Population genomic analysis reveals high inbreeding in a Hawksbill turtle population nesting in Singapore

Seven species of marine turtles remain in a world currently threatened by anthropogenic activities and climate change, standing at the precipice of extinction. Urgent conservation endeavours are imperative to safeguard their survival and preserve the biodiversity of marine ecosystems. Yet, genetic studies on these turtles have leaned on restricted genetic markers, such as the mitochondrial control region. The markers could provide incomplete or biased estimations of genetic diversity and population structure, thereby limiting precise conservation strategies. Here, we have generated a de novo genome assembly and high-quality whole-genome population datasets from hawksbill turtles nesting and foraging in Singapore. This initiative aims to contribute to unbiased, fine-resolution genetic data on the species, conducting a comprehensive population genomic study. Our analysis results demonstrated a remarkable enhancement in genetic markers. While we identified five different haplotypes defined by five variants within 69 mitochondrial control region sequences, the analysis of 35 whole genome sequences uncovered approximately 12 million single nucleotide polymorphisms (SNPs). Within the Singapore hawksbill turtle population, our whole-genome analysis revealed a pronounced degree of inbreeding, with most samples sharing at least a first cousin relationship. Furthermore, within a multiple-paternity nest, we identified related parents. Additionally, our inference of demographic history underscored the impact of past climate change on the decreasing hawksbill turtle population. We believe this pioneering study will substantially enhance the field of conservation genetic study of marine turtles.