Mismatch in the distribution of floral ecotypes and pollinators: insights into the evolution of sexually deceptive orchids

Plants are predicted to show floral adaptation to geographic variation in the most effective pollinator, potentially leading to reproductive isolation and genetic divergence. Many sexually deceptive orchids attract just a single pollinator species, limiting opportunities to experimentally investigate pollinator switching. Here we investigate Drakaea concolor, which attracts two pollinator species. Using pollinator choice tests, we detected two morphologically similar ecotypes within D. concolor. The common ecotype only attracted Zaspilothynnus gilesi, while the rare ecotype also attracted an undescribed species of Pogonothynnus. The rare ecotype occurred at populations nested within the distribution of the common ecotype, with no evidence of ecotypes occurring sympatrically. Surveying for pollinators at over 100 sites revealed that ecotype identity was not correlated with wasp availability, with most orchid populations only attracting the rare Z. gilesi. Using microsatellite markers, ge...有研究推测，植物会针对高效传粉媒介的地理差异演化出花部适应性特征，这可能进而引发生殖隔离与遗传分化。多数性欺骗型兰科植物（sexually deceptive orchids）仅能吸引单一传粉物种，这极大限制了通过实验探究传粉者转换的研究机会。本研究以同时吸引两种传粉媒介的异色锤兰（Drakaea concolor）为研究对象。通过传粉者选择实验（pollinator choice tests），我们在异色锤兰种群中发现了两个形态相似的生态型：常见生态型仅能吸引吉莱氏皱背土蜂（Zaspilothynnus gilesi），而稀有生态型则额外吸引一种尚未被描述的棒柄土蜂属（Pogonothynnus）物种。稀有生态型的种群分布嵌套于常见生态型的分布范围内，未发现两种生态型同域分布的证据。对100余个调查点的传粉媒介进行普查后发现，生态型的分布与胡蜂可获得性并无关联，多数兰科种群仅能吸引稀有的吉莱氏皱背土蜂（Zaspilothynnus gilesi）。利用微卫星标记（microsatellite markers）对……