Research

Tempo and mode in evolution

Nothing in biology makes sense except in the light of evolution.
 Th. Dobzhansky
A long-standing debate in evolutionary biology concerns whether species diverge gradually through time or by punctuational episodes at the time of speciation. The latter describes a punctuation pattern where episodes of stasis alternate with bursts of evolutionary change. Despite years of work on arguments between gradual evolution and punctuational evolution, the problem remains that these analyses were mostly restricted to morphological data without supporting genome-wide molecular data and there is little or no consensus as to the contribution of punctuational changes to evolutionary divergence. Some studies have provided evidences of the punctuational contribution of speciation to evolutionary divergence at the molecular level. Recent macroevolutionary studies involving thousands of bird species have suggested that rates of phenotypic evolution have been heterogeneous and punctuational across clades and time periods, but it remains unresolved whether there are connections with genome level rates of molecular evolution. Thus, we aim to reconstruct the tempo and mode of genome evolution that drove episodes of explosive diversification of birds, a theme that George Gaylord Simpson originally identified as belonging to the realm of paleontology. By integrating the rich phenotypic data available for birds, we will further p develop phylogenetic models to explicitly estimate covariances between rates of molecular and phenotypic evolution.