Dynamics of taxonomic diversity

摘要: A general model of taxonomic diversity, incorporating diversity-dependent rates origination and extinction, is constructed to examine the dynamic responses diversity perturbation. The predicts that trajectories diversification increase decrease are substantially different. during disequilibrium conditions displayed in phase diagrams permit a simple graphical analysis stability. positive displacement from equilibrium results rapid decline may involve an initial overshoot condition. negative equal magnitude gradual diversity. expressed as nonlinear difference equation incorporate intrinsically delay time due characteristic noninstantaneous response extinction. initially assumes parabolic curve expressing total taxon rate function second model, assuming sigmoidal derived considerations allopatric speciation, enhances asymmetry response. delayed recovery Triassic fauna shown be return undersaturated condition, whereas more “catastrophic” Late Permian oversaturated It proposed, although not assumed, perturbation include degree selectivity related dispersal abilities organisms, thereby enhancing observed asymmetry.