ECOLOGICAL STUDIES ON REPTILIAN COMMUNITIES IN SOME OASES OF THE EGYPTIAN WESTERN DESERT

Abstract

The aim of this work is to identify and describe reptilian fauna of the Western Desert oases and to develop a historical biogeographic framework to explain the present distribution and phylogentic relations of members of these fauna. The study was carried out in the oases of Siwa, Bahariya, Farafra, Dakhla, Kharga and Faiyum where both habitats and Herpetofauna were surveyed. The specimens were examined for morphological, morphometric and meristic measurements. Electrophoretic protein fractionation was carried out for Cerastes Cerastes and Echis pyramidum venom and serum from different oases. Similarity between the structure of reptilian communities of different oases, as well as between the oases populations of Echis pyramidum and Cerastes cerastes were investigated. A number of distinct ecosystems within the oases depressions were identified and described. The herpetofaunal survey resulted in six species that were recorded for the first time from some oases. The results of the biogeographical analysis showed that the reptilian fauna of the Western Desert Oases consists of an assemblage of mesophilic, xerophilic and semi-desert species. Their distribution reflects the climatic and ecological history of the region. Throughout the Quaternary Period, extremely arid areas in the Sahara harbored xerophilic species even during wet climatic episodes. Similarly, mesic refuges supported mesophilic species even during extremely dry climatic episodes. The Nile Valley and the Western Desert oases constitute the mesic refuges for several reptilian species of mesophilic ecological affinity. Numerous hyperarid habitat patches, including those at the fringes of major oases are the ecological refuges of