Molecular Evolution of the atpB-rbcL Noncoding Spacer of Chloroplast DNA in the Moss Family Hylocomiaceae

本研究探討葉綠體DNA中一個介於atpB及rbcL基因間的非轉譯區間在塔蘚科植物的分子演化，種間的遺傳變異大多來自核苷酸的置換，雖然一个29bp的插入發生在Rhytidiopsis robusta,atpB-rbcL基因區間的演化速率在塔蘚科中相較於被子植物中,或被子植物的rbcL基因還要緩慢，根據相對速率測驗，此DNA片段的演化符合分子時鐘的假說。依據在真蘚植物中已知的分子演化速度，塔蘚植物的起源可以推溯至二千九百萬年前，并與化石證據吻合。此基因片段支持塔蘚科植物為一單一起源的分類群，然而，在最大簡約分析中因長支吸引效應，使得Rhytidiopsis及Rhytidium發生錯誤的分類，相對地，相鄰連接分析在重建親綠歷史上有較可靠的估算。

關鍵字

atpB-rbcL基因間的區間片段；葉綠體DNA ；分子序列；基因樹；塔蘚科；長枝吸引；蘚類；分子時鐘

並列摘要

Molecular evolution of the chloroplast noncoding region between the atpB and rbcL genes was investigated in the moss family Hylocomiaceae. Nucleotide substitution contributed to most of the variation among taxa, although an insertion of 29 base pairs was found in Rhytidiopsis robusta. The evolution of atpB-rbcL intergenic spacer was constrained in Hylocomiaceae compared to the evolutionary rates of this chloroplast spacer, and even of the rbcL gene, in angiosperms. Using a relative rate test procedure, substitution rates of the chloroplast spacer were found to be consistent with the hypothesis of a molecular clock, except for three taxa. Based on previous knowledge of the evolutionary rate of this spacer in true mosses, the divergence of the Hylocomiaceae from their common ancestor was estimated to be 29.0 million years ago, which is consistent with the fossil record. The chloroplast sequences supported the monophyly of the Hylocomiaceae with a bootstrap value of 82%. The effects of long branch attraction caused the erroneous placements of Rhytidiopsis and Rhytidium in the parsimony analysis. In contrast, neighbor-joining analysis provided a more congruent estimate of the phylogeny of the Hylocomiaceae based on the cpDNA variation observed.

並列關鍵字

atpB-rbcL intergenic spacer ； Chloroplast DNA ； DNA sequence ； Gene tree ； Hylocomiaceae ； Long branch attraction ； Molecular clock ； Mosses

國際替代計量

Molecular Evolution of the atpB-rbcL Noncoding Spacer of Chloroplast DNA in the Moss Family Hylocomiaceae

全文下載

主題瀏覽