It is not known when the polyploid coast redwood (Sequoia sempervirens) evolved from its diploid ancestors, and what is its type of polyploidy. Whether close relatives of Sequoia, giant sequoia (Sequoiadendron giganteum) and dawn redwood (Metasequoia glyptostroboides), have possibly contributed to the ancestry of hexaploid of Sequoia remains an open question. The nature of hexaploidy in Sequoia has baffled biologists for more than a century. Based on the chromosome configurations in Sequoia, G. Ledyard Stebbins was the first geneticists who postulated in 1948 that Sequoia is an autoallohexaploid (AAAABB), and an ancient species of Metasequoia might have been one of the putative ancestors of Sequoia. After its chromosome number (2n=6x=66) was confirmed in hexaploid Sequoia, the type of polyploidy in Sequoia has been further investigated for the past 70 years by a number of investigators, using cytogenetic and genetic data. Although an autoallohexaploid (AAAABB) origin of Sequoia has remained one of the dominant hypotheses until recently, an alternative hypothesis, amongst other possible origins, was also put forth by Ahuja and Neale (2002), that Sequoia may be partially diploidized autohexaploid (AAAAAA), derived from some ancestral species of Sequoia, thus carrying a single ancestral genome. Cytogenetic, molecular genetics, and genome sequence data now support the hypothesis that Sequoia originated as an autohexaploid.

中文翻译：

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古地方性海岸红杉多倍体的起源和遗传性质（Sequoia sempervirens (D. Don) Endl.）

目前尚不清楚多倍体海岸红杉何时出现（红杉) 从它的二倍体祖先进化而来，它的多倍体类型是什么。是否为近亲红杉, 巨杉 (巨杉) 和黎明红木 (水杉), 可能对六倍体的祖先有贡献红杉仍然是一个悬而未决的问题。六倍体的性质红杉一个多世纪以来一直困扰着生物学家。基于染色体配置红杉, G. Ledyard Stebbins 是第一位在 1948 年假设的遗传学家红杉是自体异源六倍体 (AAAABB)，是一种古老的水杉可能是假定的祖先之一红杉. 在六倍体中确认其染色体数目（2n=6x=66）后红杉, 中的多倍体类型红杉在过去的 70 年里，许多研究人员使用细胞遗传学和遗传学数据对它进行了进一步研究。虽然自体异源六倍体 (AAAABB) 起源于红杉直到最近一直是主要假设之一，Ahuja 和 Neale (2002) 也提出了一个替代假设，以及其他可能的起源，即红杉可能是部分二倍体自六倍体 (AAAAAA)，源自某些祖先物种红杉，因此携带一个单一的祖先基因组。细胞遗传学、分子遗传学和基因组序列数据现在支持以下假设：红杉起源于同源六倍体。