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.