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posted 01. May 2002 14:41
Proc. Natl. Acad. Sci. USA, Vol. 99, Issue 9, 6118-6123, April 30, 2002
Intron evolution as a population-genetic process
by Michael Lynch
Abstract: Debate over the mechanisms responsible for the phylogenetic and genomic distribution of introns has proceeded largely without consideration of the population-genetic forces influencing the establishment and retention of novel genetic elements. However, a simple model incorporating random genetic drift and weak mutation pressure against intron-containing alleles yields predictions consistent with a diversity of observations: (i) the rarity of introns in unicellular organisms with large population sizes, and their expansion after the origin of multicellular organisms with reduced population sizes; (ii) the relationship between intron abundance and the stringency of splice-site requirements; (iii) the tendency for introns to be more numerous and longer in regions of low recombination; and (iv) the bias toward phase-0 introns. This study provides a second example of a mechanism whereby genomic complexity originates passively as "pathological" response to small population size, and raises difficulties for the idea that ancient introns played a major role in the origin of genes by exon shuffling.
[ 01 May 2002, 14:43: Message edited by: Moderator ]
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