Paraphyly of organelle DNAs in Cycas Sect. Asiorientales due to ancient ancestral polymorphisms

Yu Chung Chiang, Kuo Hsiang Hung, Shann Jye Moore, Xue Jun Ge, Shong Huang, Tsai Wen Hsu*, Barbara A. Schaal, Ty Chiang

*此作品的通信作者

研究成果: 雜誌貢獻期刊論文同行評審

53 引文 斯高帕斯(Scopus)

摘要

Background. This study addresses the apportionment of genetic diversity between Cycas revoluta and C. taitungensis, species that constitute the section Asiorientales and represent a unique, basal lineage of the Laurasian genus Cycas. Fossil evidence indicates divergence of the section from the rest of Cycas at least 30 million years ago. Geographically, C. taitungensis is limited to Taiwan whereas C. revoluta is found in the Ryukyu Archipelago and on mainland China. Results. The phylogenies of ribosomal ITS region of mtDNA and the intergenic spacer between atpB and rbcL genes of cpDNA were reconstructed. Phylogenetic analyses revealed paraphyly of both loci in the two species and also in the section Asiorientales. The lack of reciprocal monophyly between these long isolated sections is likely due to persistent shared ancestral polymorphisms. Molecular dating estimated that mt- and cp DNA lineages coalesced to the most recent common ancestors (TMRCA) about 327 (mt) and 204 MYA (cp), corresponding with the divergence of cycad sections in the Mesozoic. Conclusion. Fates of newly derived mutations of cycads follow Klopfstein et al.'s surfing model where the majority of new mutations do not spread geographically and remain at low frequencies or are eventually lost by genetic drift. Only successful 'surfing mutations' reach very high frequencies and occupy a large portion of a species range. These mutations exist as dominant cytotypes across populations and species. Geographical subdivision is lacking in both species, even though recurrent gene flow by both pollen and seed is severely limited. In total, the contrasting levels between historical and ongoing gene flow, large population sizes, a long lifespan, and slow mutation rates in both organelle DNAs have all likely contributed to the unusually long duration of paraphyly in cycads.

原文英語
文章編號161
期刊BMC evolutionary biology
9
發行號1
DOIs
出版狀態已發佈 - 2009

ASJC Scopus subject areas

  • 生態學、進化論、行為學與系統學

指紋

深入研究「Paraphyly of organelle DNAs in Cycas Sect. Asiorientales due to ancient ancestral polymorphisms」主題。共同形成了獨特的指紋。

引用此