Cataloging the very large number of   undescribed species of insects could be greatly accelerated by automated DNA   based approaches, but procedures for large-scale species discovery from   sequence data are currently lacking. Here, we use mitochondrial DNA variation   to delimit species in a poorly known beetle radiation in the genus Rivacindela from arid Australia. Among   468 individuals sampled from 65 sites and multiple morphologically   distinguishable types, sequence variation in three mtDNA genes (cytochrome   oxidase subunit 1, cytochrome b, 16S ribosomal RNA) was strongly partitioned   between 46 or 47 putative species identified with quantitative methods of   species recognition based on fixed unique (“diagnostic”) characters. The   boundaries between groups were also recognizable from a striking increase in   branching rate in clock-constrained calibrated trees. Models of stochastic   lineage growth (Yule models) were combined with coalescence theory to develop   a new likelihood method that determines the point of transition from species-level   (speciation and extinction) to population-level (coalescence) evolutionary   processes.

基于DNA的自动化方法，对大量未被描述的昆虫物种的分类有较大提升，但目前尚缺乏从序列数据中大规模发现物种的程序。在这里，我们使用线粒体DNA变异来界定虎甲属（Rivacindela）中一群鲜为人知的辐射进化而来的澳大利亚甲虫物种。从65个地点采集的468个标本和多个形态可区分模式标本中，扩增的3个线粒体基因（细胞色素氧化酶亚基1、细胞色素B、16S核糖体RNA）的序列变异强烈支持46个或47个的可能物种，通过稳定的鉴别特征定量方法鉴定相近的物种数。在受时钟约束的校准树中，分支率显著增加，也可以识别出组与组之间的界限。将随机谱系增长模型（Yule模型）与溯祖理论相结合，提出了一种新的似然方法，确定了从物种水平（物种形成和灭绝）到种群水平（溯祖）进化过程的转变点。