DOI: 10.1101/510958Jan 3, 2019Paper

Molecular evolution in large steps - Codon substitutions under positive selection

BioRxiv : the Preprint Server for Biology
Qingjian ChenChung-I Wu

Abstract

Molecular evolution is believed to proceed in small steps. The step size can be defined by a distance reflecting physico-chemical disparities between amino acid (AA) pairs that can be exchanged by single 1 bp mutations. We show that AA substitution rates are strongly and negatively correlated with this distance but only when positive selection is relatively weak. We use the McDonald and Kreitman (MK) test to separate the influences of positive and negative selection. While negative selection is indeed stronger on AA substitutions generating larger changes in chemical properties of amino acids, positive selection operates by different rules. For 65 of the 75 possible pairs, positive selection is comparable in strength regardless of AA distance. However, the 10 pairs under the strongest positive selection all exhibit large leaps in chemical properties. Five of the 10 pairs are shared between hominoids and Drosophila, thus hinting at a common but modest biochemical basis of adaptation across taxa. The hypothesis that adaptive changes often take large functional steps will need to be extensively tested. If validated, molecular models will need to better integrate positive and negative selection in the search for adaptive signal.

Related Concepts

Drosophila
Chemicals
Evolution, Molecular
Adaptation
Size
Amino Acid Substitution
Macdonald's Cervical Cerclage
Codon Genus
Genus Homo
Adaptation of Signaling Pathway

Related Feeds

BioRxiv & MedRxiv Preprints

BioRxiv and MedRxiv are the preprint servers for biology and health sciences respectively, operated by Cold Spring Harbor Laboratory. Here are the latest preprint articles (which are not peer-reviewed) from BioRxiv and MedRxiv.

Related Papers

Molecular Biology and Evolution
Antonis Rokas, Sean B Carroll
Proceedings of the National Academy of Sciences of the United States of America
Joshua A ShapiroChung-I Wu
Health Services Journal
Jennifer Trueland
© 2021 Meta ULC. All rights reserved