Fig. 1: Study design.

A Location of the Cayman Islands in the Caribbean Sea. The white star shows the location of the Cayman Turtle Farm (CTF). B Samples used for the study. In dark blue, number of hatchlings analysed from Grand Cayman (2013-2015) and in light blue, number of hatchlings analysed from Little Cayman (2014-2015). In orange, wild adult females sampled from nesting beaches in Grand Cayman, and in grey, CTF female breeders, including original founders of the captive population, a multiannual (1986-2002) cohort of first-generation breeders (F1(mixed)) and the cohort of 1995 first generation breeders (F1(1995)). Wild and captive female genotypes are from a previous study²⁷. C Flowchart of analyses performed in our study. Each hatchling was collected from a different nest and genotyped at 13 microsatellite loci. Genotypes of hatchlings were combined with those of wild female to perform parentage assignment and with CTF female breeder genotypes to assess relatedness to the CTF. Geographic coordinates, nesting dates and reproductive data for each nest assigned to a wild female were extracted from the Department of Environment (DOE, Cayman Islands Government) database to assess nest-site fidelity, nesting dynamics and fitness. Lines indicate what sources of data (genotypes, geographic coordinates, nesting dates and reproductive data) and outputs of the different analyses (parentage assignment and CTF relatedness) interact to provide the different results (coloured boxes), as detailed in the Methods section. Photograph by Anna Barbanti.