Universität zu Köln

Schmiegelt, B. and Krug, J. (2014). Evolutionary Accessibility of Modular Fitness Landscapes. J. Stat. Phys., 154 (1-2). S. 334 - 356. NEW YORK: SPRINGER. ISSN 1572-9613

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Abstract

A fitness landscape is a mapping from the space of genetic sequences, which is modeled here as a binary hypercube of dimension L, to the real numbers. We consider random models of fitness landscapes, where fitness values are assigned according to some probabilistic rule, and study the statistical properties of pathways to the global fitness maximum along which fitness increases monotonically. Such paths are important for evolution because they are the only ones that are accessible to an adapting population when mutations occur at a low rate. The focus of this work is on the block model introduced by A.S. Perelson and C.A. Macken (Proc. Natl. Acad. Sci. USA 92:9657, 1995) where the genome is decomposed into disjoint sets of loci ('modules') that contribute independently to fitness, and fitness values within blocks are assigned at random. We show that the number of accessible paths can be written as a product of the path numbers within the blocks, which provides a detailed analytic description of the path statistics. The block model can be viewed as a special case of Kauffman's NK-model, and we compare the analytic results to simulations of the NK-model with different genetic architectures. We find that the mean number of accessible paths in the different versions of the model are quite similar, but the distribution of the path number is qualitatively different in the block model due to its multiplicative structure. A similar statement applies to the number of local fitness maxima in the NK-models, which has been studied extensively in previous works. The overall evolutionary accessibility of the landscape, as quantified by the probability to find at least one accessible path to the global maximum, is dramatically lowered by the modular structure.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Schmiegelt, B. UNSPECIFIED UNSPECIFIED UNSPECIFIED Krug, J. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-450828
DOI:	10.1007/s10955-013-0868-8
Journal or Publication Title:	J. Stat. Phys.
Volume:	154
Number:	1-2
Page Range:	S. 334 - 356
Date:	2014
Publisher:	SPRINGER
Place of Publication:	NEW YORK
ISSN:	1572-9613
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language RANDOM-ENERGY MODEL; SIGN EPISTASIS; SELECTION; PREDICTABILITY; ADAPTATION; WALKS Multiple languages Physics, Mathematical Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/45082