ABSTRACT

The world as we perceive it is three dimensional. Physicists currently believe one needs on the order of a dozen dimensions to explain physical world. However, biological evolution occurs in a space with millions dimensions. Sewall Wright's powerful metaphor of rugged adaptive landscapes with its emphasis on adaptive peaks and valleys is based on analogies coming from our three-dimensional experience. Because the properties of multidimensional adaptive landscapes are very different from those of low dimension, for many biological questions Wright's metaphor is not useful or is even misleading. A new unifying framework that provides a plausible multidimensional alternative to the conventional view of rugged adaptive landscapes is emerging for deepening our understanding of evolution and speciation. The focus of this framework are percolating (nearly) neutral networks of well-fit genotypes which appear to be a common feature of genotype spaces of high dimensionality. A variety of important evolutionary questions have been approached using the new framework.

TABLE OF CONTENTS

• Abstract
  
• The problem of speciation
  
• Rugged adaptive landscapes
  
• Nearly neutral networks and holey adaptive landscapes
  
  • The origin of the idea
    
  • Simple models
    • Russian roulette model
    • Uniformly rugged landscape
    • Multiplicative fitnesses
    • Stabilizing selection on an additive trait
    • NK model
    • Conclusions from models
  • Experimental evidence
    
  • A metaphor of holey adaptive landscapes
    
• Applications
  • Genetic divergence and molecular evolution
    
  • Speciation
    
  • Adaptation
    
  • Hybrid zones
    
  • RNA and proteins
    
  • Gene and genome duplication
    
  • Canalization of development
    
  • Morphological macroevolution
    
• Conclusion
  
• Acknowledgments
  
• References