Fig. 6: Relationship between genetics and ecology illustrated on fatty acid adaptive landscapes. a, Different genetic mechanisms underlying increases in metabolic enzymatic activities. The arrow thickness indicates the gene expression levels. Gray circles and yellow asterisks indicate enzymes with ancestral and new functions, respectively. b, Effects of mutations on the metabolic pathways. Because of a pleiotropic effect of the enzyme, both metabolic pathways can be influenced. Font sizes reflect the amounts of synthesized fatty acids X and Y. Px, precursor of fatty acid X; Py, precursor of fatty acid Y. c, Adaptive (black) or non-adaptive walks (gray) on two different types of adaptive landscapes. The X and Y axes indicate the levels of fatty acids X and Y. Plus (+) indicates the adaptive peak. In Environment A, simultaneous increases of fatty acids X and Y are favored. In Environment B, however, only an increase in fatty acid X but not fatty acid Y is favored.