Department of Systematic and Evolutionary Botany, University of Vienna, Rennweg 14, 30 Vienna, Austria.
Ann Bot. 2011 Oct;108(5):895-906. doi: 10.1093/aob/mcr239. Epub 2011 Sep 2.
Sexually deceptive orchids of the genus Ophrys use mimicry of pollinator females to attract specific pollinators. Pollinator shifts may drive speciation in Ophrys, since novel pollinators may in principle act as isolating factors immediately. It is thus possible that evolution of novel species occurs rapidly and with a progenitor-derivative pattern. The aims of this study are to compare genetic structure and diversity among widespread and geographically restricted Ophrys taxa, to test whether genetic structure is associated with specific pollinators, and to investigate whether any widespread species may have acted as a progenitor for the evolution of more restricted taxa.
Genetic differentiation and diversity were investigated in O. leucadica and O. cinereophila, the two taxa of the Ophrys fusca sensu lato complex widespread in the Aegean, and three geographically restricted taxa from Rhodes, O. attaviria, O. parvula and O. persephonae, all differing in their specific pollinators. This was done using amplified fragment length polymorphism (AFLP) DNA fingerprinting, and sequencing of the low-copy nuclear gene LEAFY (LFY).
All taxa were found to be separate genetic entities, with O. leucadica forming two geographic groups from the west and east of the Aegean. Genetic structure was significantly shaped by pollinators and geography, and comparison of sequence and AFLP data revealed ancestral polymorphisms shared among several taxa. Among the sampled taxa, O. leucadica harbours the greatest genetic differentiation and geographic structure, and the highest genetic diversity. Part of the genome of O. parvula, endemic to Rhodes, may be derived from O. leucadica.
Pollinators probably influence the genetic structure of the investigated Ophrys species. The genetic pattern identified is consistent with O. leucadica being the oldest of the sampled taxa, making O. leucadica a candidate progenitor species from which more restricted taxa such as O. parvula may have evolved.
雄性兰花 Ophrys 属通过模仿雌性传粉者来吸引特定的传粉者。传粉者的转移可能会推动 Ophrys 的物种形成，因为新的传粉者原则上可以立即成为隔离因素。因此，新物种的进化可能非常迅速，并呈现出祖先进化模式。本研究的目的是比较广泛分布和地理上受限的 Ophrys 分类群之间的遗传结构和多样性，检验遗传结构是否与特定的传粉者有关，以及调查任何广泛分布的物种是否可能成为进化出更受限分类群的祖先进化体。
利用扩增片段长度多态性（AFLP）DNA 指纹图谱和低拷贝核基因 LEAFY（LFY）的测序，研究了 O. leucadica 和 O. cinereophila 这两个在爱琴海广泛分布的 Ophrys fusca 复合体的分类群，以及来自罗得岛的三个地理上受限的分类群，即 O. attaviria、O. parvula 和 O. persephonae，它们的特定传粉者不同。
所有分类群均被鉴定为独立的遗传实体，O. leucadica 由爱琴海东西两侧的两个地理群体组成。遗传结构明显受到传粉者和地理的影响，序列和 AFLP 数据的比较揭示了几个分类群之间共享的祖先多态性。在所采样的分类群中，O. leucadica 具有最大的遗传分化和地理结构，以及最高的遗传多样性。罗得岛特有分类群 O. parvula 的部分基因组可能源自 O. leucadica。
传粉者可能影响所研究的 Ophrys 物种的遗传结构。所确定的遗传模式与 O. leucadica 是采样分类群中最古老的物种一致，这使得 O. leucadica 成为一个候选祖先进化体，从该物种进化出了更为受限的分类群，如 O. parvula。
