Gossmann et al. 2010
Fri May 14 2010
Genome wide analyses reveal little evidence for adaptive evolution in many plant species
The relative contribution of advantageous and neutral mutations to the evolutionary process is a central problem in evolutionary biology. Current estimates suggest that while Drosophila, mice and bacteria have undergone extensive adaptive evolution, hominids show little or no evidence of adaptive evolution in protein coding sequences. This may be a consequence of differences in effective population size. To study the matter further we have investigated whether plants show evidence of adaptive evolution using an extension of the McDonald-Kreitman test that explicitly models slightly deleterious mutations by estimating the distribution of fitness effects of new mutations. We apply this method to data from 9 pairs of species. Altogether more than 2400 loci with an average length of 280 nucleotides were analyzed. We observe very similar results in all species; we find little evidence of adaptive amino acid substitution in any comparison except sunflowers. This may be because many plant species have modest effective population sizes.
The relative contribution of advantageous and neutral mutations to the evolutionary process is a central problem in evolutionary biology. Current estimates suggest that while Drosophila, mice and bacteria have undergone extensive adaptive evolution, hominids show little or no evidence of adaptive evolution in protein coding sequences. This may be a consequence of differences in effective population size. To study the matter further we have investigated whether plants show evidence of adaptive evolution using an extension of the McDonald-Kreitman test that explicitly models slightly deleterious mutations by estimating the distribution of fitness effects of new mutations. We apply this method to data from 9 pairs of species. Altogether more than 2400 loci with an average length of 280 nucleotides were analyzed. We observe very similar results in all species; we find little evidence of adaptive amino acid substitution in any comparison except sunflowers. This may be because many plant species have modest effective population sizes.