Department of Biology, University of York, Heslington, York, UK.
Proc Biol Sci. 2010 May 22;277(1687):1597-606. doi: 10.1098/rspb.2009.2299. Epub 2010 Feb 3.
Comprising over half of all described species, the hexapods are central to understanding the evolution of global biodiversity. Direct fossil evidence suggests that new hexapod orders continued to originate from the Jurassic onwards, and diversity is presently higher than ever. Previous studies also suggest that several shifts in net diversification rate have occurred at higher taxonomic levels. However, their inferred timing is phylogeny dependent. We re-examine these issues using the supertree approach to provide, to our knowledge, the first composite estimates of hexapod order-level phylogeny. The Purvis matrix representation with parsimony method provides the most optimal supertree, but alternative methods are considered. Inferring ghost ranges shows richness of terminal lineages in the order-level phylogeny to peak just before the end-Permian extinction, rather than the present day, indicating that at least 11 more lineages survived this extinction than implied by fossils alone. The major upshift in diversification is associated with the origin of wings/wing folding and for the first time, to our knowledge, significant downshifts are shown associated with the origin of species-poor taxa (e.g. Neuropterida, Zoraptera). Polyneopteran phylogeny, especially the position of Zoraptera, remains important resolve because this influences findings regarding shifts in diversification. Our study shows how combining fossil with phylogenetic information can improve macroevolutionary inferences.
六足动物包含了所有已描述物种的一半以上,是理解全球生物多样性进化的核心。直接的化石证据表明,新的六足动物目从侏罗纪开始就不断起源,而且现在的多样性比以往任何时候都要高。先前的研究还表明,在较高的分类水平上,净多样化率发生了几次变化。然而,它们的推断时间依赖于系统发育。我们使用超级树方法重新研究这些问题,提供了据我们所知的第一个六足动物目级系统发育的综合估计。Purvis 矩阵表示与简约法提供了最优的超级树,但也考虑了其他方法。推断幽灵范围表明,在目级系统发育中,终端谱系的丰富度在二叠纪末灭绝之前达到峰值,而不是在今天,这表明至少有 11 个以上的谱系在这次灭绝中幸存下来,而不仅仅是化石所暗示的。多样化的主要上升与翅膀/翅膀折叠的起源有关,而且据我们所知,第一次显示出与物种贫乏的类群(如脉翅目、啮虫目)起源相关的显著下降。多足类的系统发育,特别是啮虫目的位置,仍然是一个重要的解决问题,因为这会影响关于多样化变化的发现。我们的研究表明,如何将化石与系统发育信息相结合可以改善宏观进化推断。