Molecular dating and biogeography of the early placental mammal radiation
Molecular dating and biogeography of the early placental mammal radiation
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DOI：
10.1093/jhered/92.2.212
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发表时间：
2001-03-01
影响因子：
3.1
通讯作者：
O'Brien, SJ
中科院分区：
文献类型：
--
作者：
Eizirik, E;Murphy, WJ;O'Brien, SJ
基于对种18个基因片段(9779bp)的联合序列分析，确定了早期胎盘哺乳动物分化的时间和系统发育等级。利用源自不同理论方法的有根和无根的系统发育，获得了对真兽类四个主要支系的分歧的有力支持。胎盘哺乳动物系统发育中最早节点的最小分歧日期是用真丝虫树中9个不同节点的保守化石校准来估计的，该方法基于四元组的最大似然方法，该方法适应了谱系之间的速率差异。这些最小估计解决了和1.04亿年前之间最早的胎盘哺乳动物分叉节点，基本上每个案例都早于白垩纪-第三纪(K-T)界线。这些分歧的模式和时间允许对真空中历史上的主要分支事件进行地理解释，这些事件可能起源于南部超大陆冈瓦瓦兰，与其在9500-1.05亿年前分裂为非洲和南美洲的时间重合。我们提出了一个综合的基因组、古生物学和生物地理学假说来解释胎盘哺乳动物家族树上最早的分裂，并解决了目前化石和分子证据之间的差异。
The timing and phylogenetic hierarchy of early placental mammal divergences was determined based on combined DNA sequence analysis of 18 gene segments (9779 bp) from 64 species. Using rooted and unrooted phylogenies derived from distinct theoretical approaches, strong support for the divergence of four principal clades of eutherian mammals was achieved. Minimum divergence dates of the earliest nodes in the placental mammal phylogeny were estimated with a quartet-based maximum-likelihood method that accommodates rate variation among lineages using conservative fossil calibrations from nine different nodes in the eutherian tree. These minimum estimates resolve the earliest placental mammal divergence nodes at periods between 64 and 104 million years ago, in essentially every case predating the Cretaceous-Tertiary (K-T) boundary. The pattern and timing of these divergences allow a geographic interpretation of the primary branching events In eutherian history, likely originating in the southern supercontinent Gondwanaland coincident with its breakup into Africa and South America 95-105 million years ago. We propose an integrated genomic, paleontological, and biogeographic hypothesis to account for these earliest splits on the placental mammal family tree and address current discrepancies between fossil and molecular evidence.