Investigating Evolutionary Radiations

摘要

Life today is hugely diverse and yet the origins of that biodiversity are only dimly understood.Charles Darwin saw the temporal and geographic linkages between modem and ancient organisms,and he argued that life arose from a single ancestor,and major groups arose by "descent with modification".We must thank Darwin for the tree metaphor in evolution.Modem studies are beginning to reveal the relationship between diversity (species richness) and disparity (variation in form),and the importance of both factors in generating modem biodiversity.Classic models of adaptive radiation suggest that major clades expand initially rapidly,and that a great deal of change in disparity happens before the major diversity jump.The Cretaceous Terrestrial Revolution,from 120-80 Ma ago,marked the dramatic rise of angiosperms in terrestrial ecosystems and their role triggering massive diversifications among arthropods and vertebrates.New data sets and new statistical tools show patterns of diversification as well as the piecemeal manner in which many key innovations,or novelties,were constructed and their seemingly ad hoc genomic regulation.