hybrids. Thus, a detailed understanding of the hybridization process is needed to evaluate natural or anthropogenic causes of this regional phenomenon in Brazil, which could be an important factor affecting the conservation of this population. We analyzed a set of 12 nuclear markers to investigate the pattern of hybridization involving three species of sea turtles: hawksbill (Eretmochelys imbricata), loggerhead (Caretta caretta), and olive ridley (Lepidochelys olivacea). Our data indicate that most of the ...