Three Modes of Evolution by Natural Selection and Drift: A New or an Extended Evolutionary Synthesis?

Abstract

According to sources both in print and at a recent meeting, evolutionary theory is currently undergoing change which some would characterize as a New Synthesis, and others as an Extended Synthesis. This article argues that the important changes involve recognizing that there are three means by which evolutionary change can be initiated (genetically, ecologically, and developmentally) and three corresponding modes of evolutionary drift. It compares the three and goes on to discuss the scale of innovation and extended or inclusive and Lamarckian inheritance. It concludes from these that “new trends in evolutionary biology” are in part a new, and in part an extended evolutionary synthesis.