MEPS 424:273-283 (2011)  -  DOI:

Population structure of the loggerhead turtle Caretta caretta, a large marine carnivore that exhibits alternative foraging behaviors

Kunihiro K. Watanabe1,9, Hideo Hatase1,*, Masato Kinoshita2, Kazuyoshi Omuta3, Takeharu Bando4, Naoki Kamezaki5, Katsufumi Sato6, Yoshimasa Matsuzawa5, Kiyoshi Goto7, Yoshito Nakashima8, Hiroshi Takeshita8, Jun Aoyama1, Katsumi Tsukamoto1

1Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8564, Japan
2Graduate School of Agriculture, Kyoto University, Sakyo, Kyoto 606-8502, Japan
3Yakushima Sea Turtle Research Group, 489-8 Nagata, Yakushima, Kagoshima 891-4201, Japan
4Institute of Cetacean Research, 4-5 Toyomi, Chuo, Tokyo 104-0055, Japan
5Sea Turtle Association of Japan, 5-17-18-302 Nagao-motomachi, Hirakata, Osaka 573-0163, Japan
6International Coastal Research Center, Atmosphere and Ocean Research Institute, The University of Tokyo, Otsuchi, Iwate 028-1102, Japan
7Minabe Sea Turtle Research Group, 278 Higashiyoshida, Minabe, Wakayama 645-0001, Japan
8Miyazaki Wildlife Animal Research Group, 9779-8 Shimanouchi, Miyazaki 880-0121, Japan
9Present address: National Institute for Land and Infrastructure Management, 1 Asahi, Tsukuba, Ibaraki 305-0804, Japan
*Corresponding author. Email:

ABSTRACT: Knowledge of detailed population genetic structure is crucial to conserve and manage endangered species effectively. Size-related variation in feeding-habitat use (neritic vs. oceanic) by adult loggerhead turtles Caretta caretta has been reported within several populations, and sympatric population subdivision was suspected. In the present study, genetic differences between the 2 feeding-habitat groups within 2 Japanese nesting sites were assessed, using 5 microsatellite loci and mitochondrial (mt) DNA sequences. There were no genotypic or haplotype differences between the feeding-habitat groups, which were defined by egg-yolk stable isotope ratios and body size, at both nesting sites, suggesting that both neritic and oceanic individuals belong to the same genetic population. Differences in feeding-habitat use are unlikely to be a limiting factor for gene flow between feeding-habitat groups and were thought to be the result of phenotypic plasticity rather than population subdivision. Gene flow among 5 nesting sites was assessed by pooling these feeding-habitat groups at each nesting site. Significant genetic structure by female natal homing was observed at the mtDNA level. However, no significant structure was found at the microsatellite DNA level, suggesting male-mediated gene flow caused by migration through courtship areas. Although nesting beaches are connected by male-mediated gene flow, which might have evolved as a mechanism to avoid genetic fragmentation by natal homing, extirpated beaches would not be easily recolonized from other nesting populations due to female philopatry. Therefore, conservation of individual nesting beaches is still needed to maintain the overall genetic diversity of Japanese loggerheads.

KEY WORDS: Alternative life histories · Microsatellite DNA · Mitochondrial DNA · Phenotypic plasticity · Reptile · Caretta caretta

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Cite this article as: Watanabe KK, Hatase H, Kinoshita M, Omuta K and others (2011) Population structure of the loggerhead turtle Caretta caretta, a large marine carnivore that exhibits alternative foraging behaviors. Mar Ecol Prog Ser 424:273-283.

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