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

Proceedings: Biological Sciences
ISSN: 0962-8452 (Paper) 1471-2954 (Online)
Issue: Volume 272, Number 1568 / June 07, 2005

Pages: 1185 - 1194
DOI: 10.1098/rspb.2004.3032
URL: Linking Options
Directionality theory: an empirical study of an entropic principle in
life-history evolution

Martin Ziehe A1 and Lloyd Demetrius A2 A3
A1 Institut für Forstgenetik und Forstpflanzenzüchtung, Universität
Göttingen, Büsgenweg 2,37089 Göttingen, Germany
A2 Department of Organismic and Evolutionary Biology, Harvard University,
Cambridge, MA 02138, USA
A3 Max Planck Institute for Molecular Genetics, Ihnestraβe 71, 14195 Berlin,
Germany

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.

Full text at The Royal Society
http://tinyurl.com/9gs6p

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