The end of the adaptive landscape metaphor?
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The concepts of adaptive/fitness landscapes and adaptive peaks are a central part of much of contemporary evolutionary biology; the concepts are introduced in introductory texts, developed in more detail in graduate-level treatments, and are used extensively in papers published in the major journals in the field. The appeal of visualizing the process of evolution in terms of the movement of populations on such landscapes is very strong; as one becomes familiar with the metaphor, one often develops the feeling that it is possible to gain deep insights into evolution by thinking about the movement of populations on landscapes consisting of adaptive valleys and peaks. But, since Wright first introduced the metaphor in 1932, the metaphor has been the subject of persistent confusion, from equivocation over just what the features of the landscape are meant to represent to how we ought to expect the landscapes to look. Recent advances—conceptual, empirical, and computational—have pointed towards the inadequacy and indeed incoherence of the landscapes as usually pictured. I argue that attempts to reform the metaphor are misguided; it is time to give up the pictorial metaphor of the landscape entirely and rely instead on the results of formal modeling, however difficult such results are to understand in ‘intuitive’ terms.
KeywordsAdaptive landscape Fitness landscape Wright Gavrilets Holey landscape Peak shift Shifting balance theory Bateson-Dobzhansky-Muller model Speciation Adaptation Metaphor
This paper is based in part on a book chapter co-written with Massimo Pigliucci (SUNY Stonybrook). Sergey Gavrilets was generous with his time in providing assistance in understanding his models and approaches. Massimo provided helpful feedback on earlier versions of this material, as did Sharyn Clough, Anya Plutynski, members of the UBC Philosophy Department, Department of Botany, and Department of Zoology, members of the University of Houston’s Department of Biology and Biochemistry, and participants in the 2006 Pacific APA mini-conference “Scientific Images.”
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