Directionality theory: an empirical study of an entropic principle in life‐history evolution

Abstract

Understanding the relationship between ecological constraints and life-history properties constitutes a central problem in evolutionary ecology. Directionality theory, a model of the evolutionary process based on demographic entropy, a measure of the uncertainty in the age of the mother of a randomly chosen newborn, provides an analytical framework for addressing this problem. The theory predicts that in populations that spend the greater part of their evolutionary history in the stationary growth phase (equilibrium species), entropy will increase. Equilibrium species will be characterized by high iteroparity and strong demographic stability. In populations that spend the greater part of their evolutionary history in the exponential growth phase (opportunistic species), entropy will decrease when population size is large, and will undergo random variation when population size is small. Opportunistic species will be characterized by weak iteroparity and weak demographic stability when population size is large, and random variations in these attributes when population size is small. This paper assesses the validity of these predictions by employing a demographic dataset of 66 species of perennial plants. This empirical analysis is consistent with directionality theory and provides support for its significance as an explanatory and predictive model of life-history evolution.

Taking sociality seriously: the structure of multi-dimensional social networks as a source of information for individuals

“…The advantage of considering this latter structural source of information is that it can be readily estimated as Shannon entropy [44]. As is well known, Shannon extended the thermodynamic concept of entropy to communication [44] and, since then, it has been applied in many fields as a measure of uncertainty [45]. The entropy of an interaction network is a measure that integrates behavioural consistency (and hence uncertainty reduction) across all individuals in the network, in a probabilistic fashion, because the links (known formally as edges) in the network represent the probability that two individuals will interact [46].…”

“…Significantly, this means that, if we view the global social network as a system that carries benefits for the individuals that comprise the network, then we can expect selection to act on social behaviour in ways that maintain and/or restore the topology of the network in the face of perturbation [45,53,54]. This is because perturbations to the social network will increase uncertainty: the potential outcomes of interactions in various behavioural contexts will be more difficult to predict because the social network structure has moved away from its stable state.…”

Inevitable evolution: back toThe Originand beyond the 20th Century paradigm of contingent evolution by historical natural selection

“…Lamarck (1809) proposed that organisms are driven towards higher levels of perfection, Cope (1871Cope ( , 1887 and Bonner (1988) that there is an increase in the complexity and size of organisms, and Fisher (1930) that the average fitness as represented by the intrinsic Malthusian parameter can only increase over time. Demetrius (1974) argued that demographic entropy will continue to increase for organisms at population dynamic equilibrium (see also Kowald and Demetrius 2005;Ziehe and Demetrius 2005;Bulmer 2006), Vermeij (1987) that organisms become more energy insensitive through evolutionary "arms races", and Maynard Smith and Szathmáry (1995) that hierarchical complexity has increased in a series of major life-history transitions where 'entities that were capable of independent replication before the transition can replicate only as part of a larger whole after it' (p. 4).…”

Thermodynamic Formulation of Living Systems and Their Evolution

“…For the phylogenic processes entropy production is associated to a collective, thus the evolutive processes are established at this time scale. Thermodynamically, the evolution of living matter is described by postulating the validity of the negentropy principle [44], which establishes that the evolution of biological systems occurs in the direction [45] that the structure [46] becomes more complex. That is, the phylogenic changes occur in the direction that the negentropy of the structure increases.…”