Variation in constraint versus positive selection as an explanation for evolutionary rate variation among anthocyanin genes.


Journal Article

It has been argued that downstream enzymes in metabolic pathways are expected to be subject to reduced selective constraint, while upstream enzymes, particularly those at pathway branch points, are expected to exhibit more frequent adaptive substitution than downstream enzymes. We examined whether these expectations are met for enzymes in the anthocyanin biosynthetic pathway in Ipomoea. Previous investigations have demonstrated that downstream enzymes in this pathway have substantially higher rates of nonsynonymous substitution than upstream enzymes. We demonstrate here that the difference in rates between the most upstream enzyme (CHS) and the two most downstream enzymes (ANS and UFGT) is explained almost entirely by differences in levels of selective constraint. Adaptive substitutions were not detected in any of these genes. Our results are consistent with suggestions that constraint is greater on enzymes with greater connectivity.

Full Text

Duke Authors

Cited Authors

  • Rausher, MD; Lu, Y; Meyer, K

Published Date

  • August 2008

Published In

Volume / Issue

  • 67 / 2

Start / End Page

  • 137 - 144

PubMed ID

  • 18654810

Pubmed Central ID

  • 18654810

Electronic International Standard Serial Number (EISSN)

  • 1432-1432

International Standard Serial Number (ISSN)

  • 0022-2844

Digital Object Identifier (DOI)

  • 10.1007/s00239-008-9105-5


  • eng