TRANSLATING BETWEEN MICROEVOLUTIONARY PROCESS AND MACROEVOLUTIONARY PATTERNS - THE CORRELATION STRUCTURE OF INTERSPECIFIC DATA

As species evolve along a phylogenetic tree, we expect closely related species to retain some phenotypic similarities due to their shared ev olutionary histories. The amount of expected similarity depends both o n the hierarchical phylogenetic structure, and on the specific magnitu de and types of evolutionary changes that accumulate during each gener ation. In this study, we show how models of microevolutionary change c an be translated into the resulting macroevolutionary patterns. We ill ustrate how the structure of phenotypic covariances expected in inters pecific measurements can be derived, and how this structure depends on the microevolutionary forces guiding phenotypic change at each genera tion. We then explore the covariance structure expected from several s imple microevolutionary models of phenotypic evolution, including vari ous combinations of random genetic drift, directional selection, stabi lizing selection, and environmental change, as well as models of punct uated or burst-like evolution. We find that stabilizing selection lead s to patterns of exponential decrease of between species covariance wi th phylogenetic distance. This is different from the usual linear patt erns of decrease assumed in most comparative and systematic methods. N evertheless, linear patterns of decrease can result from many processe s in addition to random genetic drift, such as directional and fluctua ting selection as well as modes of punctuated change. Our framework ca n be used to develop methods for (1) phylogenetic reconstruction; (2) inference of the evolutionary process from comparative data; and (3) c onducting or evaluating statistical analyses of comparative data while taking phylogenetic history into account.