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Keywords:

  • Clusia;
  • crassulacean acid metabolism (CAM);
  • ecophysiology;
  • neotropics;
  • plasticity;
  • photosynthesis;
  • phylogeny

Contents

  •  Summary 7

  • I. 
    The discovery of crassulacean acid metabolism (CAM) in the trees of Clusia: arrival in the limelight of international research 8
  • II. 
    Phylogeny 8
  • III. 
    Photosynthetic physiotypes 10
  • IV. 
    Metabolic flexibility: organic acid variations 12
  • V. 
    The environmental control of photosynthetic flexibility 13
  • VI. 
    Phenotypic plasticity: physiotypes and morphotypes 16
  • VII. 
    Ecological amplitude and habitat impact 16
  • VIII. 
    Conclusions and outlook 21
  •  Acknowledgements 22

  •  References 22

Summary

It is the aim of this review to present a monographic survey of the neotropical genus Clusia on scaling levels from molecular phylogeny, metabolism, photosynthesis and autecological environmental responses to ecological amplitude and synecological habitat impact. Clusia is the only dicotyledonous genus with real trees performing crassulacean acid metabolism (CAM). By way of introduction, a brief historical reminiscence describes the discovery of CAM in Clusia and the consequent increase in interest in studying this particular genus of tropical shrubs and trees. The molecular phylogeny of CAM in the genus is compared with that in Kalanchoë and the Bromeliaceae. At the level of metabolism and photosynthesis, the great plasticity of expression of photosynthetic physiotypes, i.e. (i) C3 photosynthesis, (ii) CAM including CAM idling, (iii) CAM cycling and (iv) C3/CAM-intermediate behaviour, as well as metabolic flexibility in Clusia is illustrated. At the level of autecology, the factors water, irradiance and temperature, which control photosynthetic flexibility, are assessed. The phenotypic plasticity of physiotypes and morphotypes is described. At the level of synecology, the ecological amplitude of Clusia in the tropics and the relations to habitat are surveyed.