Towards a Comprehensive Dynamics of Evolution-
Exploring the Interplay of
Selection, Neutrality, Accident, and Function

5 - 9 October 1998
Santa Fe Institute
Santa Fe, New Mexico

Organized by
Jim Crutchfield, Santa Fe Institute
and
Peter Schuster, University of Vienna

Sponsored by The Santa Fe Institute

Synopsis

Evolution is currently addressed at very different levels from paleontology to molecular biology and even computer science. Common phenomena and common problems relate the different areas across this wide range. Examples include stepwise rather than gradual time courses of evolutionary adaptation, the role of selectively neutral variants in optimization, the destabilization of evolutionary memory as a function of parameters (error thresholds), the emergence of dynamical behaviors induced by finite populations, and the lack of a theory for genotype-phenotype relations and for emergent functionality. New paradigms and metaphors---e.g. self-organization, complex adaptive systems, phase transitions, and stochastic dynamical systems---may help to achieve progress and, hopefully, a new level of integration in analyzing such problems.

The workshop will bring together researchers from different disciplines as well as individuals of conflicting views on open problems in order to stimulate and provoke multifocused discussions. It is hoped that a synthesis of conflicting views---such as those of selectionists, neutralists, and structuralists or those of macroevolutionists and microevolutionists---will shed new light on our understanding of evolutionary dynamics. A primary goal is to help articulate a comprehensive dynamical theory that incorporates on an equal footing structural constraints, variational attainability, nonlinear population dynamics, neutrality, function, modularity, and other constituent aspects of the evolutionary process.

The work portion of the workshop will critically review the current, sometimes unformalized, proposals and recent theoretical progress. It will then assess what extensions and new concepts will be needed to address a number of concrete, but open problems, such as the following.
  • What are the limits of the metaphor of adaptive landscapes in evolution? When can one employ the geographic metaphor of "landscapes" rather than the full nonlinear population dynamics?
  • How do dynamical natural kinds arise in evolution and how robust are they to historical contingency?
  • What are the roles of energetic and entropic barriers in evolutionary adaptation? Are episodic evolutionary events common at all scales?
  • Are some classes of self-organization phenomena central to the evolutionary process? Which kinds of evidence need to be assembled to better test theories of self-organization?
  • How do the developmental dynamics of self-organization guide and constrain the nonlinear population dynamics of selection and genetic variation?
  • What classes of phenotypic degeneracy lead to neutral genetic variation? What is the role of neutrality in macroevolution? Is there a typology of neutral nets and innovation channels?
  • Generalized error thresholds: What are the trade-offs and scaling relationships between genome complexity, rate of genetic variation, and population size, for example?
  • In settings with complicated genotype-to-phenotype mappings, How can we find the macroscopic coordinates relevant to adaptation and search during a given evolutionary epoch?
  • How do the global state space structures induced by nonlinear population dynamics interact with the coarse-graining and stochasticity arising from finite populations?
One useful product of this exercise would be the creation of a number of tractable theoretical models, designed to capture the interplay of evolution's underlying features---selection, neutrality, fixation, accident, genotype-phenotype complexity, and phenotypic function. Another would be an assessment of which questions are tractable and timely. It is also hoped that the models and questions would suggest new experiments and new methods of data collection and analysis.




Jim Crutchfield
Last modified: 13 August 1998