Consistent metabolic behaviours and their evolutionary trait. (Left) The frequency of appearance of the central and the non-central mutants over the 58 different carbon-source conditions (empty black circles and empty green squares respectively). Redundant nodes in some growth conditions can be central mutants in other conditions. The most frequently-appearing highly central mutants are highlighted (filled colored circles). (Right) The gene conservation density is shown for each strain. Environmental-invariant strain-hubs correspond to gene deletions in more conserved genes relative to environmental-specific hubs. Similarly, environment-invariant redundant strains correspond to deletions in less conserved genes than the environment-specific redundant strains. This finding implies that a polymorphic strain community is more likely to evolve if it consists mainly of environment-specific strains as they are evolutionary more stable.