Did genetic drift drive increases in genome complexity?

Mechanisms underlying the dramatic patterns of genome size variation across the tree of life remain mysterious. Effective population size (N(e)) has been proposed as a major driver of genome size: selection is expected to efficiently weed out deleterious mutations increasing genome size in lineages...

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Bibliographic Details
Published in:PLoS genetics 2010-08, Vol.6 (8), p.e1001080
Main Authors: Whitney, Kenneth D, Garland, Jr, Theodore
Format: Article
Language:English
Subjects:
Analysis
Animals
Bacteria - classification
Bacteria - genetics
Comparative analysis
Eukaryota - classification
Eukaryota - genetics
Evolution
Evolution, Molecular
Evolutionary Biology
Evolutionary Biology/Evolutionary and Comparative Genetics
Flowers & plants
Fungi - classification
Fungi - genetics
Genetic aspects
Genetic Drift
Genetics and Genomics
Genetics and Genomics/Population Genetics
Genome
Genomes
Genomics
Humans
Introns
Measurement
Microbiology
Models, Genetic
Mutation
Phylogeny
Transposons
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Summary:Mechanisms underlying the dramatic patterns of genome size variation across the tree of life remain mysterious. Effective population size (N(e)) has been proposed as a major driver of genome size: selection is expected to efficiently weed out deleterious mutations increasing genome size in lineages with large (but not small) N(e). Strong support for this model was claimed from a comparative analysis of N(e)u and genome size for ≈30 phylogenetically diverse species ranging from bacteria to vertebrates, but analyses at that scale have so far failed to account for phylogenetic nonindependence of species. In our reanalysis, accounting for phylogenetic history substantially altered the perceived strength of the relationship between N(e)u and genomic attributes: there were no statistically significant associations between N(e)u and gene number, intron size, intron number, the half-life of gene duplicates, transposon number, transposons as a fraction of the genome, or overall genome size. We conclude that current datasets do not support the hypothesis of a mechanistic connection between N(e) and these genomic attributes, and we suggest that further progress requires larger datasets, phylogenetic comparative methods, more robust estimators of genetic drift, and a multivariate approach that accounts for correlations between putative explanatory variables.
ISSN:1553-7404
1553-7390
1553-7404
DOI:10.1371/journal.pgen.1001080