The speciation and adaptation of the polyploids: a case study of the Chinese Isoetes L. diploid-polyploid complex

BMC Evolutionary Biology

Xiaokang Dai¹  Xiang Li¹  Yuqian Huang¹  Xing Liu² 

[1]Laboratory of Plant Systematics and Evolutionary Biology, College of Life Sciences, Wuhan University, 430072, Wuhan, Hubei, People’s Republic of China

[2]Laboratory of Plant Systematics and Evolutionary Biology, College of Life Sciences, Wuhan University, 430072, Wuhan, Hubei, People’s Republic of China

[3]College of Sciences, Tibet University, 850012, Lhasa, Tibet, People’s Republic of China

关键词: Allopolyploid;    Altitude;    Isoetes;    Distribute pattern;    Niche breadth;    Niche novelty;   

DOI  :  10.1186/s12862-020-01687-4

来源: Springer

【 摘 要 】

BackgroundThe Chinese Isoetes L. are distributed in a stairway pattern: diploids in the high altitude and polyploids in the low altitude. The allopolyploid I. sinensis and its diploid parents I. yunguiensis and I. taiwanensis is an ideal system with which to investigate the relationships between polyploid speciation and the ecological niches preferences.ResultsThere were two major clades in the nuclear phylogenetic tree, all of the populations of polyploid were simultaneously located in both clades. The chloroplast phylogenetic tree included two clades with different populations of the polyploid clustered with the diploids separately: I. yunguiensis with partial populations of the I. sinensis and I. taiwanensis with the rest populations of the I. sinensis. The crow node of the I. sinensis allopolyploid system was 4.43 Ma (95% HPD: 2.77–6.97 Ma). The divergence time between I. sinensis and I. taiwanensis was estimated to 0.65 Ma (95% HPD: 0.26–1.91 Ma). The narrower niche breadth in I.sinensis than those of its diploid progenitors and less niche overlap in the pairwise comparisons between the polyploid and its progenitors.ConclusionsOur results elucidate that I. yunguinensis and I. taiwanensis contribute to the speciation of I. sinensis, the diploid parents are the female parents of different populations. The change of altitude might have played an important role in allopolyploid speciation and the pattern of distribution of I. sinensis. Additionally, niche novelty of the allopolyploid population of I. sinensis has been detected, in accordance with the hypothesis that niche shift between the polyploids and its diploid progenitors is important for the establishment and persistence of the polyploids.

【 授权许可】

CC BY