Kemp’s ridley Lepidochelys kempii nesting abundance in Texas, USA: a novel approach using genetics to improve population census

Abstract

Accurate estimates of the annual numbers of nesting females are critical for assessing sea turtle populations. Nesting by Kemp's ridley Lepidochelys kempii turtles has significantly increased at Padre Island National Seashore and nearby beaches in Texas, USA. Four nests were observed in Texas during 1995 and a record of 209 in 2012. However, it is unclear how many clutches are laid by the same females. We used a genetic approach to infer the number of individual nesters from genotypes determined from dead embryos and hatchlings sampled from clutches. Mitochondrial DNA sequencing was combined with nuclear DNA analysis at 10 micro satellite loci to match genotypes for nesters and offspring of unknown parentage in over 50% of the unassigned nests. Our results indicate that traditional methods, based on observed tagged turtles, have underestimated the number of Kemp's ridleys nesting in Texas. We demonstrate how genetic approaches can be incorporated into population assessments when direct census of adult animals is not feasible. This approach also provides a basis to apply capture−mark−recapture techniques to assess the impact of events, such as the recent oil spill, on the population via sampling of nests to identify and track individual nesters over time.

Combining Harvest and Genetics to Estimate Reproduction in Wolves

“…We also found that sibship frequency‐based estimates of the effective number of breeders were consistent across sample years and had overlapping confidence intervals with estimates based on linkage disequilibrium, another commonly employed single‐sample N b estimator. The value of estimating counts of parents and family groups through sibship reconstruction has been demonstrated in other systems, such as monitoring abundance of social bee colonies by identifying sisters among foraging workers and estimating the number of female sea turtles (green [ Chelonia mydas ] and Kemp's ridley [ Lepidochelys kempii ] sea turtles) laying multiple clutches per season at the same nesting site (Toquenaga and Kokuvo ; Frey et al , ; Geib et al ). Fisheries and aquaculture systems have used similar methods to shed light on genetic variability between age stages, assess stocking strategies, and reconstruct putative parental genotypes among externally fertilized species (Liu and Ely , Li et al , Meraner et al , Hasanat et al ).…”

First report of an olive ridley (Lepidochelys olivacea) inside the Mediterranean Sea

“…Positive (a previously analysed loggerhead turtle (Caretta caretta) sample) and negative controls were also included. Sequences were aligned manually by the BioEdit programme, version 5.0.9 (Hall, 1999), and were compared with the haplotypes described for both species of the genus Lepidochelys, as found in the literature (Bowen et al, 1998;Shanker et al, 2004; López instead of Lopez-Castro & Rocha-Olivares, 2005; Reis et al, 2010;Jensen et al, 2013;Frey et al, 2014) and in the GenBank database (National Center for Biotechnology Information, USA: NCBI Home page http://www.ncbi.nlm.nih.gov) by a BLAST search. When sequences were not available in Genbank, they were extracted from the polymorphic tables found in the references that describe them.…”

Advances in the Application of Genetics in Marine Turtle Biology and Conservation

“…Nest sampling may also supplement traditional tagging approaches thus improving annual censuses of nesting populations where nesting females cannot be consistently observed. For example, Frey et al (2014) used parentage analysis and genetic fingerprinting for a limited number of known Kemp's ridley mothers along with hatchlings from unidentified nests to assign mothers for every nest. They TABLE 3 | Generalized summary of marine turtle genetic/genomic research to inform future project development.…”