Increased Sample Size Proved More Insights for the Population Structure of Mediterranean Loggerhead Sea Turtles

Abstract

The loggerhead sea turtle (Caretta caretta), has the broadest distribution among sea turtle species in the Mediterranean and requires regional and international collaborations in addition to local efforts to better inform conservation actions. Molecular techniques are powerful tools to assess population dynamics at large scales, especially by determining the connectivity among different nesting and foraging sites, and genetic diversity. In this study, a large sample was collected synchronously in the nesting areas located in the north, south and east of the Mediterranean. Recently described nesting sites from Albania and other nesting sites represented by lower sample size were also included in order to fully assess the genetic composition of the region’s rookeries. Samples from 710 individuals were collected and the longer (815 bp) mtDNA D-loop fragment of these samples was amplified. We recorded 15 haplotypes, three of which were novel. In addition, our results show that some haplotypes, considered of Atlantic origin, have a wider dispersal in the Mediterranean than previously thought, albeit with low levels of representation. Our results, which also contribute to determining the likely origin of haplotypes that were previously known only from foraging sites, highlight the utility of broad-scale sampling, with increased sample number and longer mtDNA sequence to determine genetic diversity and connectivity. This study also demonstrates that it is important to continue to monitor the contribution of Atlantic origin haplotypes to the Mediterranean population, and the resident Mediterranean population, which is expected to expand its geographical range for reproduction with the effect of climate change and climate change in the long term. This work is important for, among other things, mixed stock analyses (MSA) that seek to localize the origin of stranded or accidentally caught sea turtles or those purposefully obtained from foraging sites to better understand the migratory distribution for conservation purposes.