Multiple Fitness Peaks on the Adaptive Landscape Drive Adaptive Radiation in the Wild

Abstract

Pupfish Speciation Evolution moves along phenotypic trajectories that can be visualized as a topographic landscape of multiple peaks of relatively high-fitness and low-fitness valleys. Martin and Wainwright (p. 208 ) examined the adaptive landscape of three species of Cyprinodon pupfishes. These species represent a recent adaptive radiation, each having moved into a difference niche within their specialized environment. Examining replicate hybrid transplants relative to parental types in high- and low-density enclosures, the authors recovered the specialist parental phenotypes and observed higher survival and growth. Thus, high density can drive multiple fitness peaks during the early stages of adaptive radiation.