Speciation environments and centres of species diversity in southern Africa: 2. Case studies

Abstract

Distributions of species in the grass genera Cymbopogon, Digitaria, Ehrharta and Stipagrostis are mapped to show that speciation within the phytochorion, where a genus has undergone major adaptive radiation (‘phytochorial sympatry’), may be differentiated from speciation in a phytochorion outside this characteristic one (‘phytochorial allopatry’). Testing of this hypothesis seems a fruitful field for systematists and will enhance our understanding of the flora.