VERTEBRATE DIVERSITY
Vertebrate faunas of the Mediterranean Basin share the characteristic of multiple biogeographic origins with vascular plants. Dramatic climatic oscillations during the Pleistocene led to periodic turnovers of Eurasian and African faunal elements and a resulting isolation of populations.
The present fauna of land mammal species for the Mediterranean Basin number about 224 species of which 25 are endemic. Because of the biogeographic barriers of the Mediterranean Sea and the Saharan Desert, mammal faunas of Mediterranean Europe, the Middle East and North Africa are somewhat distinct. For North Africa, the mammal fauna of the Mediterranean Basin shows its strongest affinities with tropical Africa. A decline in species richness occurred at the end of the Pleistocene and into the Holocene with a combination of sharp climate shifts and human pressures through hunting.
Bird diversity of the Mediterranean Basin includes about 497 regularly occurring species. In contrast to mammals, the affinities of bird faunas are more strongly linked to the Asiatic steppes than to tropical Africa. The evolution of these elements of bird faunas can be linked to Eurasian (153 species) and Eremian semiarid habitats (85 species), where Plio-Pleistocene conditions led to ongoing isolation and speciation. Forest birds of boreal origin are widespread and dominant throughout both middle Europe and the Mediterranean Basin. Shrubland bird species characteristic of the region represents only about 12% of the total. There are 32 endemic bird species in the Mediterranean Basin.
Reptiles and amphibians of the Mediterranean Basin include 228 and 77 species, respectively, and show distinct holarctic affinities. Much of the endemism within these groups appears to represent archaic lineages that differentiated during the middle Tertiary. Reptile diversity is highest in the eastern Mediterranean Basin and drops steadily moving westward. Species diversity on Mediterranean islands is relatively low. Important reptile groups include lizards of the Lacertidae with 63 species (23% of the world total), snakes of the Viviperidae with 19 species (8% of the world total), and tortoises of the Testunididae with four species. Overall, 34% of Mediterranean Basin reptiles are endemic to this region. For amphibian diversity, the pattern is reversed compared with reptiles as the highest levels of diversity are found in the Euro-Mediterranean areas compared with the North African and Middle Eastern portions of the region. Notable groups of amphibians include the Discoglossidae with 10 species (71% of the world total) and the Salamandridae with 19 species (36% of the world total). Endemism for amphibians in the Mediterranean Basin is 31%.
Fish diversity is relatively high in the Mediterranean Basin compared to the other MTEs, with 216
species. This group includes 63 endemic species, six endemic genera, and one endemic family.