Coevolving communities-molecular phylogenetic analyses of myrmecophyte-insect symbioses in tropical rain forests

许多热带植物是蚂蚁的栖息地，因此可以保护蚂蚁免受食草动物的伤害。这些粘菌-蚂蚁系统大多包括介壳虫作为第三种伴生生物。介壳虫生活在植物中空的茎内，吸食植物的汁液，并为蚂蚁提供蜜露。我们研究了粘附性Macaranga植物、它们的栖息地火化蚁(Decacrema)和滋养球藻介壳昆虫之间的三向相互作用的进化。以前的研究表明，这三个属之间有紧密的联系，尽管有时还涉及其他几个属。全面采样的蚂蚁和鳞片的mtDNA COI系统发育图分别显示了10个和5个支持良好的谱系。对这两个系统发育和已发表的Macaranga系统发育的比较表明，没有共种。虽然蚂蚁规模和植物规模的相互作用是分散的，但蚂蚁-植物规模的相互作用是特定的，因为寄主转移受到植物茎性状的限制，这些性状本身与Macaranga系统发育相关。应用每My 1.5%的COI离散率，推测Macaranga的十足蚂蚁和球虫鳞片分别至少有12个和10个My Old，表明它们在东南亚湿润森林群落中自中新世以来一直在同时发生多样性。

Many tropical plants house ants and thereby gain protection from herbivores. Most of these myrmecophyte-ant systems include scale insects as the third associate. Scale insects live inside the plant hollow stem, suck the plant sap, and provide honeydew to the ants. We investigate the evolution of the three-way interaction among myrmecophytic Macaranga plants, their inhabitant Crematogaster (Decacrema) ants, and the trophobiont Coccus scale insects. Previous studies show that these three genera have a tight association although a few other genera are sometimes involved.The mtDNA COI phylogenies of comprehensively-sampled ants and scales reveal ten and five well-supported lineages, respectively. Comparisons of the two phylogenies and a published Macaranga phylogeny indicate an absence of cospeciation. Whereas the ant-scale and plant-scale interactions are diffuse, the ant-plant one is specific in the sense that host shifts have been constrained by plant stem traits that are themselves correlated with Macaranga phylogeny. Applying COI divergence rates of 1.5% per My, the Decacrema ants and the Coccus scales from Macaranga are inferred to be at least 12, and 10 My old, respectively, indicating that they have been diversifying contemporaneously since the mid-Miocene in the wet forest community of Southeast Asia.