Data from: c-Myc gene sequences and the phylogeny of bats and other eutherian mammals

The complete protein-coding sequences of the c-myc proto-oncogene were determined for five species of four new orders of eutherian (placental) mammals. These newly obtained sequences were aligned to each other and to other available orthologues for the phylogenetic estimation of eutherian interordinal relationships. Several measures of sequence difference and base composition were first calculated to assess the major evolutionary properties of the three codon positions and two protein-coding exons of the gene. On the basis of these calculations, different parsimony, distance, and maximum likelihood approaches were adopted, with the most sophisticated involving the separate, then combined, likelihood analyses of the third codon positions of exon 2 vs. all other sites. These phylogenetic approaches provide clear support for the grouping of Chiroptera (bats) with Artiodactyla (ruminants, camels, and pigs) and Carnivora (cats, dogs, and their allies), an interordinal arrangement that receives strong corroboration from other lines of evidence including complete mitochondrial DNA sequences. In contrast, these analyses fail to provide strong to reasonable support for any other interordinal group. This study concludes with specific recommendations about sampling and other strategies for maximizing the phylogenetic contributions of the c-myc gene to the continued resolution of the eutherian ordinal tree.

本研究针对真兽类（胎盘类）哺乳动物（eutherian (placental) mammals）四个新目下的五个物种，测定了其c-myc原癌基因（c-myc proto-oncogene）的完整蛋白编码序列。将这些新获得的序列进行两两比对，并与其他已公开的直系同源基因（orthologue）比对，以开展真兽类哺乳动物目间系统发育关系的推断。研究人员首先计算了多种序列差异及碱基组成指标，以评估该基因三个密码子位点与两个蛋白编码外显子（exon）的主要演化特征。基于上述计算结果，本研究采用了多种最大简约法、距离法及最大似然法，其中最精细的分析策略为先分别对第2外显子的第三个密码子位点与其余所有位点进行似然分析，再将二者合并分析。这些系统发育分析方法明确支持翼手目（Chiroptera，蝙蝠）与偶蹄目（Artiodactyla，反刍动物、骆驼及猪）、食肉目（Carnivora，猫、犬及其近缘类群）聚为一支，这一目间聚类关系得到了包括完整线粒体DNA（mitochondrial DNA）序列在内的多类独立证据的强力佐证。与之相反，本分析未对任何其他目间类群提供较强至合理的支持证据。本研究最后针对采样方案及其他研究策略提出了具体建议，以期最大化c-myc原癌基因在持续解析真兽类哺乳动物系统发育树过程中的贡献。