Interpreting Morphological and Molecular Data on Indian Ocean Giant Tortoises

Abstract

Since 1877 it has been assumed that human exploitation led to the\r extinction of all Indian Ocean giant tortoises except for the Aldabran\r Dipsochelys dussumieri. A taxonomic review in 1998 proposed that two\r further species survived in captivity. Some recent molecular studies\r question the validity of these taxa. All available evidence is\r re-examined in a discussion of the identity of the Seychelles giant\r tortoises.\r Morphological data identifies three living morphotypes (D. dussumieri,\r D. arnoldi and D. hololissa), data on wild and captive growth\r distinguishes these from the results of abnormal growth. Molecular data\r is less clear cut with conflicts between different studies. RAPDs\r identify the morphotypes although microsatellites identify very little\r population structuring. Different mtDNA genes conflict, with ND4\r sequences relating to the different morphotypes but cytochrome b failing\r to do so.