The complete mitochondrial genomes of two microbats, the horseshoe batRhinolophus pumilus, and the Japanese pipistrellePipistrellus abramus, and that of an insectivore, the long-clawed shrewSorex unguiculatus, were sequenced and analyzed phylogenetically by a maximum likelihood method in an effort to enhance our understanding of mammalian evolution. Our analysis suggested that (1) a sister relationship exists between moles and shrews, which form an eulipotyphlan clade; (2) chiropterans have a sister-relationship with eulipotyphlans; and (3) the Eulipotyphla/Chiroptera clade is closely related to fereuungulates (Cetartiodactyla, Perissodactyla and Carnivora). Divergence times on the mammalian tree were estimated from consideration of a relaxed molecular clock, the amino acid sequences of 12 concatenated mitochondrial proteins and multiple reference criteria. Moles and shrews were estimated to have diverged approximately 48 MyrBP, and bats and eulipotyphlans to have diverged 68 MyrBP. Recent phylogenetic controversy over the polyphyly of microbats, the monophyly of rodents, and the position of hedgehogs is also examined.

Authors and Affiliations

1. Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama, Japan, , , , , , JP

   Masato Nikaido, Kuniko Kawai & Norihiro Okada

2. Institute of Statistical Mathematics, Tokyo, Japan, , , , , , JP

   Yin Cao & Masami Hasegawa

3. Osaka City University Medical School, Osaka, Japan, , , , , , JP

   Masashi Harada

4. Gene Research Center, Tokyo Institute of Technology, Yokohama, Japan, , , , , , JP

   Satoru Tomita

Received: 21 December 2000 / Accepted: 16 February 2001

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