Figure 1

Schematic representation of the turnover-pulse and the resource-use hypotheses. Iterative and differential evolution of clades related to variations in biomic specialization as predicted by the turnover-pulse and the resource-use hypotheses (modified from Vrba [25, 26]). During severe environmental changes, extinction rates of stenobiomic lineages reach their apex, giving rise to critical biotic events in which generalist species constitute most of the survivors. After each critical event the development of new specialist lineages with faster speciation rates generates specialists-dominated faunas as the environmental conditions are stabilized.