# Genomic Differentiation and Diversity in Persian Gulf Hawksbill Turtles (Eretmochelys imbricata) Revealed by the First Whole-Genome Sequencing Study

## TL;DR

This study uses whole-genome sequencing to reveal genetic differences among hawksbill turtles in the Persian Gulf, showing the need for site-specific conservation strategies.

## Contribution

The first whole-genome sequencing study of Persian Gulf hawksbill turtles reveals fine-scale genetic differentiation and demographic history.

## Key findings

- Genetic differences were found between turtles from nearby nesting areas in the Persian Gulf.
- Natal homing and environmental factors drive genetic differentiation among populations.
- Low nucleotide diversity and past bottlenecks were identified in Persian Gulf hawksbill populations.

## Abstract

Hawksbill sea turtles (Eretmochelys imbricata) are critically endangered. The nesting populations in the Persian Gulf are not well studied or described. We sequenced whole genomes from individuals sampled across four islands in the northern Persian Gulf and found genetic differences between turtles from spatially proximate nesting areas, despite having long life spans and overlapping foraging locations. Genetic sampling already shows differences across nesting areas. These differences could be explained by natal homing and environmental heterogeneity in the nesting areas, implying that the conservation of individual nesting beaches is essential and that the loss of one could result in the loss of an entire genetic lineage. Our results thus provide a genomic basis for more informed site-specific conservation in this region.

This is the first WGS study of the hawksbill sea turtle (Eretmochelys imbricata) from the Persian Gulf. Sequencing of 17 individuals from four nesting islands in the southern part of Iran’s coastline revealed population-level genetic differentiation with consistently low rates of nucleic diversity and differentiated demographic footprints in sampling populations in the Persian Gulf. In a population structure analysis, four populations were discovered; Shidvar had long-term isolation and Nakhiloo demonstrated admixture and higher heterogeneity. ROH and LD profiles are consistent with past bottlenecks, rather than recent inbreeding, and reflect each island’s demographic history. The observed fine-scale genomic divergence (e.g., even between sites in close proximity, such as Ommolgorm and Nakhiloo) suggests that natal homing and local environmental selection are meaningful drivers of genetic differentiation, and that specific conservation strategies should be implemented at each site.