Speciation and taxonomy of the endemic family Aucubaceae in Sino-Japanese floristic region

桃叶珊瑚属是桃叶珊瑚科唯一的一个属，是中国-日本区系的特有种，分布于中国西南部。该属中有10 ~ 20种雌雄异株的万年青灌木或乔木，但因其性状变异较大，分类上存在混乱。从染色体数目来看，认为A. japonica是该属中唯一的多倍体复合体。我们以前的研究表明，四倍体化在A.日本。中国的其他物种可能包括多倍体。本研究的目的是：（1）评价染色体的进化;（2）了解A.（3）对中国及邻近地区的几个种进行了基于叶绿体DNA非编码区和核DNA（ITS区和GapC基因外显子）序列的系统发育分析和流式细胞术分析，以修订该属的分类。结果表明：1）该属可分为暗紫色花灌木和淡黄色花高大种两个谱系; chinensis的报道有误; 3）有几个种是多倍体，其中大部分是多倍体，包括A. japonica，是异源多倍化起源

Aucuba, the only genus in the family Aucubaceae, is endemic to the Sino-Japanese floristic region, and is diversified around southwestern China. In the genus 10 to 20 dioecious evergreen shrub or tree species were recognized, but there are taxonomic confusions because of quite variable characters. For the chromosome numbers, it is thought that A. japonica was the only polyploid complex in the genus. Our previous study based on chloroplast phylogeny indicated that tetraploidization occurred independently at least three times within A. japonica. It is possible that other species in China might include polyploids. In the present study, (1) to evaluate the chromosomal evolution, (2) to understand the speciation process of A. japonica, (3) to revise the classification of the genus , we conducted the phylogenetic analysis based on additional sequences of chloroplast DNA noncoding regions and nuclear DNA (ITS region and exon of GapC gene) and the flow cytometric analysis for several species obtained from China and its neighboring regions. Our results indicate that 1) the genus is divided into two lineages of shrub having dark purple flowers and tall-species having pale yellow flowers, 2) the traditional recognition of A. chinensis has been misinterpreted, and 3) several species were polyploids and most of them, including A. japonica, were originated by allopolyploidizatios