Green turtle population structure in the Pacific: new insights from single nucleotide polymorphisms and microsatellites

Abstract

A set of nuclear single nucleotide polymorphisms (SNPs) and microsatellite markers was used to detect genetic stock structure among 5 Pacific green turtle Chelonia mydas nesting populations. We sampled populations in the Galapagos Islands, Ecuador (n = 57), Colola, Mexico (n = 75), French Frigate Shoals, Hawaii (n = 141), Yap, Micronesia (n = 73), and Wan-an, Taiwan (n = 57), to represent eastern, central, and western Pacific regions. A combination of 29 single independent SNPs and linked SNPs combined as haplotypes were used for a total of 20 independent markers. In addition, 8 polymorphic microsatellite markers were applied to the same sample set. Both sets of nuclear markers confirmed significant differentiation between all sampled populations in the 3 Pacific regions (p ≤ 0.001). The use of these SNPs and microsatellites resulted in sufficient power to detect small population differences not seen in previous studies using smaller numbers of nuclear markers. Our results suggest that male-mediated gene flow between regional nesting stocks is more limited than previously believed, allowing the potential to delineate stocks more clearly. Finally, we discuss the value of SNP markers as an alternative or complement to other nuclear markers such as microsatellites for the examination of stock structure.

Genetic fingerprinting reveals natal origins of male leatherback turtles encountered in the Atlantic Ocean and Mediterranean Sea

“…One powerful genetic tool, assignment testing, may be used to determine the source nesting populations of individual animals sampled in foraging or developmental habitats . Female sea turtles have previously been shown to have high levels of site fidelity to a beach or region (Bowen and Karl 2007;Wallace et al 2010;Stewart and Dutton 2014;Bannister et al 2016), and distinct genetic signatures of populations (or management units, MUs) reaffirm these findings (e.g., Dutton et al 2013;Jensen et al 2013;Roden et al 2013;Shamblin et al 2014). Foraging site fidelity is also observed in many sea turtle species, and most foraging areas are composed of mixed stocks (i.e., they are a mixture of individuals from various nesting populations) (James et al 2005;Velez-Zuazo et al 2008Schofield et al 2010.…”

Mitochondrial DNA short tandem repeats unveil hidden population structuring and migration routes of an endangered marine turtle

“…Among those, genetics has been the preferred method to evaluate population structure. The levels of connectivity among populations can be inferred through the degree of genetic differentiation retained as a result of isolation (Matsuzawa et al, ; Roden et al, ), and can also reflect the historical processes that shaped the actual distributions (Clusa et al, ). Contemporary movements of individuals can also be tracked using tag–recapture techniques (Rees et al, ), satellite telemetry (Stokes et al, ), or stable isotopes (Hobson, ), thus linking reproductive areas with developmental and foraging areas.…”

Connectivity, population structure, and conservation of Ecuadorian green sea turtles

“…For instance, the circumtropical green turtle Chelonia mydas has the widest and most continuous distribution of all hard-shelled sea turtle species (Vieyra 2006). Previous work on C. mydas shows that re gional genetic structure has been shaped by both intrinsic (behavior and ecology) and extrinsic (geographic, climate, and oceanography) events (Seminoff et al 2008, Roden et al 2013, Dutton et al 2014a, Hamabata et al 2014. For example, current levels of genetic diversity are potentially the result of glacial and inter-glacial paleo-oceanic periods that created opportunities for the establishment of new migratory routes (Formia et al 2006, Hamabata et al 2014.…”