Stasis in Progress: The Empirical Basis of Macroevolution

Abstract

The theory and practice of macroevolutionary study have moved from the seat of the pants, to the back of an envelope, to the printed page. In the course of this journey, important ideas have surfaced and have too often been confused through a combination of inadequate original presentation of concepts and widely varying reinterpretations. For example, macromutations have been represented as hopeful monsters, that is, as coordinated, novel structures of highly improbable origin within the normal spectrum of mutations (75, 80, 148, 175). But a macromutation can also be described as a highly probable mutation that has important consequences for structure and evolution (65). This confusion stems from the common habit, not limited to evolutionary biology, of creating an intellectual dichotomy while failing to define both sides of the issue precisely. It is as if two countries decided to fight a war without any conception of who were the citizens on each side. This problem is illustrated well by Goldschmidt's (76) argument for a large-scale mutation in the origin of Batesian mimicry. Subsequent work (45, 46) has demonstrated that a large mutation is indeed the cornerstone of mimicry by the swallowtail Papilio dardanus. But there is nothing mysterious or monstrous about this variant; the major mutation, moreover, is supported by several minor changes that com­ plete the construction of the mimetic phenotype. One wonders about the utility