Dispersal of green turtles from Africa’s largest rookery assessed through genetic markers

Abstract

Marine turtles are highly migratory species that establish multiple connections among distant areas, through oceanic migration corridors. To improve the knowledge on the connectivity of Atlantic green turtles, we analysed the genetic composition and contribution to juvenile aggregations of one of the world's largest rookeries at Poilão Island, Guinea-Bissau. We amplified 856bp mitochondrial DNA (mtDNA) control region sequences of this population (n=171) containing the ~490bp haplotypes used in previous studies. Haplotype CM-A8 was dominant (99.4%) but it divided in two variants when the whole 856 bp was considered: CM-A8.1 (98.8%) and CM-A8.3 (0.6%). We further identified the haplotype CM-A42.1 (0.6%), found previously only in juvenile foraging grounds at Argentina, Brazil and Equatorial Guinea. The Poilão breeding population was genetically different from all others in the Atlantic (FST range 0.016-0.961, P< 0.001). An extensive 'Many-to-many' mixed-stock analysis (MSA) including 14 nesting populations (1,815 samples) and 17 foraging grounds (1,686 samples) supported a strong contribution of Poilão to West Africa (51%) but also to Southwest Atlantic (36%). These findings, in particular the strong connectivity within West Africa, where illegal harvesting is still common, should motivate conservation partnerships, so that population protection can be effectively extended through all life-stages. Our study expands the knowledge on migration patterns and connectivity of green turtles in the Atlantic, evidences the importance of larger sample sizes and emphasises the need to include more finely resolved markers in MSAs and more genetic sampling from West African foraging grounds to further resolve the connectivity puzzle for this species.

How many came home? Evaluating ex situ conservation of green turtles in the Cayman Islands

“…All but one had been previously described in populations in the Caribbean Sea, South America, South Atlantic (Ascension Island; Formia, Godley, Dontaine, & Bruford, ) and Africa (Shamblin, Bagley et al, ; Shamblin, Dutton et al, ). The haplotypes found in our samples belonged to different lineages as defined in the literature (Naro‐Maciel et al, ): most haplotypes belonged to lineage A (84%), which is typically found in the Caribbean, while the rest belonged to lineage B (Figure ) typically found in South America, South Atlantic and Africa (Patrício et al, ; Shamblin, Bagley et al, ; Shamblin, Dutton et al, ). CM‐A5.1 is the only haplotype of lineage B found shared by both the captive and the wild populations; however, this haplotype is not exclusive of the South Atlantic region and can be found in other wild populations of the Caribbean region (Naro‐Maciel et al, ).…”

“…South Caribbean populations are AVE = Aves Island (Venezuela) and SUR = Matapica (Suriname) (Bolker, Okuyama, Bjorndal, & Bolten, ). South Atlantic populations are ASC = Ascension Island, BIO = Bioko Island (Equatorial Guinea), SAO = Sao Tome (Formia et al, ), TI = Trinidad Island (Trinidad y Tobago), RA = Rocas Atoll and FN = Fernando de Noronha (Brazil), and POI = Poilao (Guinea Bissau) (Patrício et al, ; Shamblin, Dutton et al, )…”

“…Haplotype CM‐A8.1 is the most abundant in Ascension Island (Naro‐Maciel et al, ), one of the source populations of the founder stock. Haplotype CM‐A42.1 is exclusive to Poilao (Patrício et al, ) where it coexists at low frequency with CM‐A8.1. As the populations of Poilao and Ascension are genetically similar (Patrício et al, ), finding the CM‐A42.1 haplotype in the farm would imply that this haplotype is also found in Ascension Island but has yet to be discovered there.…”

“…Both D‐loop and STR sequences were also used to confirm maternal assignments resulting from microsatellite analysis. Using D‐loop sequences we performed analysis of wild and captive populations compared to other wild populations of the Caribbean (Shamblin, Bagley et al, ), African (Patrício et al, ; Shamblin, Dutton et al, ) and Mediterranean (Bradshaw et al, ) regions. Incorporating D‐loop sequences from these populations, we tested for genetic structuring ( F ST ) and genetic diversity.…”

Genetic composition and origin of juvenile green turtles foraging at Culebra, Puerto Rico, as revealed by mtDNA

“…Atlantic green turtle (Chelonia mydas) foraging grounds (n = 18, dark triangles and black star for study site) and nesting populations (n =14, gray circles) included in this study, with respect to major ocean currents: GfC: Gulf Current, NEC: North Equatorial Current, SEC: South Equatorial Current, BrC: Brazil Current, GC: Guinea Current, BgC: Benguela Current. Nesting populations: EcFL and SFL: Florida, USA (Shamblin et al, 2014); CUB: southwest Cuba (Ruiz-Urquiola et al, 2010); MEX: Quintana Roo, Mexico (Encalada et al, 1996); CR: Tortuguero, Costa Rica (Bjorndal et al, 2005b;Encalada et al, 1996); SUR: Matapica and Galibi, Suriname (Encalada et al, 1996;Shamblin et al, 2012); AV: Aves Island (Lahanas et al, 1998(Lahanas et al, , 1994Shamblin et al, 2012), Venezuela; BUC: Buck Island (Shamblin et al, 2012); RC/FN: Rocas Atoll and Fernando Noronha (Bjorndal et al, 2006;Encalada et al, 1996), Brazil; ASC: Ascension Island (Encalada et al, 1996;Formia et al, 2007); TRI: Trindade Island, Brazil (Bjorndal et al, 2006); GB: Poilão, Guinea-Bissau (Patrício et al, 2017); BIO: Bioko Island, Equatorial Guinea ; STP: Sao Tome and Principe . Foraging grounds: NC: North Carolina (Bass et al, 2006), HI: Hutchinson Island, Florida (Bass & Witzell, 2000), DT+EP: Dry Tortugas + Everglades Park, Florida (Naro-Maciel et al, 2016), SJ: St. Joseph Bay, Florida (Foley et al, 2007), TEX: Texas (Anderson et al, 2013), USA; BHM: Bahamas (Lahanas et al, 1998), CUL: Culebra, Puerto Rico (this study), BRB: Barbados (Luke et al, 2004), ALF: Almofala, Brazil (Naro-Maciel et al, 2007), RC: Rocas Atoll, Brazil ), FN: Fernando Noronha, Brazil (Naro-Maciel et al, 2012, BA: Bahia, Brazil , ES: Espirito Santo, Brazil , UB: Ubatuba, Brazil (Naro-Maciel et al, 2007), AI: Arvoredo Island, Brazil (Proietti et al, 2012), CB: Cassino Beach, Brazil (Proietti et al, 2012), BuA, Buenos Aires, Argentina (Prosdocimi et al, 2012), CV: Cape...…”