Data from: Large-scale connectivity, cryptic population structure, and relatedness in Eastern Pacific olive ridley sea turtles (Lepidochelys olivacea)

Endangered species are grouped into genetically discrete populations to
direct conservation efforts. Mitochondrial Control Region (mtCR)
haplotypes are used to elucidate deep divergences between populations, as
compared to nuclear microsatellites that can detect recent structuring.
When prior populations are unknown, it is useful to subject microsatellite
data to clustering and/or ordination population inference. Olive ridley
sea turtles (Lepidochelys olivacea) are the most abundant sea turtle, yet
few studies have characterized olive ridley population structure.
Recently, clustering results of olive ridleys in the Eastern Tropical
Pacific Ocean suggested weak structuring (FST=0.02) between Mexico and
Central America. We analyzed mtCR haplotypes, new microsatellite genotypes
from Costa Rica, and pre-existing microsatellite genotypes from olive
ridleys across the Eastern Tropical Pacific, to further explore population
structuring in this region. We subjected inferred populations to multiple
analyses to explore the mechanisms behind their structuring. We found 10
mtCR haplotypes from 60 turtles nesting at three sites in Costa Rica, but
did not detect divergence between Costa Rican sites, or between Central
America and Mexico. In Costa Rica, clustering suggested one population
with no structuring, but ordination suggested four cryptic clusters with
moderate structuring (FST=0.08, p<0.001). Across the Eastern
Tropical Pacific, ordination suggested nine cryptic clusters with moderate
structuring (FST=0.103, p<0.001) that largely corresponded to
Mexican and Central American populations. All ordination clusters
displayed significant internal relatedness relative to global relatedness
(p<0.001) and contained numerous sibling pairs. This suggests that
broadly dispersed family lineages have proliferated in Eastern Tropical
Pacific olive ridleys and corroborates previous work showing basin-wide
connectivity and shallow population structure in this region. The
existence of broadly dispersed kin in Eastern Tropical Pacific olive
ridleys has implications for management of olive ridleys in this region,
and adds to our understanding of sea turtle ecology and life-history,
particularly in light of the natal-homing paradigm.