Blanchard Orland J
University of Florida Herbarium, Florida Museum of Natural History, 379 Dickinson Hall, P. O. Box 110575, Gainesville, Florida 32611-0575, U.S.A.
Comp Cytogenet. 2013 Apr 17;7(1):73-101. doi: 10.3897/CompCytogen.v7i1.4542. eCollection 2013.
Kosteletzkya C. Presl, 1835 (Malvaceae, Malvoideae, Hibisceae) includes 17 species, all but two of which are about evenly distributed between Africa and the northern Neotropics. Fifteen of the species were brought into cultivation and used in a hybridization program in an attempt to shed light on evolutionary and phytogeographic relationships in the genus. Chromosome pairing (x = 19) at meiosis was examined in 51 of the 56 interspecific hybrids that were produced, and the seven New World species, all diploids, were found to exhibit nearly complete pairing among themselves, indicating that they share a genome. By contrast the three African diploids showed low levels of chromosome pairing in crosses among themselves, leading to the recognition here of three distinct genomes, newly designated A, B and G. The African B-genome diploid, Kosteletzkya buettneri Gürke, 1889, was found to share its genome with the New World species. Four other African species are known to be tetraploids and a fifth, a hexaploid. The results of chromosome pairing in hybrids among all of the African species at all ploidy levels, plus the discovery of a spontaneously tetraploidized experimental intergenomic African diploid hybrid, suggest that three of the four tetraploids and the single hexaploid might all be allopolyploids built on the three known extant genomes. The fourth tetraploid paired poorly or moderately with these three genomes. Results are consistent with the hypothesis that Kosteletzkya arose in Africa, radiated at the diploid level, underwent natural interspecific hybridization, produced two tiers of allopolyploids, and at some more recent time dispersed a B-genome diploid to the New World where it underwent another radiation at the diploid level. Structural features of the fruits suggest adaptations for passive distribution by animals, potentially over long distances.
科斯特莱特茨基亚属（Kosteletzkya C. Presl，1835年）（锦葵科，锦葵亚科，木槿族）包含17个物种，其中除两个物种外，其余物种在非洲和新北界大致均匀分布。15个物种已被引入栽培，并用于杂交计划，以试图阐明该属的进化和植物地理关系。在产生的56个种间杂种中的51个中，对减数分裂时的染色体配对（x = 19）进行了检查，发现所有七个新世界物种均为二倍体，它们之间表现出几乎完全配对，表明它们共享一个基因组。相比之下，三个非洲二倍体在相互杂交时染色体配对水平较低，因此在此处识别出三个不同的基因组，新命名为A、B和G。发现非洲B基因组二倍体，即1889年的布氏科斯特莱特茨基亚（Kosteletzkya buettneri Gürke），与新世界物种共享其基因组。已知其他四个非洲物种为四倍体，还有一个为六倍体。所有非洲物种在所有倍性水平下的杂种中染色体配对的结果，加上发现了一个自发四倍体化的实验性基因组间非洲二倍体杂种，表明四个四倍体中的三个和单个六倍体可能都是基于三个已知现存基因组构建的异源多倍体。第四个四倍体与这三个基因组的配对较差或中等。结果与以下假设一致：科斯特莱特茨基亚属起源于非洲，在二倍体水平上辐射，经历自然种间杂交，产生了两层异源多倍体，并且在最近的某个时候将一个B基因组二倍体扩散到了新世界，在那里它在二倍体水平上经历了另一次辐射。果实的结构特征表明其适应于通过动物进行被动传播，可能是远距离传播。
