The Mediterranean Basin is particularly noted for its spectacular array of endemic plants, with 52 percent of the 22,500 species found nowhere else in the world (2). The level of endemism is especially high on the islands of the Mediterranean, where species have evolved to survive in very specific habitats (2) (6). The Maltese rock-centaury (Cheirolophus crassifolius) grows only on the windy cliffs of Malta (3) whilst the pink-flowered Silene hicesiae is only known to occur on the slopes of two volcanic islets (7).
Due to the long history of human occupation in the Mediterranean Basin, many of the forests have been replaced by floristically rich scrubland (2). This ubiquitous Mediterranean scrub is sometimes classified in to different types, depending on factors such as the plant composition and soil type, although the boundaries between these are blurred, producing a mosaic of plant communities (3) (8). Perhaps the most iconic inhabitant of the scrubland is the olive tree (Olea europaea), a small, evergreen tree best known for its edible fruit (3) (9). A range of familiar aromatic shrubs such as lavender (Lavandula), thyme (Thymus) and rosemary (Rosmarinus) also grow there, along with medically important plants like felty germander (Teucrium polium) (3) (10). As well as providing an array of habitats, this complex mixture of plants puts on a spectacular floral display every spring (3).
The forested areas of the Mediterranean Basin are much more diverse than those found in other areas of Europe (2) (3). Of the 290 tree species native to the Mediterranean Basin, an incredible 201 are endemic (2). The cedar of Lebanon (Cedrus libani) in particular is renowned for its timber, having been utilised for thousands of years and now holding pride of place on the Lebanese flag (11). The only palm species native to Europe, the Cretan date palm (Phoenix theophrasti), is also found in the Mediterranean Basin, existing in a few scattered populations in Crete and Turkey (12) (13).
The Mediterranean Sea is host to a range of unique plants, including up to 200 endemic macroscopic species (4). One of the most important marine vegetation types, however, is the meadows of seagrass, such as Posidonia oceanica, which supports over 80 percent of the fish yield in the Mediterranean (4).
Despite the Mediterranean Basin having fewer mammal and bird species than other biodiversity ‘hotspots’, it is still home to 220 mammal species, an impressive 11 percent of which are endemic to the region (2).
One of the most charismatic species, the Critically Endangered Mediterranean monk seal (Monachus monachus), uses the secluded sea caves of the region to breed in. Europe’s only species of primate, the Barbary macaque (Macaca sylvanus), and the world’s most threatened species of cat, the Iberian lynx (Lynx pardinus), also live in the Mediterranean region, along with 23 of the world’s 85 cetacean species (2) (14).
As well as being home to around 500 species of bird, 25 of which are endemic, the Mediterranean Basin is an important migration route, with some two billion birds travelling to, or through, the region every year (2) (3).
Of the year-round residents in the Mediterranean Basin, the Spanish imperial eagle (Aquila adalberti) is perhaps one of the most stunning. The spectacular array of endemic species also includes the Raso lark (Alauda razae) and the Balearic shearwater (Puffinus mauretanicus) (2). The region also harbours populations of globally threatened bird species, including the Dalmatian pelican (Pelecanus crispus), the marbled duck (Marmaronetta angustirostris) and the slender-billed curlew (Numenius tenuirostris) (2).
Reptiles and amphibians
An amazing diversity of reptiles exists in the Mediterranean Basin, with 48 percent of the 355 reptile species occurring nowhere else in the world (15). The lizards of the genus Gallotia occur only on the Canary Islands and include the Gran Canaria giant lizard (Gallotia stehlini), the Tenerife speckled lizard (Gallotia intermedia) and the Hierro giant lizard (Gallotia simonyi) (15).
Many of the amphibian species are also unique to the region, with 64 percent of the 106 species being endemic (15). Fascinating examples of the amphibian diversity include the Mallorcan midwife toad (Alytes muletensis) and the cave salamander (Proteus anguinus) (14) (15).
Fish and invertebrates
Encompassing both freshwater and marine habitats, the Mediterranean Basin unsurprisingly has a wide range of aquatic inhabitants. The Mediterranean Sea is home to some 519 species of bony fish, sharks and rays, of which 74 species are endemic (14). The freshwater habitats are also very diverse, with 60 endemic species, including the Ghizáni (Ladigesocypris ghigii), which has recently been saved from extinction by careful management of its habitat (2) (14).
With so many plants in the Mediterranean region there is an associated high diversity of invertebrates (3). About 75 percent of the estimated 150,000 European invertebrate species occur in the Mediterranean Basin (16). Scorpions, cicadas, dragonflies and a array of colourful butterflies are but a few of the invertebrate groups that live there (6).