Prom fly development to evolution

摘要

A major conundrum in evolutionary biology, about as old as the discipline itself, has been the question of how major changes in body form can come about. Darwin himself insisted on a strict gradualism in all evolutionary change. Even the radical reorganization of body plans was assumed by Darwin to proceed through many small, graded steps. This view, still widely held, carries with it a number of problems, not the least of which is the glaring absence from the fossil record of the necessary continuously varying intermediate forms in evolutionary lineages.