On the Possibility of Constructive Neutral Evolution |
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Authors: | Arlin Stoltzfus |
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Institution: | (1) Department of Biochemistry, Dalhousie University, Halifax, Nova Scotia, B3H 4H7 Canada, CA |
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Abstract: | The neutral theory often is presented as a theory of ``noise' or silent changes at an isolated ``molecular level,' relevant
to marking the steady pace of divergence, but not to the origin of biological structure, function, or complexity. Nevertheless,
precisely these issues can be addressed in neutral models, such as those elaborated here with regard to scrambled ciliate
genes, gRNA-mediated RNA editing, the transition from self-splicing to spliceosomal splicing, and the retention of duplicate
genes. All of these are instances of a more general scheme of ``constructive neutral evolution' that invokes biased variation,
epistatic interactions, and excess capacities to account for a complex series of steps giving rise to novel structures or
operations. The directional and constructive outcomes of these models are due not to neutral allele fixations per se, but
to these other factors. Neutral models of this type may help to clarify the poorly understood role of nonselective factors
in evolutionary innovation and directionality.
Received: 3 September 1998 / Accepted: 15 February 1999 |
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Keywords: | : Neutral evolution — Scrambling — RNA editing — Spliceosomal introns — Gene duplication — Complexity |
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