PNAS：基因揭示鼠类的“非洲根”

佚名

    一种在1998年发现的岩鼠（rock  rat）已经成为一种“化石物种”，它是1100万年前灭绝的一个属的唯一幸存者。

    这种小啮齿动物有一张小鼠的脸庞和松鼠样的毛尾巴。这个物种是由生物学家在老挝于1998年发现。

    2005年，伦敦自然历史博物馆的研究人员揭示出这种啮齿动物是一种全新的哺乳动物属，并且是天竺鼠、非洲mole  rat和豪猪的亲戚。

    但是六个月后，其他研究人员反驳了这一推测，并指出老挝岩鼠不是新属，而是属于旧的的Diatomyidea——该属被认为在1100万年前已经灭绝。但是这项研究结论只是基于化石资料，因此产生争议。

    以色列Tel  Aviv大学的Dorothée  Huchon则利用7个基因研究老挝岩鼠的家谱，从而消除了有个这种鼠的血统争议。他的研究组比较了岩鼠和所有主要的现有鼠类中的这些基因，从而希望确定它在进化树中的位置。

    数据显示，这种鼠亲缘关系最近的是天竺鼠。Huchon表示，她的研究强有力地支持了“Laonastes（98年发现的这种岩鼠）是目前仅知的Diatomyidae鼠的幸存者”。这项研究的结果刊登在近期的《PNAS》杂志上。

原始出处:

Published online before print April 23, 2007
Proc. Natl. Acad. Sci. USA, 10.1073/pnas.0701289104

Evolution

Multiple molecular evidences for a living mammalian fossil

( Laonastes aenigmamus | molecular phylogeny | rodent | retroposons )

Dorothée Huchon ${dagger}$ ${ddagger}$ , Pascale Chevret ${sect}$ ¶, Ursula Jordan ||, C. William Kilpatrick ${dagger}$ ${dagger}$ , Vincent Ranwez ${sect}$ , Paulina D. Jenkins ${ddagger}$ ${ddagger}$ , Jürgen Brosius ||, and Jürgen Schmitz ${ddagger}$ ||

${dagger}$ Department of Zoology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel; ${sect}$ Department of Paleontology, Phylogeny, and Paleobiology, Institut des Sciences de l'Evolution, cc064, Université Montpellier II, Place E. Bataillon, 34095 Montpellier Cedex 5, France; ||Institute of Experimental Pathology, University of Münster, D-48149 Münster, Germany; ${dagger}$ ${dagger}$ Department of Biology, University of Vermont, Burlington, VT 05405-0086; and ${ddagger}$ ${ddagger}$ Department of Zoology, The Natural History Museum, London SW7 5BD, United Kingdom

Edited by Francisco J. Ayala, University of California, Irvine, CA, and approved March 18, 2007 (received for review February 11, 2007)

Laonastes aenigmamus is an enigmatic rodent first described in 2005. Molecular and morphological data suggested that it is the sole representative of a new mammalian family, the Laonastidae, and a member of the Hystricognathi. However, the validity of this family is controversial because fossil-based phylogenetic analyses suggest that Laonastes is a surviving member of the Diatomyidae, a family considered to have been extinct for 11 million years. According to these data, Laonastes and Diatomyidae are the sister clade of extant Ctenodactylidae (i.e., gundies) and do not belong to the Hystricognathi. To solve the phylogenetic position of Laonastes, we conducted a large-scale molecular phylogeny of rodents. The analysis includes representatives of all major rodent taxonomic groups and was based on 5.5 kb of sequence data from four nuclear and two mitochondrial genes. To further validate the obtained results, a short interspersed element insertion analysis including 11 informative loci was also performed. Our molecular data based on sequence and short interspersed element analyses unambiguously placed Laonastes as a sister clade of gundies. All alternative hypotheses were significantly rejected based on Shimodaira-Hasegawa tests, supporting the idea that Laonastes does not belong to the Hystricognathi. Molecular dating analysis also supports an ancient divergence, ${approx}$ 44 Mya ago, between Ctenodactylidae and Laonastes. These combined analyses support the hypothesis that Laonastes is indeed a living fossil. Protection of this surviving species would conserve an ancient mammalian family.