Alternative sources of information for adaptation to varying environments

Two types of adaptation strategies have been widely studied for organisms in varying environments. The "sensing" strategy assumes that organisms are able to gather information from the present environment and adapt their traits, thus maximizing their fitness at all times. The "bet-hedging" strategy, on the other hand, allows a population to survive by maintaining a diversity of traits among individuals, so that the average fitness is less affected by environmental fluctuation. Because the bet-hedging strategy does not make use of environmental information, it is expected to perform worse than the sensing strategy, unless the cost of gathering external information is prohibitive. Here, we demonstrate a different type of strategy that utilizes an internal source of information to improve performance. For example, an organism may choose to forage or not depending on how much energy reserve it has; the reserve level effectively serves as a memory of past environments. In general, the trait of an organism may depend on an internal state, which does not directly interact with the environment but becomes correlated with it due to past selection. We show that this strategy using internal information can outperform bet-hedging and even approach the sensing strategy.