Universität zu Köln

Hwang, Sungmin, Park, Su-Chan and Krug, Joachim ORCID: 0000-0002-2143-6490 (2017). Genotypic Complexity of Fisher's Geometric Model. Genetics, 206 (2). S. 1049 - 1080. BETHESDA: GENETICS SOCIETY AMERICA. ISSN 1943-2631

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Abstract

Fisher's geometric model was originally introduced to argue that complex adaptations must occur in small steps because of pleiotropic constraints. When supplemented with the assumption of additivity of mutational effects on phenotypic traits, it provides a simple mechanism for the emergence of genotypic epistasis from the nonlinear mapping of phenotypes to fitness. Of particular interest is the occurrence of reciprocal sign epistasis, which is a necessary condition for multipeaked genotypic fitness landscapes. Here we compute the probability that a pair of randomly chosen mutations interacts sign epistatically, which is found to decrease with increasing phenotypic dimension n, and varies nonmonotonically with the distance from the phenotypic optimum. We then derive expressions for the mean number of fitness maxima in genotypic landscapes comprised of all combinations of L random mutations. This number increases exponentially with L, and the corresponding growth rate is used as a measure of the complexity of the landscape. The dependence of the complexity on the model parameters is found to be surprisingly rich, and three distinct phases characterized by different landscape structures are identified. Our analysis shows that the phenotypic dimension, which is often referred to as phenotypic complexity, does not generally correlate with the complexity of fitness landscapes and that even organisms with a single phenotypic trait can have complex landscapes. Our results further inform the interpretation of experiments where the parameters of Fisher's model have been inferred from data, and help to elucidate which features of empirical fitness landscapes can be described by this model.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Hwang, Sungmin UNSPECIFIED UNSPECIFIED UNSPECIFIED Park, Su-Chan UNSPECIFIED UNSPECIFIED UNSPECIFIED Krug, Joachim UNSPECIFIED orcid.org/0000-0002-2143-6490 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-228997
DOI:	10.1534/genetics.116.199497
Journal or Publication Title:	Genetics
Volume:	206
Number:	2
Page Range:	S. 1049 - 1080
Date:	2017
Publisher:	GENETICS SOCIETY AMERICA
Place of Publication:	BETHESDA
ISSN:	1943-2631
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Physics > Institut für Biologische Physik
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language EMPIRICAL FITNESS LANDSCAPES; ADAPTIVE WALKS; POPULATION-GENETICS; SIGN EPISTASIS; ADAPTATION; MUTATIONS; PREDICTABILITY; EVOLUTION; COST Multiple languages Genetics & Heredity Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/22899