Geographic distribution of an extinct equid (Equus hydruntinus : Mammalia, Equidae) revealed by morphological and genetical analyses of fossils

摘要

Equus hydruntinus inhabited Europe and the Middle East for more than 300 000 years. For a long time, palaeontological data failed to place E. hydruntinus into the equid phylogenetic tree, confronted with the fact that it shares primitive Equus characters with both zebras and asses, and derived characters with asses and hemiones. However, the study of a recently discovered skull points to a relationship with hemiones. Extraction of DNA from ancient samples from Crimea (E. hydruntinus) and Iran (E. cf. hydruntinus) yielded 134-288 bp of the mtDNA control region and 143 bp of the cytochrome b gene. This DNA analysis supports the proximity of E. hydruntinus and Equus hemionus suggested by skull and limb bone analyses, and rejects proximity to either Equus burchelli or the asses suggested by tooth morphology. Dental morphology may thus be of poor taxonomical value if used alone for establishing equid phylogenetic relationships. Furthermore, the small genetic distance between E. cf. hydruntinus of Iran and the classical E. hydruntinus of Crimea suggests that both samples belong to the same species. Accordingly, the geographic range of E. hydruntinus - until now believed to be restricted to Europe, Israel, and Turkey - can be extended towards East as far as Iran.