Increased sample size provides novel insights into 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 ampli ed. 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.

Using ISSR markers to detect genetic variation for marine turtles populations in Egypt loggerhead (Caretta caretta) and green turtles (Chelonia mydas)

“…The total numbers of individuals (alive and stranded) were taken into consideration for the identification of populations' distribution to determine the significance of each selected study area for nesting foraging or both. As per Kaska et al, 4 Casale et al, 5 and Hochscheid et al, 6 the Egyptian Mediterranean coast might not be one of the important nesting areas in the Mediterranean, but it is known to be one of the most important areas as feeding ground and migratory corridors 7 in the Mediterranean basin. The studied areas of the Egyptian Mediterranean coast showed habitat fragmentation in the most of north coast areas due to massive touristic development and unplanned urbanization over the past 40 years.…”

Conservation Genetics of the Loggerhead Sea Turtle, Caretta caretta, from the Central Mediterranean: An Insight into the Species’ Reproductive Behaviour in Maltese Waters

“…Genetic data from the eight analysed nests indicated that the most common mtDNA CR haplotype is CC-A2.1, which is commonly proposed as the ancestral lineage for the Mediterranean Sea and was possibly introduced from the Atlantic Ocean by colonizing females in the last post-glacial period [ 20 , 21 , 41 , 55 ]. Currently, CC-A2.1 is the most commonly encountered haplotype, present in more than 60% of the free-living Mediterranean loggerhead sea turtles [ 21 , 56 , 57 , 58 , 59 , 60 ]. This haplotype dominates most Mediterranean nests and has been detected in all nesting areas studied [ 22 , 41 , 59 , 61 , 62 ].…”

“…Currently, CC-A2.1 is the most commonly encountered haplotype, present in more than 60% of the free-living Mediterranean loggerhead sea turtles [ 21 , 56 , 57 , 58 , 59 , 60 ]. This haplotype dominates most Mediterranean nests and has been detected in all nesting areas studied [ 22 , 41 , 59 , 61 , 62 ]. Haplotype CC-A3.1 is the second most commonly encountered haplotype in the Mediterranean Sea and accounts for around 20% of the free-living individuals studied [ 21 , 56 , 57 , 58 ].…”

“…CC-A3.1 was found to occur in high frequencies in two nesting sites, Dalyan and Dalaman in Turkey, where, in the latter, it was more common than CC-A2.1 [ 41 ]. The other haplotypes found in the Mediterranean occur at much lower frequencies in both free-living turtles and in analysed nests [ 41 , 59 , 60 ].…”

New colonisers drive the increase of the emerging loggerhead turtle nesting in Western Mediterranean

“…The D-Loop sequences were aligned, cut and blasted with published haplotype sequences found in the database maintained by the Archie Carr Center for Sea Turtle Research ( https://accstr.ufl.edu/ ) using BIOEDIT 89 . We identified the regular nesting region in which each haplotype was found following the haplotype frequencies found in previous studies 43 , 90 to determine the potential origin of the nesting females that laid each nest.…”