Biology subjects

Honarvar, S.

Publications and source records attributed to Honarvar, S..

3 recordsLinked to original sources

bioRxiv2026

Genomic indicators of risk and resilience in global leatherback turtle populations

Understanding the drivers of genomic health and their consequences for population viability is often overlooked but potentially important to effective conservation amidst the biodiversity crisis of the Anthropocene. Leatherback turtle (Dermochelys coriacea) populations have declined globally due to anthropogenic factors, with some populations losing over 90% of their abundance over the past 30-50 years. While conservation efforts have been successful in stabilizing some populations, others continue to decline, and the reasons for these differential trajectories remain unclear. To assess how recent demographic factors, such as population size and decline, influence population genomic health, we combined population monitoring information with medium depth whole-genome and reduced representation resequencing data from globally representative populations. We found that small-stable populations have lower genomic diversity and higher inbreeding than large declining populations, reflecting prolonged small population sizes and limited gene flow. Yet, small-stable populations also show evidence of deleterious allele purging, suggesting genetic resilience. This, combined with lack of detectable genomic erosion over the study period, provides hope for potential recovery of healthy leatherback populations provided that anthropogenic threats are effectively mitigated. However, potential time lags and possible recent increases in inbreeding among close relatives in recently declined populations warrant continued monitoring and assessment. Genomic and abundance-based metrics were less aligned following rapid population declines, emphasizing the different timescales of the evolutionary and demographic processes they reflect, respectively, and the strength in their complementary, integrative use for extinction risk assessments. This also supports that it is not too late to turn the tide for recently declined leatherback populations and that continued investment in conservation efforts and threat reductions are warranted. Collectively, our results highlight how recent and historical demography shapes current genomic health and recovery potential in leatherback turtles, aids understanding of current risks and informs future conservation and management strategies.

ecology↗

bioRxiv2019

Predicting the impacts of sea level rise in sea turtle nesting habitat on Bioko Island, Equatorial Guinea

Sea level is expected to rise 44 to 74 cm by the year 2100, which may have critical, previously un-investigated implications for sea turtle nesting habitat on Bioko Island, Equatorial Guinea. This study investigates how nesting habitat will likely be lost and altered with various increases in sea level, using global sea level rise (SLR) predictions from the Intergovernmental Panel on Climate Change. Beach profiling datasets from Biokos five southern nesting beaches were used in GIS to create models to estimate habitat loss with predicted increases in sea level by years 2046-2065 and 2081-2100. The models indicate that an average of 62% of Biokos current nesting habitat could be lost by 2046-2065 and 87% by the years 2081-2100. Beach D is predicted to be the least vulnerable to increases in sea level. Erosion and tall vegetation berms have been documented on Beaches A and B, causing green turtles to nest uncharacteristically in front of the vegetation line. Development plans are currently underway for Beach D. With Beach D being the least susceptible to future increases in sea level, development and anthropogenic encroachment here would be especially detrimental to nesting turtle populations. Identified habitat sensitivities to SLR will be used to inform the government of Equatorial Guinea to consider the vulnerability of their resident turtle populations and projected climate change implications when planning for future development. To our knowledge this is the first study to predict the impacts of SLR on sea turtle nesting habitat in Africa.

ecology↗

bioRxiv2019

Newly Discovered migratory corridor and foraging ground for Atlantic green turtles, Chelonia mydas, nesting on Bioko Island, Equatorial Guinea

This study is the first to use satellite telemetry to track post-nesting movements of endangered green turtles (Chelonia mydas) in the Gulf of Guinea. Satellite transmitters were attached in 2018 to six Atlantic green turtles nesting on Bioko Island, Equatorial Guinea, to track their post-nesting movements and locate their foraging grounds. Track lengths of 20-198 days were analyzed, for a total of 536 movement days for the six turtles. Migratory pathways and foraging grounds were identified by applying a switching state space model to locational data, which provides daily position estimates to identify shifts between migrating and foraging behavior. Turtles exhibited a combination of coastal and oceanic migrations pathways that ranged from 957 km to 1,131 km. Of the six turtles, five completed their migration and maintained residency at the same foraging ground near the coastal waters of Accra, Ghana until transmission was lost. These five resident turtles inhabit heavily fished and polluted waters and are vulnerable to a variety of anthropogenic threats. The identification of these foraging grounds highlights the importance of these coastal waters for the protection of the endangered Atlantic green turtle.

zoology↗