Department of Botany, University of Osnabrück, Barbarastrasse 11, Osnabrück, Germany.
Mol Ecol. 2012 Mar;21(5):1223-38. doi: 10.1111/j.1365-294X.2012.05460.x. Epub 2012 Jan 31.
To elucidate the evolutionary history of the genus Capsella, we included the hitherto poorly known species C. orientalis and C. thracica into our studies together with C. grandiflora, C. rubella and C. bursa-pastoris. We sequenced the ITS and four loci of noncoding cpDNA regions (trnL - F, rps16, trnH -psbA and trnQ -rps16). Sequence data were evaluated with parsimony and Bayesian analyses. Divergence time estimates were carried out with the software package BEAST. We also performed isozyme, cytological, morphological and biogeographic studies. Capsella orientalis (self-compatible, SC; 2n = 16) forms a clade (eastern lineage) with C. bursa-pastoris (SC; 2n = 32), which is a sister clade (western lineage) to C. grandiflora (self-incompatible, SI; 2n = 16) and C. rubella (SC; 2n = 16). Capsella bursa-pastoris is an autopolyploid species of multiple origin, whereas the Bulgarian endemic C. thracica (SC; 2n = 32) is allopolyploid and emerged from interspecific hybridization between C. bursa-pastoris and C. grandiflora. The common ancestor of the two lineages was diploid and SI, and its distribution ranged from eastern Europe to central Asia, predominantly confined to steppe-like habitats. Biogeographic dynamics during the Pleistocene caused geographic and genetic subdivisions within the common ancestor giving rise to the two extant lineages.
为了阐明甘蓝属的进化历史，我们将 hitherto 知之甚少的东方荠（Capsella orientalis）和 Thracic 荠（Capsella thracica）这两个物种与大花荠（Capsella grandiflora）、红果荠（Capsella rubella）和毛果荠（Capsella bursa-pastoris）一起纳入我们的研究。我们对 ITS 和四个非编码 cpDNA 区（trnL-F、rps16、trnH-psbA 和 trnQ-rps16）进行了测序。使用简约法和贝叶斯分析法对序列数据进行了评估。利用软件包 BEAST 进行了分歧时间估计。我们还进行了同工酶、细胞学、形态学和生物地理学研究。东方荠（自交亲和，SC；2n=16）与毛果荠（SC；2n=32）形成一个分支（东部谱系），而毛果荠是大花荠（自交不亲和，SI；2n=16）和红果荠（SC；2n=16）的姊妹分支（西部谱系）。毛果荠是一个多起源的同源多倍体物种，而保加利亚特有种 Thracic 荠（SC；2n=32）是异源多倍体，由毛果荠和大花荠之间的种间杂交产生。这两个谱系的共同祖先为二倍体和 SI，其分布范围从东欧到中亚，主要局限于草原状生境。更新世期间的生物地理动态导致共同祖先发生了地理和遗传分裂，从而产生了现存的两个谱系。
