Department of Biology, Lund University, SE-223 62 Lund, Sweden;
Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, CA 95060.
Proc Natl Acad Sci U S A. 2019 Mar 5;116(10):4406-4415. doi: 10.1073/pnas.1809007116. Epub 2019 Feb 14.
A major challenge in evolutionary biology is to understand how complex traits of multiple functions have diversified and codiversified across interacting lineages and geographic ranges. We evaluate intra- and interspecific variation in floral scent, which is a complex trait of documented importance for mutualistic and antagonistic interactions between plants, pollinators, and herbivores. We performed a large-scale, phylogenetically structured study of an entire plant genus (, Saxifragaceae), of which several species are coevolving with specialized pollinating floral parasites of the moth genus (Prodoxidae). We sampled 94 populations distributed across all 12 recognized species and subspecies, and four populations of related saxifragaceous species. Our results reveal an unusually high diversity of floral volatiles among populations, species, and clades within the genus. Moreover, we found unexpectedly major changes at each of these levels in the biosynthetic pathways used by local populations in their floral scents. Finally, we detected significant, but variable, genus- and species-level patterns of ecological convergence in the floral scent signal, including an impact of the presence and absence of two pollinating moth species. We propose that one potential key to understanding floral scent variation in this hypervariable genus is its geographically diverse interactions with the obligate specialized moths and, in some species and sites, more generalized copollinators.
进化生物学的一个主要挑战是理解具有多种功能的复杂特征如何在相互作用的谱系和地理范围内多样化和共同进化。我们评估了花卉香气的种内和种间变异，花卉香气是一种复杂特征，对植物、传粉者和草食动物之间的互利和拮抗相互作用具有重要意义。我们对整个石蒜科（Saxifragaceae）植物属进行了大规模的、系统发育结构的研究，其中一些物种与鳞翅目蛾属（Prodoxidae）的专门传粉寄生植物共同进化。我们采样了分布在 12 个已识别物种和亚种以及 4 个相关石蒜科物种的 94 个种群。我们的研究结果揭示了该属内种群、物种和进化枝之间花卉挥发物的异常高多样性。此外，我们还发现，在这些水平上，当地种群在其花卉香气中使用的生物合成途径都发生了出乎意料的重大变化。最后，我们检测到在花卉香气信号中存在显著但可变的属和种水平的生态趋同模式，包括两种传粉蛾物种的存在和缺失的影响。我们提出，理解这个高度可变属中花卉香气变异的一个潜在关键是其与专性专门化的鳞翅目昆虫在地理上的多样化相互作用，以及在一些物种和地点与更广泛的共同传粉者的相互作用。
