TY  - BOOK
AU  - Herath, D.R.
AU  - Ranmadugala, D.N.A.
AU  - Jayathilake, R.A.M.
AU  - Gunawardena, M.G.K.
TI  - Hybridization between a Hawksbil  turtle (Eretmochelys imbricata) and an Olive Ridley turtle (Lepidochelys olivacea) revealed  by  mitochondrial  DNA  analysis
PY  - 2008///,
CY  - Sri Lanka
PB  - Sri Lanka Association for Fisheries and Aquatic Resources
N2  - Molecular genetic techniques have been useful in studying natural hybridization in marine turtles. As morphological features by themselves are inadequate in the determination of hybridization, mitochondrial DNA analysis has been commonly used for the study of hybrid turtles. Hybridizations have been detected and reported using these methods among almost all the species in the family Cheloniidae.
Five turtles from a clutch of turtles hatched in a Kosgoda turtle hatchery in 1996 were believed to be hybrids due to the presence of intermediate features. Considering these morphological features it had been believed at that time that they were hybrids between a Hawksbill turtle (Eretmochelys imbricata) and a Green turtle (Chelonia mydas). As four of these hybrid turtles had been killed during the tsunami in 2004, only one hybrid turtle was available for this study.
The morphological features of a Hawksbill turtle observed in this particular turtle, were the possession of 2 pairs of prefrontal scutes and the presence of 4 infra marginal scutes without pores. Though the central scutes were imbricated, the marginal scutes were not very clearly imbricated. The presence of a curved beak with a distinct overbite, a characteristic feature of Hawksbill turtles, was not observed in this specimen.
Mitochondrial DNA analysis was carried out to confirm hybridization. The four species of turtles commonly found in Sri Lanka, Green turtle (Chelonia mydas), Loggerhead turtle (Caretta caretta), Hawksbill .turtle (Eretmochelys imbricata) and Olive Ridley turtle (Lepidochelys olivacea), were used to determine the origin of the hybrid turtle. The results showed that the four species of turtles cluster together in their own separate clades and that the hybrid turtle clusters with the Olive Ridley turtle specimens.
As mitochondrial DNA has a maternal origin and as some morphological features characteristic of a Hawksbill turtle were observed, it could be inferred that the hybrid is a progeny of a female Olive Ridley turtle and a male Hawksbill Turtle. This proves that this hybrid turtle is not a result of a cross between a Hawksbill turtle and a Green turtle, a conclusion that had been reached using only its morphological features
ER  -