dorsal/arxiv
View SchemaChance and Necessity in Evolution: Lessons from RNA
| Authors | Peter Schuster, Walter Fontana |
|---|---|
| Categories | |
| ArXiv ID | physics/9811037 |
| URL | https://arxiv.org/abs/physics/9811037 |
| DOI | 10.1016/S0167-2789(99)00076-7 |
Abstract
The relationship between sequences and secondary structures or shapes in RNA exhibits robust statistical properties summarized by three notions: (1) the notion of a typical shape (that among all sequences of fixed length certain shapes are realized much more frequently than others), (2) the notion of shape space covering (that all typical shapes are realized in a small neighborhood of any random sequence), and (3) the notion of a neutral network (that sequences folding into the same typical shape form networks that percolate through sequence space). Neutral networks loosen the requirements on the mutation rate for selection to remain effective. The original (genotypic) error threshold has to be reformulated in terms of a phenotypic error threshold. With regard to adaptation, neutrality has two seemingly contradictory effects: It acts as a buffer against mutations ensuring that a phenotype is preserved. Yet it is deeply enabling, because it permits evolutionary change to occur by allowing the sequence context to vary silently until a single point mutation can become phenotypically consequential. Neutrality also influences predictability of adaptive trajectories in seemingly contradictory ways. On the one hand it increases the uncertainty of their genotypic trace. At the same time neutrality structures the access from one shape to another, thereby inducing a topology among RNA shapes which permits a distinction between continuous and discontinuous shape transformations. To the extent that adaptive trajectories must undergo such transformations, their phenotypic trace becomes more predictable.
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"abstract": "The relationship between sequences and secondary structures or shapes in RNA\nexhibits robust statistical properties summarized by three notions: (1) the\nnotion of a typical shape (that among all sequences of fixed length certain\nshapes are realized much more frequently than others), (2) the notion of shape\nspace covering (that all typical shapes are realized in a small neighborhood of\nany random sequence), and (3) the notion of a neutral network (that sequences\nfolding into the same typical shape form networks that percolate through\nsequence space). Neutral networks loosen the requirements on the mutation rate\nfor selection to remain effective. The original (genotypic) error threshold has\nto be reformulated in terms of a phenotypic error threshold. With regard to\nadaptation, neutrality has two seemingly contradictory effects: It acts as a\nbuffer against mutations ensuring that a phenotype is preserved. Yet it is\ndeeply enabling, because it permits evolutionary change to occur by allowing\nthe sequence context to vary silently until a single point mutation can become\nphenotypically consequential. Neutrality also influences predictability of\nadaptive trajectories in seemingly contradictory ways. On the one hand it\nincreases the uncertainty of their genotypic trace. At the same time neutrality\nstructures the access from one shape to another, thereby inducing a topology\namong RNA shapes which permits a distinction between continuous and\ndiscontinuous shape transformations. To the extent that adaptive trajectories\nmust undergo such transformations, their phenotypic trace becomes more\npredictable.",
"arxiv_id": "physics/9811037",
"authors": [
"Peter Schuster",
"Walter Fontana"
],
"categories": [
"physics.bio-ph",
"q-bio"
],
"doi": "10.1016/S0167-2789(99)00076-7",
"title": "Chance and Necessity in Evolution: Lessons from RNA",
"url": "https://arxiv.org/abs/physics/9811037"
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