Fire and its role in coexistence and speciation in Gondwanan shrublands

The floras mediterranean south-western Australian shrublands (kwongan) and south-western Cape jynbos have evolved under conditions low soil nutrients and recurrent The vegetatiOn oj both regions, here termed Gondwanan shrublands, is broadly convergent in structure and junctioning. In particular these shrublands have high species diversity at all levels. Fire has played an important role in the evolution oj traits and life histories on both continents. Populations respond difjerentially to varying components oj the fire regime and post-jire population extinction is not uncommon. Since each fire is a event, high alpha richness could be maintained by the creation oj fire-induced transient niches resulting in difjerential establishment. Under this jorm oj 'lottery' recruitment, competitive are weakened and many species same guild can coexist. It is postulated that recurrent jire is a driving jorce in the massive specil.1tion the Gondwanan shrubland Small demes would be isolated in peculiar habitats ajter jire-induced population. jragmentation. Strong disruptive selection would result in the rapid evolution oj isolated populations into distinct and specialized species. Some tests jar these hypotheses are presented and the implications jar conservation are Iy discussed.