The speciation revolution

Abstract

I predict the years 1990±2010 will be seen as a revolution in the study of speciation. One person's punctuated equilibrium is another's gradual change, and the current revolution is in any case paltry compared with Darwin's own. Even so, many previously accepted beliefs about speciation are now doubted, and features of a classic scienti®c revolution are evident. To see just how much has changed, consider what experts were saying until recently. Coyne (1994), for example, listed four major achievements due to Ernst Mayr since the 1940s. These were: (1) an appreciation of the reality of species (as compared with, say, the unreality of subspecies or genera); (2) the reproductive isolation de®nition of species (the `biological species concept'); (3) the generality of allopatric speciation; and (4) founder-effect speciation. Coyne (1994) argued that Mayr's fourth achievement, the founder effect, was probably incorrect, but regarded the other three as completely in tune with the current view of speciation. What is extraordinary about this list is that all these `achievements' are now, only 7 years later, rejected by major groups of evolutionary biologists. Softening on points (1) and (4) are found today even in papers coauthored by Coyne himself (Kliman et al., 2000; Turelli et al., 2001). The opinions under attack date from the 1930s to the 1950s, and are identi®ed strongly with Theodosius Dobzhansky and Ernst Mayr; however, virtually all evolutionary biologists and most textbooks supported these ideas until the late 1980s. In what follows, I discuss each of Coyne's points in turn.