Are the native giant tortoises from the Seychelles really extinct? A genetic perspective based on mtDNA and microsatellite data.
Abstract
The extinction of the giant tortoises of the Seychelles Archipelago has long been
suspected but is not beyond doubt. A recent morphological study of the giant tortoises
of the western Indian Ocean concluded that specimens of two native Seychelles species
survive in captivity today alongside giant tortoises of Aldabra, which are numerous
in zoos as well as in the wild. This claim has been controversial because some of
the morphological characters used to identify these species, several measures of carapace
morphology, are reputed to be quite sensitive to captive conditions. Nonetheless,
the potential survival of giant tortoise species previously thought extinct presents
an exciting scenario for conservation. We used mitochondrial DNA sequences and nuclear
microsatellites to examine the validity of the rediscovered species of Seychelles
giant tortoises. Our results indicate that the morphotypes suspected to represent
Seychelles species do not show levels of variation and genetic structuring consistent
with long periods of reproductive isolation. We found no variation in the mitochondrial
control region among 55 individuals examined and no genetic structuring in eight microsatellite
loci, pointing to the survival of just a single lineage of Indian Ocean tortoises.
Type
Journal articleSubject
AnimalsDNA Primers
DNA, Mitochondrial
Genetic Variation
Geography
Microsatellite Repeats
Population Dynamics
Seychelles
Species Specificity
Turtles
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