Cytogeography and chromosomal variation of the endemic East Asian herb Lycoris radiata

摘要

Information on the spatial distribution of cytotypes and karyotype variation in plants is critical for studies of the origin and evolution of polyploid complexes. Here, the spatial distribution of cytological races and intraspecific variation in the karyotype of Lycoris radiata , an endemic species to East Asia, is investigated. Conventional karyotype analysis methods were used to determine ploidy level and karyotypical characteristics in 2,420 individuals from 114 populations of L .? radiata nearly covering the whole distribution areas in China. Of 114 populations studied, 52 (45.61%), 58 (50.88%), and 4 (3.51%) are diploid, triploid, and mixoploid populations, respectively, with 1,224, 1,195, and 1 individuals being diploid, triploid, and tetraploid, respectively. The triploid possesses a much wider distribution range than the diploid, with the former almost occupying the entire range of this complex species in East Asia and the latter distributing in the middle and east regions of China. Triploids tend to occur at high altitudes, and the relationship between the ploidy and altitude is significantly positive but low ( r 2? =?0.103, p ??0.01). About 98.6% of examined bulbs have a common karyotype consisting of 22 or 33 acrocentric ( A ) chromosomes. Some aberrant chromosomes which should be generated from A‐type chromosome have been found including metacentrics ( m ), small metacentrics ( m ′), and B‐type chromosome. The results can provide a fundamental cytogeographic data for further studies on the evolutionary origins and adaptive divergences of polyploids, especially the triploid, within L .? radiata using molecular and/or ecological methods in the future.