Institute of Experimental Pathology (ZMBE), University of Münster, Von-Esmarch-Str. 56, Münster, Germany.
Gene. 2010 May 1;455(1-2):22-31. doi: 10.1016/j.gene.2010.02.002. Epub 2010 Feb 11.
The native rodents are the most species-rich placental mammal group on the Australian continent. Fossils of native Australian rodents belonging to the group Conilurini are known from Northern Australia at 4.5Ma. These fossil assemblages already display a rich diversity of rodents, but the exact timing of their arrival on the Australian continent is not yet established. The complete mitochondrial genomes of two native Australian rodents, Leggadina lakedownensis (Lakeland Downs mouse) and Pseudomys chapmani (Western Pebble-mound mouse) were sequenced for investigating their evolutionary history. The molecular data were used for studying the phylogenetic position and divergence times of the Australian rodents, using 12 calibration points and various methods. Phylogenetic analyses place the native Australian rodents as the sister-group to the genus Mus. The Mus-Conilurini calibration point (7.3-11.0Ma) is highly critical for estimating rodent divergence times, while the influence of the different algorithms on estimating divergence times is negligible. The influence of the data type was investigated, indicating that amino acid data are more likely to reflect the correct divergence times than nucleotide sequences. The study on the problems related to estimating divergence times in fast-evolving lineages such as rodents, emphasize the choice of data and calibration points as being critical. Furthermore, it is essential to include accurate calibration points for fast-evolving groups, because the divergence times can otherwise be estimated to be significantly older. The divergence times of the Australian rodents are highly congruent and are estimated to 6.5-7.2Ma, a date that is compatible with their fossil record.
澳大利亚本土啮齿动物是澳大利亚大陆胎盘哺乳动物中物种最丰富的群体。450 万年前，在澳大利亚北部发现了属于 Conilurini 组的澳大利亚本土啮齿动物化石。这些化石组合已经显示出丰富的啮齿动物多样性，但它们到达澳大利亚大陆的确切时间尚不清楚。为了研究它们的进化历史，对两种澳大利亚本土啮齿动物（Leggadina lakedownensis（拉克兰唐斯鼠）和 Pseudomys chapmani（西部卵石丘鼠））的完整线粒体基因组进行了测序。使用 12 个校准点和各种方法，利用分子数据研究了澳大利亚啮齿动物的系统发育位置和分化时间。系统发育分析将澳大利亚本土啮齿动物置于 Mus 属的姊妹群中。Mus-Conilurini 校准点（7.3-11.0Ma）对于估计啮齿动物的分化时间非常关键，而不同算法对估计分化时间的影响可以忽略不计。还研究了数据类型的影响，表明与核苷酸序列相比，氨基酸数据更有可能反映正确的分化时间。对快速进化谱系（如啮齿动物）中估计分化时间相关问题的研究强调了数据和校准点选择的重要性。此外，对于快速进化的群体，必须包含准确的校准点，否则分化时间可能会被估计为明显更老。澳大利亚啮齿动物的分化时间高度一致，估计为 6.5-7.2Ma，与它们的化石记录相符。
