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Variation within and among species in gene expression: raw material for evolution
Author(s) -
WHITEHEAD ANDREW,
CRAWFORD DOUGLAS L.
Publication year - 2006
Publication title -
molecular ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.619
H-Index - 225
eISSN - 1365-294X
pISSN - 0962-1083
DOI - 10.1111/j.1365-294x.2006.02868.x
Subject(s) - biology , evolutionary biology , variation (astronomy) , divergence (linguistics) , gene , context (archaeology) , genetics , selection (genetic algorithm) , genetic variation , dna microarray , human evolutionary genetics , phylogenetics , gene expression , paleontology , philosophy , linguistics , physics , artificial intelligence , astrophysics , computer science
Heritable variation in regulatory or coding regions is the raw material for evolutionary processes. The advent of microarrays has recently promoted examination of the extent of variation in gene expression within and among taxa and examination of the evolutionary processes affecting variation. This review examines these issues. We find: (i) microarray‐based measures of gene expression are precise given appropriate experimental design; (ii) there is large inter‐individual variation, which is composed of a minor nongenetic component and a large heritable component; (iii) variation among populations and species appears to be affected primarily by neutral drift and stabilizing selection, and to a lesser degree by directional selection; and (iv) neutral evolutionary divergence in gene expression becomes nonlinear with greater divergence times due to functional constraint. Evolutionary analyses of gene expression reviewed here provide unique insights into partitioning of regulatory variation in nature. However, common limitations of these studies include the tendency to assume a linear relationship between expression divergence and species divergence, and failure to test explicit hypotheses that involve the ecological context of evolutionary divergence.