Retroposon analysis and recent geological data suggest near-simultaneous divergence of the three superorders of mammals

Hidenori Nishihara, Shigenori Maruyama, Norihiro Okada

    Research output: Contribution to journalArticle

    119 Citations (Scopus)

    Abstract

    As a consequence of recent developments in molecular phylogenomics, all extant orders of placental mammals have been grouped into 3 lineages: Afrotheria, Xenarthra, and Boreotheria, which originated in Africa, South America, and Laurasia, respectively. Despite this advancement, the order of divergence of these 3 lineages remains unresolved. Here, we performed extensive retroposon analysis with mammalian genomic data. Surprisingly, we identified a similar number of informative retroposon loci that support each of 3 possible phylogenetic hypotheses: the basal position for Afrotheria (22 loci), Xenarthra (25 loci), and Boreotheria (21 loci). This result indicates that the divergence of the placental common ancestor into the 3 lineages occurred nearly simultaneously. Thus, we examined whether these molecular data could be integrated into the geological context by incorporating recent geological data. We obtained firm evidence that complete separation of Gondwana into Africa and South America occurred 120 ± 10 Ma. Accordingly, the previous reported time frame (division of Pangea into Gondwana and Laurasia at 148-138 Ma and division of Gondwana at 105 Ma) cannot be used to validate mammalian divergence order. Instead, we use our retroposon results and the recent geological data to propose that nearsimultaneous divisions of continents leading to isolated Africa, South America, and Laurasia caused nearly concomitant divergence of the ancient placental ancestor into 3 lineages, Afrotheria, Xenarthra, and Boreotheria, ≈120 Ma.

    Original languageEnglish
    Pages (from-to)5235-5240
    Number of pages6
    JournalProceedings of the National Academy of Sciences of the United States of America
    Volume106
    Issue number13
    DOIs
    Publication statusPublished - Mar 31 2009

    Keywords

    • Continental divisions
    • Incomplete lineage sorting
    • Long interspersed element 1
    • Mammalian phylogeny
    • Paleobiogeography

    ASJC Scopus subject areas

    • General

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