Understanding the population structure of a species and the barriers that disrupt dispersal is important to accurately assess the global conservation status and manage the risk of local extinction. This is especially true for species of commercial importance (Begg et al., 1999) or conservation concern (Moritz, 1994), which are impacted disproportionally by anthropogenic or environmental pressures. Dispersal

The Yucatán Peninsula in Mexico contains some of the largest breeding groups of the globally distributed and critically endangered hawksbill turtle (Eretmochelys imbricata). An improved understanding of the breeding system of this species and how its genetic variation is structured among nesting areas is required before the threats to its survival can be properly evaluated. Here, we genotype 1195 hatchlings and 41 nesting females at 12 microsatellite loci to assess levels of multiple paternity, genetic variation and whether individual levels of homozygosity are associated with reproductive success. Of the 50 clutches analyzed, only 6% have multiple paternity. The distribution of pairwise relatedness among nesting localities (rookeries) was not random with elevated within‐rookery relatedness, and declining relatedness with geographic distance indicating some natal philopatry. Although there was no strong evidence that particular rookeries had lost allelic variation via drift, younger turtles had significantly lower levels of genetic variation than older turtles, suggesting some loss of genetic variation. At present there is no indication that levels of genetic variation are associated with measures of reproductive success such as clutch size, hatching success, and frequency of infertile eggs.

From the 32 worldwide post nesting Chelonia mydas sub populations 2 are found in the Mexican Coasts, one of them in Michoacan (Pacific Ocean) and the other in the Yucatán Peninsula (Atlantic Ocean). Lack of information about migration patterns, home ranges and anthropogenic interaction are factors that contribute to the int rinsic vulnerability of C. mydas populations anywhere around the world. The objective of this investigation was to identify migration routes and critical marine habitats for post nesting C. mydas individuals in the Yucatán Peninsula. Between June 2011 and January 2012 4 C. mydas post nesting individuals were tracked using satellite telemetry, 2 of them from continental beaches and the other 2 from insular ones. A geographic information system was used to integrate the collected information and used to identify migration routes for C. mydas as well as to estimate their home ranges. Three turtles moved and remained over the marine platform in the Banco de Campeche in Mexican territory, while one of the turtles migrated outside Mexican waters to Dry Tortuga (Florida, USA). The home ranges areas used by nesting females in continental beaches were significantly larger and further from the coast compared to those registered for females tracked from insular beaches. Based on the results we recommend management strategies planning for conservation of C. mydas in the Yucatán Peninsula.

Abstract.-Hatchling DNA provides valuable information on sea turtles. Samples can be obtained from dead hatchlings or embryo, or, when live animal samples are needed, from blood, flipper or carapace. We compared 120 DNA extractions from flipper and carapace tissue of dead and live hatchlings. There were significant differences in DNA yields from the different tissues, but no significant differences in DNA purity. Some flipper samples yielded low amounts of DNA, while the carapace tissue consistently produced high yields of good quality DNA. This suggests that carapace represents the best option for tissue sampling of hatchling sea turtles in genetic research.