Genomic evidence reveals a radiation of placental mammals uninterrupted by the KPg boundary

作者：Liang Liu, Jin Zhang, Frank E. Rheindt, Fumin Lei, Yanhua Qu, Yu Wang, Yu Zhang, Corwin Sullivan, Wenhui Nie, Jinhuan Wang, Fengtang Yang, Jinping Chen, Scott V. Edwards, Jin Meng, Shaoyuan Wu · 发表于：Proceedings of the National Academy of Sciences · 年份：2017 · DOI：10.1073/pnas.1616744114 · 被引用次数：168 · 研究领域：Evolution and Paleontology Studies、Genomics and Phylogenetic Studies、Genetic diversity and population structure

The timing of the diversification of placental mammals relative to the Cretaceous-Paleogene (KPg) boundary mass extinction remains highly controversial. In particular, there have been seemingly irreconcilable differences in the dating of the early placental radiation not only between fossil-based and molecular datasets but also among molecular datasets. To help resolve this discrepancy, we performed genome-scale analyses using 4,388 loci from 90 taxa, including representatives of all extant placental orders and transcriptome data from flying lemurs (Dermoptera) and pangolins (Pholidota). Depending on the gene partitioning scheme, molecular clock model, and genic deviation from molecular clock assumptions, extensive sensitivity analyses recovered widely varying diversification scenarios for placental mammals from a given gene set, ranging from a deep Cretaceous origin and diversification to a scenario spanning the KPg boundary, suggesting that the use of suboptimal molecular clock markers and methodologies is a major cause of controversies regarding placental diversification timing. We demonstrate that reconciliation between molecular and paleontological estimates of placental divergence times can be achieved using the appropriate clock model and gene partitioning scheme while accounting for the degree to which individual genes violate molecular clock assumptions. A birth-death-shift analysis suggests that placental mammals underwent a continuous radiation across the KPg bound...