Biodiversity Hotspots in the Mediterranean Basin: Setting Global Conservation Priorities

Due to the current species extinction crisis, there is an urgent need to identify the most threatened areas of exceptionally high biodiversity and rates of endemism (i.e., "hotspots"; Mittermeier et al. 1998; Myers 1988; Reid 1998). Conservation strategies represent a crucial issue in the mediterranean biome because this area, which represents only 2% of the world's surface, houses 20% of the world's total floristic richness (Medail & Quezel 1997). Myers initially (1988, 1990) defined 14 hotspots in the tropical biome and four in mediterranean bioclimates (southwestern Australia, Cape Region of South Africa, California, and part of Chile). Like the four other mediterranean areas, the Mediterranean Basin is one of the world's major centers for plant diversity, where 10% of the world's higher plants can be found in an area representing only 1.6% of the Earth's surface (Medail & Quezel 1997). The prominent role played by these areas as reservoirs for plant biodiversity has been emphasized by Myers (1990). He hesitated, however, to group the whole Mediterranean Basin into one single hotspot because it covers such a large surface area, and insufficient data were available for certain regions. In this context, Medail and Quezel (1997) performed a global survey of plant richness and endemism to more precisely define hotspots in the Mediterranean Basin; they identified 10 hotspots. Three main approaches, however, have been taken in recent studies performed by international conservation organizations to define priority conservation areas in the Mediterranean Basin.