Rapid diversification rates in Amazonian Chrysobalanaceae inferred from plastid genome phylogenetics

We studied the evolutionary history of Chrysobalanaceae with phylogenetic analyses of complete plastid genomes from 156 species to assess the tempo of diversification in the Neotropics and help to unravel the causes of Amazonian plant diversification. These plastid genomes had a mean length of 162,204 base pairs, and the nearly complete DNA sequence matrix, with reliable fossils, was used to estimate a phylogenetic tree. Chrysobalanaceae diversified from 38.9 Mya (95% highest posterior density, 95%HPD: 34.2-43.9 Mya). A single clade containing almost all Neotropical species arose after a single dispersal event from the Palaeotropics into the Amazonian biome c. 29.1 Mya (95%HPD: 25.5-32.6 Mya), with subsequent dispersals into other Neotropical biomes. All Neotropical genera diversified from 10 to 14 Mya, lending clear support to the role of Andean orogeny as a major cause of diversification in Chrysobalanaceae. In particular, the understory genus Hirtella diversified extremely rapidly, p...

本研究针对156个物种的完整质体基因组（plastid genome）开展系统发育分析，以此探究可可李科（Chrysobalanaceae）的演化历史，评估新热带区（Neotropics）的类群分化速率，并为阐明亚马逊植物类群分化的成因提供支撑。本次研究所用的质体基因组平均长度为162204个碱基对，结合可靠化石记录构建的近乎完整DNA序列矩阵被用于估算系统发育树。可可李科的类群分化起始于38.9百万年前（million years ago, Mya，95%最高后验密度（highest posterior density，95%HPD）：34.2~43.9 Mya）。一个包含几乎所有新热带区物种的单系分支，源自古热带区（Palaeotropics）向亚马逊生物群系（Amazonian biome）的单次扩散事件，发生于约29.1 Mya（95%HPD：25.5~32.6 Mya），后续该分支进一步扩散至其他新热带生物群系。所有新热带区的植物属均在10至14 Mya期间发生分化，这为安第斯造山运动（Andean orogeny）作为可可李科类群分化的核心驱动因素提供了明确佐证。尤为特别的是，林下层植物属Hirtella的类群分化速率极快，p...