Transfer and Origin of Adaptations through Natural Hybridization: Were Anderson and Stebbins Right?

Abstract

The biographer Ronald Clark once described the influential evolutionary mathematician J.B.S. Haldane as “…among the last of the ‘string-and-sealing-wax' scientists, the men who could achieve results by themselves, without the aid of a committee, and who could, without the help of another committee, see how their discoveries fitted into the larger pattern of scientific knowledge” (Clark, 1984). This sentiment is also true for the equally influential evolutionary botanists Ledyard Stebbins and Edgar Anderson. Indeed, the last decade has witnessed a renaissance of studies (e.g., Arnold, 1992, 1997, 2004; Grant and Grant, 1992, 2002; Dowling and DeMarais, 1993; Rieseberg, 1997; Rieseberg et al., 2003) into the evolutionary role of natural hybridization—for example, the natural interbreeding of individuals from wild populations that can be distinguished on the basis of one or more heritable characters (Harrison, 1990; Arnold, 1997)—the process explored and described extensively by these investigators (e.g., Anderson and Stebbins, 1954). Through new insights and investigations, the general conceptual framework proposed by these authors, that natural hybridization was evolutionarily creative through the origin of new species and adaptations (or the transfer of adaptations between the hybridizing forms), has been extended greatly in the last 10 years. However, just as the work of J.B.S. Haldane remains broadly applicable to evolutionary concepts (e.g., Haldane, 1948, 1949), so also do the original experimental and conceptual studies of Anderson and Stebbins (e.g., Anderson and Hubricht, 1938; Anderson, 1948, 1949; Stebbins, 1959).