Population genetics of the hawksbill sea turtle (Eretmochelys imbricata; Linnaeus, 1766) in the Persian Gulf: structure and historical demography

This study focuses on the population genetics and historical demography of the hawksbill sea turtle (Eretmochelys imbricata) in the Persian Gulf. We selected eight distinct locations along its nesting habitat, covering a 750-km stretch of coastline, and collected 127 maternal DNA samples in one season using non-invasive methods. The samples were analyzed using 15 microsatellite loci, revealing distinctive genetic structures on islands and beaches, even when between locations as little as 50 km apart. The highest genetic diversity was observed for Qeshm Island, while lower genetic diversity was observed for Shidvar and Kharkoo islands and for Nayband Bay, possibly due to limited nesting habitat availability and disturbances related to tourism. The fixation index (F_ST) and gene flow parameter (N_m) values also identified population differentiation, with moderate to high differentiation observed among most populations. We also used population structure analysis, migration analysis, and population history reconstruction to identify multiple genetic clusters, and obtained support for a scenario of simultaneous dispersal in the Persian Gulf when the region became fully inundated with water approximately 10,000 years ago. Although the first introduction of hawksbill sea turtles into the Persian Gulf occurred from the Oman Sea through the Strait of Hormuz, they were distributed in all current habitats within a short time. The study emphasizes the importance of each coastal and island region in the Persian Gulf as a distinct genetic reservoir for hawksbill turtles. It also underscores the significance of conservation efforts to protect the genetic diversity and resilience of these endangered marine turtles, especially on nearby islands.