Biological information: why we need a good measure and the challenges ahead

Abstract

Evolution can be characterized as a process that shapes and maintains information across generations. It is also widely acknowledged that information may play a pivotal role in many other ecological processes. Most of the ecologically relevant information (and some important evolutionary information too) is of a very subjective and analogue kind: individuals use cues that may carry information useful only to them but not to others. This is a problem because most information theory has been developed for objective and discrete information. Can information theory be extended to this theory to incorporate multiple forms of information, each with its own (physical) carriers and dynamics? Here, I will not review all the possible roles that information can play, but rather what conditions an appropriate theory should satisfy. The most promising starting point is provided by entropy measures of conditional probabilities (using the so-called Kullback–Leibler divergence), allowing an assessment of how acquiring information can lead to an increase in fitness. It is irrelevant (to a certain extent) where the information comes from—genes, experience or culture—but it is important to realize that information is not merely subjective but its value should be evaluated in fitness terms, and it is here that evolutionary theory has an enormous potential. A number of important stumbling points remain, however; namely, the identification of whose fitness it concerns and what role the spatio-temporal dynamics plays (which is tightly linked to the nature of the physical carriers of the information and the processes that impact on it).

Innovation: an emerging focus from cells to societies

“…[34] aims to address this problem by connecting evolutionary biology to information theory. Classical population genetics focuses on genotypes and the information encoded therein, but more recent work highlights the importance of phenotypes as gatherers and processors of environmental information [128]. Wagner employs information theory to quantify the information content of a phenotype and to investigate the feasibility of acquiring or 'discovering' novel and beneficial phenotypes.…”

Information theory, evolutionary innovations and evolvability

“…Evolutionary biologists have a long-standing interest in information theory, because it is ultimately information encoded in DNA that renders the survivors of natural selection well adapted to their environment [1][2][3][4]. Among the first researchers to explore the link between information and evolution was Motoo Kimura.…”

Information theory and the phenotypic complexity of evolutionary adaptations and innovations

“…In developmental biology, organisms execute "programs" as they develop from zygote to adult [2,4]. Information theory has also been attractive to evolutionary biologists [2,3,[5][6][7]. That's because the survivors of natural selection harbor genetically-encoded information about their environment.…”

“…Yet another example is the fraction of seeds that germinate in any one year in populations of desert annual plants. For optimal reproductive success, this phenotype needs to incorporate information about past rainfall patterns [5,[11][12][13][14][15][16][17][18][19][20][21].…”