New insights into polyploid evolution and dynamic nature of Ludwigia section Isnardia (Onagraceae)

Botanical Studies

Original Article

Ching-I Peng¹  Shih-Hui Liu²  Tzen-Yuh Chiang³  Tsai-Wen Hsu⁴  Kuo-Hsiang Hung⁵  Peter C. Hoch⁶ 

[1] Biodiversity Research Center, Academia Sinica, 11529, Taipei, Taiwan;Department of Biological Sciences, National Sun Yat-Sen University, 804, Kaohsiung, Taiwan;Department of Life Sciences, National Cheng Kung University, 701, Tainan, Taiwan;Endemic Species Research Institute, 552, Nantou, Taiwan;Graduate Institute of Bioresources, National Pingtung University of Science and Technology, 912, Pingtung, Taiwan;Missouri Botanical Garden, 63166, St. Louis, MO, USA;

关键词: Divergence time;    Genetic variation;    Hybridization;    Interspecific gene flow;    Polyploid evolution;   

DOI  :  10.1186/s40529-023-00387-8

 received in 2022-11-16, accepted in 2023-05-17,  发布年份 2023

来源: Springer

【 摘 要 】

BackgroundWhile polyploids are common in plants, the evolutionary history and natural dynamics of most polyploid groups are still unclear. Owing to plentiful earlier systematic studies, Ludwigia sect. Isnardia (comprising 22 wetland taxa) is an ideal allopolyploid complex to investigate polyploid evolution and natural dynamics within and among taxa. With a considerable sampling, we concentrated on revisiting earlier phylogenies of Isnardia, reevaluating the earlier estimated age of the most recent common ancestor (TMRCA), exploring the correlation between infraspecific genetic diversity and ploidy levels, and inspecting interspecific gene flows among taxa.ResultsPhylogenetic trees and network concurred with earlier phylogenies and hypothesized genomes by incorporating 192 atpB-rbcL and ITS sequences representing 91% of Isnardia taxa. Moreover, we detected three multi-origin taxa. Our findings on L. repens and L. sphaerocarpa were consistent with earlier studies; L. arcuata was reported as a multi-origin taxon here, and an additional evolutionary scenario of L. sphaerocarpa was uncovered, both for the first time. Furthermore, estimated Isnardia TMRCA ages based on our data (5.9 or 8.9 million years ago) are in accordance with earlier estimates, although younger than fossil dates (Middle Miocene). Surprisingly, infraspecific genetic variations of Isnardia taxa did not increase with ploidy levels as anticipated from many other polyploid groups. In addition, the exuberant, low, and asymmetrical gene flows among Isnardia taxa indicated that the reproductive barriers may be weakened owing to allopolyploidization, which has rarely been reported.ConclusionsThe present research gives new perceptions of the reticulate evolution and dynamic nature of Isnardia and points to gaps in current knowledge about allopolyploid evolution.

【 授权许可】

CC BY   
© The Author(s) 2023

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