从核型看北美红杉的起源

本文分析了同源异源自然六倍体北美红杉的AA和B染色体组的组型,它们属Stebbins的“1A”和“1B”,经与杉科各属植物的核型比较后发现分别与相同类型的水杉和巨杉最为接近,因而认为水杉属和巨杉属的某个古代种可能是北美红杉的二个杂交亲本,水杉和巨杉则或许是它们的后裔或近缘。本研究支持Stebbins认为水杉属的某个古代种是红杉的一个祖先而水杉是它的直接后裔的假设,但与他认为另一个祖先已经灭绝并没有留下近缘的推测存在分歧。

THE ORIGIN OF SEQUOIA SEMPERVIRENS (TAXODIACEAE) BASED ON KARYOTYPE

Sequoia sempervirens is an autoallopolyploid with the genomie formula AAAABB. Its complement-AA and -B, that belong to Stebbins' "1A" and "1B" karyotypic type respectively, are quite similar to the karyotypcs of Mctaxc-quoia glyptostroboides and Sequoiadendron qiqantcum (Table 1 , 2). So some ancient species of Metasequoia and Sequoiadendron may be the two hybrid parents of S. sempervirens, M. glyptostroboides and S. giganteum are probably direct descendants of them. The present study supports Stebbins' suggestion that one ancient species of Metasequoia would be an ancestor of S. sempervirens, but does not agree with his hypothesis that another ancestor is extinct and has not left close relatives. The original process of S, sempervirens may be shown as Fig. 1 .