In-depth genomic analysis of hybridization between sea turtles

Hybridization between sea turtle species occurs with particularly high frequency in some populations in Brazil. We have been using state-of-the-art genomic techniques to evaluate the extent of hybridization occurrence, the possible deleterious effects in the hybrid progeny and the consequences for sea turtle conservation.

Project details

Duration:	since 2018
Third-party funded:	yes (partially)
Involved Department(s):	Dept Evolutionary Genetics
Leibniz-IZW Project Leader(s):	Camila Mazzoni (Dept Evolutionary Genetics)
Leibniz-IZW Project Team:	Camila Mazzoni, Larissa Arantes, Maximilian Driller (all: BeGenDiv/Dept Evolutionary Genetics)
Consortium Partner(s):	Fabrício Rodrigues dos Santos Abrolhos National Marine Park
Current Funding Organisation:	-
Research Foci:	Understanding traits and evolutionary adaptations Improving population viability Developing theories, methods, and tools

Sea turtles comprise an ancient group of marine vertebrates suffering from severe threats due to anthropogenic actions. One evolutionary phenomenon has been recently detected in high proportions on northeastern coast of Brazil - hybridization between different sea turtle species. This involves mainly three Carettini species with separation times of up to 29 million years: hawksbill (Eretmochelys imbricata), loggerhead (Caretta caretta) and olive ridley turtle (Lepidochelys olivacea). The existence of fertile female hybrids has been confirmed in different studies. However, our investigation has shown that the second generation of hawksbill-loggerhead hybrids present signs of outbreeding depression. It is potentially a major concern for depleted populations – as in the critically endangered hawksbills - and should therefore be understood in deepness in order to guide suitable managements actions. The lower reproductive success of hybrids relative to parental species may occur due to disruption of local adaptation, the breakup of coadapted gene complexes, and/or the expression of hybrid incompatibilities.

We have been using state-of-the-art techniques (reduced-representation and whole genome sequencing) to generate very high-quality data to (1) predict outcomes of hybridization for sea turtle conservation, and (2) enrich the knowledge upon sea turtle genomic composition, aiming to identify candidate areas of the genome that show incompatibility in backcrossed individuals. Furthermore, we have been developing bioinformatics methods to study genetic variability of sea turtles.

Selected Publications

Arantes LS, Ferreira LCL, Driller M, Filho FPMR, Mazzoni CJ, Santos FR (2020): Genomic evidence of recent hybridization between sea turtles at Abrolhos Archipelago and its association to low reproductive output. SCI REP 10, 12847. doi:10.1038/s41598-020-69613-8

Arantes LS, Vilaça ST, Mazzoni CJ, Santos FR (2020): New genetic insights about hybridization and population structure of hawksbill and loggerhead turtles from Brazil. J HERED 111, 444–456. doi:10.1093/jhered/esaa024

Arantes LS, Vargas SM, Santos FR (2020): Global phylogeography of the critically endangered hawksbill turtle (Eretmochelys imbricata). Genet Mol Biol. 43(2):e20190264. doi:10.1590/1678-4685-GMB-2019-0264