Contrasting Patterns of Nucleotide Polymorphism at the Alcohol Dehydrogenase Locus in the Outcrossing Arabidopsis lyrata and the Selfing Arabidopsis thaliana

摘要: Nucleotide variation at the alcohol dehydrogenase locus (Adh) was studied in outcrossing Arabidopsis lyrata, a close relative of selfing thaliana. Overall, estimated nucleotide diversity North American ssp. lyrata and two European petraea populations 0.0038, lower than corresponding specieswide estimate for A. thaliana same set sites. The distribution segregating sites across gene differed between species. Estimated sequence within an population with large sample size (0.0023) much higher has previously been observed This excess intermediate frequencies compared neutral expectation (Tajima's D = 2.3, P < 0.005), suggestive linked balancing selection or recent bottleneck. In contrast, rare polymorphisms found Polymorphism divergence from appear to be correlated Adh sequence. geographic polymorphism quite different that thaliana, which earlier studies several genes low within-population site no overall continental differentiation despite differences local populations. Differences reflect impact mating system influence bottlenecks during rapid colonization on DNA polymorphism. additional variability-reducing mechanisms, such as background hitchhiking, may not discernible.