Multiple autopolyploidizations and range expansion of Allium przewalskianum Regel. (Alliaceae) in the Qinghai‐Tibetan Plateau |
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Authors: | LI‐LI WU XIE‐KUI CUI RICHARD I MILNE YONG‐SHUAI SUN JIAN‐QUAN LIU |
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Institution: | 1. Molecular Ecology Group, Key Laboratory of Arid and Grassland Ecology, School of Life Science, Lanzhou University, Lanzhou, 730000, China;2. Institute of Molecular Plant Sciences, The University of Edinburgh, Daniel Rutherford Building, King’s Buildings, Mayfield Road, Edinburgh EH9 3JH, UK;3. Royal Botanic Garden, Edinburgh, 20a Inverleith Row, Edinburgh EH3 5LR, UK |
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Abstract: | We used the Allium przewalskianum diploid–tetraploid complex on the Qinghai‐Tibetan Plateau (QTP) as a model to examine how this complex responded to the Quaternary climatic oscillations, and whether multiple autopolyploidizations have occurred. We sequenced five chloroplast DNA (cpDNA) fragments (accD‐psaI, trnH‐psbA, trnL‐trnF, trnS‐trnG and rpl16‐intron) in 306 individuals (all of known ploidy level) from 48 populations across the distribution of this species complex. We identified a total of 32 haplotypes—11 in diploids only, 13 in tetraploids only, and 8 found in both cytotypes. This, plus network analyses, indicated that tetraploids have arisen independently from diploids at least eight times. Most populations in the eastern QTP contained multiple haplotypes, but only a single haplotype was found for 17 tetraploid populations on the western QTP, suggesting a recent colonization of the western QTP. We further found that this species complex underwent an earlier range expansion around 5–150 thousand years ago (kya), after the largest glacial period (800–170 kya) in the QTP. In addition, the high frequencies of tetraploids in the QTP suggested that the tetraploid A. przewalskianum cytotype has evolutionary advantages over diploids in colonizing and/or surviving the arid habitats of the QTP. |
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Keywords: | Allium przewalskianum multiple origins polyploidization range expansion |
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