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Karyotype variation and evolution in populations of the Chinese endemic Orychophragmus violaceus complex (Brassicaceae)
Author(s) -
Zhou Lirong,
Liu Zhibin,
Wu Jun,
Wang Jianmei,
Yang Yi,
Li Xufeng
Publication year - 2008
Publication title -
nordic journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.333
H-Index - 33
eISSN - 1756-1051
pISSN - 0107-055X
DOI - 10.1111/j.1756-1051.2008.00242.x
Subject(s) - biology , indumentum , botany , brassicaceae , population , karyotype , taxon , chromosome , genetics , sociology , gene , demography
The karyological variation and cytogeography of the Orychophragmus violaceus complex from 15 locations across China has been studied to elucidate the evolutionary relationships amongst several chromosomal cytotypes. The results show that chromosomal variation within the complex is larger than previously thought, with three base numbers being identified: x=10 ( Orychophragmus diffuses ), 11 ( Orychophragmus hupehensis ) and 12 ( Orychophragmus taibaiensis and Orychophragmus violaceus ). For the first time, a tetraploid population of O. taibaiensis based on x=12 has been found. Two base numbers x=10 and x=12 may represent the ancestral condition of the O. violaceus complex. A progressive increase in chromosome number, decrease in intra‐chromosomal asymmetry, and appearance of tetraploidy is shown to be some of the most significant karyological changes associated with an increase in altitude of habitat. It is hypothesized that a center of differentiation is situated between the upper to mid Chang Jiang River and the Qin Mountain, where several biogeographic events involving recent evolutionary radiation have taken place.