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.

物种多样化研究可揭示塑造生命之树（tree of life）各分支物种丰富度格局的核心演化过程。本研究依托大型树皮甲虫（bark beetles）数据集开展物种多样化比较分析。本次研究考察的三项协变量（covariate）——永久性近交（同胞交配，permanent inbreeding (sibling mating)）、真菌养殖（fungus farming）以及主要宿主类型（major host type）——涵盖了可能对物种形成（speciation）至关重要的多类影响因子。本研究在控制适应过程中进化滞后效应的前提下，分析了上述协变量与物种多样化之间的关联。三项协变量均与物种多样化呈显著关联，但真菌养殖在不同分析中呈现出相悖的结果模式。宿主类型存在种间变异的属，其物种多样化速率更高，这提示宿主转换可能是物种多样化的驱动因子，抑或是特定宿主类型或森林群落结构可促进定殖过程，进而推动异地物种形成（allopatric speciation）。由于永久性近交被认为可促进扩散能力，永久性近交与多样化速率之间的正相关关联表明，扩散能力或许是物种丰富度提升的重要贡献因素。尽管树皮甲虫在生态学上具有独特性，但本研究结果显示，其丰富的物种多样性主要由在众多生物类群中均被证实具有重要作用的演化机制所驱动。