Filogeografia genômica e hibridização em tartarugas marinhas

Abstract

Sea turtles have a complex life cycle, with life stages closely related to humans. This interaction exposes them to threats caused by anthropic impact, which lead to a global population decline for all species. In addition, an extremely high incidence of hybridization among sea turtles along the Brazilian coast is an atypical situation to be investigated. Thus, understanding the evolutionary history and population dynamics and investigating the impact of the hybridization process among sea turtles is essential for the species conservation. In this work we initially analyze the global phylogeographic patterns of hawksbill turtle (Eretmochelys imbricata) through the compilation of mitochondrial haplotype data available in the literature. Important global demographic patterns were being missed due to the use of non-representative data or non-standard haplotype nomenclature. Our results allowed us to identify the connectivity among populations, to recognize knowledge gaps that should be prioritized in future research, and to reinforce the need for international efforts focused on species conservation. Next, we performed a study of phylogeography, demography and hybridization of sea turtles along the Brazilian coast through a multilocus approach. New genetic markers were selected using the ddRADseq technique and used to detect inter and intraspecific variation for the five sea turtle species that occur along the Brazilian coast and for hybrid individuals. Our results suggest that there is a male-mediated gene flow between the rookeries along the Brazilian coast for hawksbill and loggerhead (Caretta caretta) turtles. We also estimate that the phenomenon of high frequency hybridization occurring in Bahia is probably even more recent than previously suggested, as only F1 hybrid adults were found. Finally, we investigate the Abrolhos Archipelago nesting population of loggerhead turtles, through genetic data and reproductive monitoring. Our results showed that Abrolhos is also a nesting area for hybrids, and female hybrids appear to present a lower reproductive success than “pure” females. In conclusion, this thesis allowed us to advance the knowledge about the phylogeographic and phylogenetic processes of sea turtles and demonstrated how the genetic analysis associated with ecological data can contribute to the understanding of important phenomena for the species conservation.