Comparative Functional Analyses of Mixotrophy among Microbial Eukaryotes
The ability of many single-celled, eukaryotes (protists) to combine photosynthetic and heterotrophic nutrition in a single cell is well established, but the phylogenetic breadth and tremendous ecological significance of this behavior is not widely acknowledged. ‘Mixotrophy’ is pervasive evolutionarily and ecologically. Mixotrophic behavior ranges from heterotrophic supplementation of predominantly phototrophic nutrition, to phototrophic survival of predominantly heterotrophic species under food-limited conditions, but a complex mixture of behaviors exists between these extremes. Specific benefits of heterotrophy in mixotrophic algae include the acquisition via phagotrophy or osmotrophy of carbon, energy, major nutrients (N,P) and various micronutrients (e.g. vitamins, metals, specific lipids) that provide these species with a competitive advantage over purely autotrophic species.