Individual Sensing can Gain more Fitness than its Information

TL;DR

This paper demonstrates that individual sensing can provide greater evolutionary fitness benefits than mutual or directed information, emphasizing the role of selection and chance in biological information processing.

Contribution

It introduces a new measure of fitness gain from individual sensing, showing it surpasses mutual information, and establishes fluctuation relations for this gain in evolutionary contexts.

Findings

Individual sensing yields higher fitness than mutual information.

A new quantity quantifies total fitness gain satisfying fluctuation relations.

Numerical verifications support the theoretical results.

Abstract

Mutual information and its causal variant, directed information, have been widely used to quantitatively characterize the performance of biological sensing and information transduction. However, once coupled with selection in response to decision-making, the sensing signal could have more or less evolutionary value than its mutual or directed information. In this work, we show that an individually sensed signal always has a better fitness value, on average, than its mutual or directed information. The fitness gain, which satisfies fluctuation relations (FRs), is attributed to the selection of organisms in a population that obtain a better sensing signal by chance. A new quantity, similar to the coarse-grained entropy production in information thermodynamics, is introduced to quantify the total fitness gain from individual sensing, which also satisfies FRs. Using this quantity, the optimizing fitness gain from individual sensing is shown to be related to fidelity allocations for individual environmental histories. Our results are supplemented by numerical verifications of FRs, and a discussion on how this problem is linked to information encoding and decoding.