Fire and Plant Diversification in Mediterranean-Climate Regions

摘要: Despite decades of broad interest in global patterns biodiversity, little attention has been given to understanding the remarkable levels plant diversity present world's five Mediterranean-type climate (MTC) regions, all which are considered be biodiversity hotspots. Comprising Mediterranean Basin, California, central Chile, Cape Region South Africa, and southwestern Australia, these regions share unusual climatic regime mild wet winters warm dry summers. their small extent, covering only about 2.2% world land area, home approximately one-sixth vascular flora. The onset MTCs middle Miocene brought summer drought, a novel condition, but also recurrent fire. Fire significant agent selection assembling modern floras four MTC with Chile an exception following uplift Andes Miocene. Selection for persistence fire-prone environment as key causal factor species diversification under-appreciated or ignored. Mechanisms fire-driven speciation diverse may include both directional (novel traits) stabilizing (retained appropriate morphological life-history traits. Both museum nursery hypotheses have important relevance explaining extant richness floras, fire strong stimulant manner distinct from other temperate floras. Spatial temporal niche separation across topographic, edaphic gradients occurred regions. seen nurseries not spectacular rates Neogene diversification, while older landscapes Australia show components Paleogene younger diversity. Low extinction suggesting long association more than high richness.