Adaptive Landscapes

Abstract

In 1932, Sewall Wright used adaptive landscapes to illustrate his recently proposed shifting balance theory of evolution. He described evolutionary change as the movement of populations across high-dimensional landscapes of peaks and valleys, where elevation represented fitness levels. As envisioned by Wright, adaptive landscapes could consist of many thousands of peaks of various elevations separated by valleys and saddles of low fitness. Adaptive evolution of populations on this landscape translates into local hill climbing, and he argued that shifts from lower to higher peaks can only occur through fitness reductions as populations traverse valleys or saddles. More recently, two theoretical critiques to Wright’s assumption that fitness valleys would impede natural selection have been advanced. Nevertheless, Wright’s adaptive landscape remains influential because it continues to yield novel, theoretical, and experimental progress.