一種在1998年發(fā)現(xiàn)的巖鼠（rock rat）已經(jīng)成為一種“化石物種”，它是1100萬年前滅絕的一個(gè)屬的唯一幸存者。
這種小嚙齒動(dòng)物有一張小鼠的臉龐和松鼠樣的毛尾巴,。這個(gè)物種是由生物學(xué)家在老撾于1998年發(fā)現(xiàn)。
2005年,，倫敦自然歷史博物館的研究人員揭示出這種嚙齒動(dòng)物是一種全新的哺乳動(dòng)物屬,，并且是天竺鼠、非洲mole rat和豪豬的親戚,。
但是六個(gè)月后,，其他研究人員反駁了這一推測(cè)，并指出老撾巖鼠不是新屬,，而是屬于舊的的Diatomyidea——該屬被認(rèn)為在1100萬年前已經(jīng)滅絕,。但是這項(xiàng)研究結(jié)論只是基于化石資料，因此產(chǎn)生爭(zhēng)議,。
以色列Tel Aviv大學(xué)的Dorothée Huchon則利用7個(gè)基因研究老撾巖鼠的家譜,，從而消除了有個(gè)這種鼠的血統(tǒng)爭(zhēng)議。他的研究組比較了巖鼠和所有主要的現(xiàn)有鼠類中的這些基因,，從而希望確定它在進(jìn)化樹中的位置,。
數(shù)據(jù)顯示，這種鼠親緣關(guān)系最近的是天竺鼠,。Huchon表示,，她的研究強(qiáng)有力地支持了“Laonastes（98年發(fā)現(xiàn)的這種巖鼠）是目前僅知的Diatomyidae鼠的幸存者”。這項(xiàng)研究的結(jié)果刊登在近期的《PNAS》雜志上,。
原始出處:
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 , Pascale Chevret ¶, Ursula Jordan ||, C. William Kilpatrick , Vincent Ranwez , Paulina D. Jenkins , Jürgen Brosius ||, and Jürgen Schmitz ||
Department of Zoology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel; 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; Department of Biology, University of Vermont, Burlington, VT 05405-0086; and 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, 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.
