Contrasting selection modes at Adh1 locus in outcrossing Miscanthus sinensis vs. inbreeding M. condensatus (Poaceae)

in International Symposium (poster summary), 國際研討會(摘要海報發表)
標題Contrasting selection modes at Adh1 locus in outcrossing Miscanthus sinensis vs. inbreeding M. condensatus (Poaceae)
出版類型國際研討會(摘要海報發表)
出版年度2001
AuthorsYu-Chung Chiang, 江友中
出版日期Nov 10 2001 12:0
會議地點高雄
其他編號0000
中文摘要

We estimated DNA sequence variation of the Adh1 locus in the outcrossing Miscanthus sinensis (Poaceae) and its close selfing relative, M. condensatus. Tajima’s test of selection is significantly negative for both overall exons and replacement sites in M. sinensis. Among its entire sample, nucleotide diversity of nonsynonymous sites is higher than that of synonymous sites. A McDonald and Kreitman test of neutrality indicates an excess of intraspecific replacement polymorphisms, suggesting possible directional selection toward advantageous mutants. However, frequent intragenic recombination suggests both purifying and positive selection is unlikely. Recent demographic expansions coupled with relaxation of purifying selection may have resulted in elevated genetic diversity at the Adh1 locus as well as the trnL-trnF intergenic spacer of cpDNA in this outcrossing species. In contrast, low levels of genetic diversity
were detected at both the Adh1 locus and the cpDNA spacer in M. condensatus, consistent with bottlenecks associated with selfing in all populations. While Tajima’s D and Fu and Li’s F statistics did not reveal deviation from neutrality at the Adh1 locus in M. condensatus, 12 replacements vs. 10 synonymous changes were detected. Based on pairwise comparisons of the dN/dS ratio, lineages of closely related populations of the species distributed along saline habitats appeared to be under directional selection.

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