Spatio-temporal patterns of mitochondrial DNA variation in hawksbill turtles (Eretmochelys imbricata) in Southeast Asia

Hawksbill turtles (Eretmochelys imbricata) are exploited for their beautiful shell known as tortoiseshell or bekko, making them extremely vulnerable in the illegal global trade of tortoiseshell products. In this study, we developed an effective, standardized method using a commercially available kit to extract DNA and obtain informative mitochondrial DNA (mtDNA) control region sequences (~800 bp) from hawksbill turtle products in order to trace the sample back to a likely stock origin. We also sequenced additional skin samples from nesting beaches of Milman Island, Australia and Arnavon Island, Solomon Islands to add to the baseline data for hawksbill turtles in the Indo-Pacific. Our results indicate that nine of the 13 tortoiseshell products obtained from Papua New Guinea and Solomon Islands were from turtles with haplotypes found primarily at the Solomon Islands rookery and did not match those from nesting populations in Australia or SE Asia, with the exception of one haplotype also found in 3% of turtles at Milman Island. We also found that 23% of the market samples have haplotypes only documented in foraging populations, which illustrates the urgent need for more extensive sampling of rookeries to fill gaps in the reference baseline database. Nevertheless, our study results demonstrate an effective methodology for obtaining DNA of sufficient quantity and quality from hawksbill turtle products.

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Genetic studies of the Hawksbill turtle Eretmochelys imbricata: evidence for multiple stocks in Australian waters

Pacific Conservation Biology ◽

10.1071/pc940123 ◽

1994 ◽

Vol 1 (2) ◽

pp. 123 ◽

Cited By ~ 35

Author(s):

D. Broderick ◽

C. Moritz ◽

J. D. Miller ◽

M. Guinea ◽

R. I. T. Prince ◽

...

Keyword(s):

Mitochondrial Dna ◽

Western Coast ◽

Geographic Scale ◽

Long Distance ◽

Eretmochelys Imbricata ◽

Dna Variation ◽

Use Patterns ◽

Breeding Populations ◽

Significant Difference ◽

Dna Types

The hawksbill turtle, Eretmochelys imbricata, is endangered and currently declining in many parts of its global distribution. Efforts to manage the species are hampered by the lack of knowledge of the appropriate geographic units of management and the relationship among breeding populations and feeding assemblages. The Australian populations are among the few remaining large assemblages in the world, but may be under threat from harvesting in neighbouring countries. We use patterns of mitochondrial DNA variation to determine the geographic scale of breeding populations and to compare the genetic composition of turtles in feeding populations to those nesting at nearby major rookeries. Four of the major Australian rookeries were sampled, two on the western coast and two in northeastern Australia, as were turtles at two foraging sites. Significant differences in the frequency of two divergent mitochondrial DNA types separated the turtles nesting at major rookeries sampled on the northeastern versus western coasts of Australia, demonstrating that these populations are not connected by significant amounts of gene flow and should be considered as separate entities for management. There was no significant difference between the turtles nesting at two western rookeries 100 km apart, nor between those using the two northeastern rookeries separated by 750 km. This indicates that the size of the interbreeding unit for the hawksbill turtle is likely to be a region consisting of a group of islands rather than an individual island. Feeding populations were screened with a gene amplification test that discriminates between the two major DNA types. In each case, there was a significant difference in allele frequency between feeding populations and the nearest major rookery. This, together with previous reports of long distance migrations from tag returns, suggests that individual foraging areas support hawksbill turtles from distant breeding populations.

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