Data from: Biological factors contributing to bark and ambrosia beetle species diversification

The study of species diversification can identify the processes that shape patterns of species richness across the tree of life. Here we perform comparative analyses of species diversification using a large dataset of bark beetles. Three examined covariates – permanent inbreeding (sibling mating), fungus farming, and major host type – represent a range of factors that may be important for speciation. We studied the association of these covariates with species diversification while controlling for evolutionary lag on adaptation. All three covariates were significantly associated with diversification, but fungus farming showed conflicting patterns between different analyses. Genera that exhibited interspecific variation in host type had higher rates of species diversification, which may suggest that host switching is a driver of species diversification or that certain host types or forest compositions facilitate colonization and thus allopatric speciation. Because permanent inbreeding is thought to facilitate dispersal, the positive association of permanent inbreeding on diversification rates suggests that dispersal ability may contribute to species richness. Bark beetles are ecologically unique; however, our results indicate that their impressive species diversity is largely driven by mechanisms shown to be important for many organism groups.物种分化（species diversification）研究可揭示塑造生命之树各分支物种丰富度格局的演化过程。本研究依托大型小蠹虫（bark beetles）数据集开展物种分化的比较分析。我们选取3个协变量（covariates）——永久性近交（permanent inbreeding，同胞交配）、真菌养殖（fungus farming）与主要宿主类型（major host type）——作为可能对物种形成（speciation）具有重要作用的多类影响因子。在控制适应相关演化滞后（evolutionary lag on adaptation）效应的前提下，我们探究了上述协变量与物种分化的关联关系。三项协变量均与物种分化呈显著关联，但真菌养殖在不同分析中呈现出相悖的格局。宿主类型存在种间变异的属，其物种分化速率更高，这提示宿主转换或是物种分化的驱动因子，抑或是特定宿主类型或森林群落组成可促进定殖，进而推动异域物种形成（allopatric speciation）。鉴于永久性近交被认为有助于扩散（dispersal），永久性近交与分化速率间的正向关联表明，扩散能力或许对物种丰富度存在贡献。小蠹虫在生态学上具有独特性，但本研究结果显示，其惊人的物种多样性在很大程度上由已被证实对诸多生物类群均具有重要性的演化机制所驱动。