Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA 90095, USA.
Syst Biol. 2012 Oct;61(5):717-26. doi: 10.1093/sysbio/sys004. Epub 2012 Jan 9.
Although massively parallel sequencing has facilitated large-scale DNA sequencing, comparisons among distantly related species rely upon small portions of the genome that are easily aligned. Methods are needed to efficiently obtain comparable DNA fragments prior to massively parallel sequencing, particularly for biologists working with non-model organisms. We introduce a new class of molecular marker, anchored by ultraconserved genomic elements (UCEs), that universally enable target enrichment and sequencing of thousands of orthologous loci across species separated by hundreds of millions of years of evolution. Our analyses here focus on use of UCE markers in Amniota because UCEs and phylogenetic relationships are well-known in some amniotes. We perform an in silico experiment to demonstrate that sequence flanking 2030 UCEs contains information sufficient to enable unambiguous recovery of the established primate phylogeny. We extend this experiment by performing an in vitro enrichment of 2386 UCE-anchored loci from nine, non-model avian species. We then use alignments of 854 of these loci to unambiguously recover the established evolutionary relationships within and among three ancient bird lineages. Because many organismal lineages have UCEs, this type of genetic marker and the analytical framework we outline can be applied across the tree of life, potentially reshaping our understanding of phylogeny at many taxonomic levels.
尽管大规模平行测序促进了大规模的 DNA 测序,但对远距离相关物种的比较依赖于易于对齐的基因组的小部分。在大规模平行测序之前,需要有效地获得可比的 DNA 片段,特别是对于从事非模型生物的生物学家来说。我们引入了一类新的分子标记,由超保守基因组元件(UCEs)锚定,这些标记能够普遍实现数千个同源基因座的靶向富集和测序,这些基因座跨越了数亿年进化的物种。我们在这里的分析重点是在羊膜动物中使用 UCE 标记,因为在一些羊膜动物中,UCEs 和系统发育关系是众所周知的。我们进行了一个计算机实验,证明侧翼 2030 个 UCE 的序列包含足够的信息,能够明确恢复已建立的灵长类动物系统发育。我们通过对来自 9 种非模型鸟类的 2386 个 UCE 锚定基因座进行体外富集,扩展了这个实验。然后,我们使用其中 854 个位点的比对,明确恢复了三个古老鸟类谱系内部和之间已建立的进化关系。由于许多生物谱系都有 UCEs,这种遗传标记类型和我们概述的分析框架可以应用于生命之树的各个分支,有可能重塑我们对许多分类学水平的系统发育的理解。