由牛津大学科学家组成的一个研究小组已经证明,13000年前活动在不列颠群岛以及欧洲和北美地区的大型猫科动物是狮子,而不是美洲虎或者虎。
该研究小组分析了从欧洲和美国采集的化石和残余物的DNA,确定了更新世(180万年前-1万年前)不列颠群岛生存的猫科动物家谱。该研究发表在本周的《分子生态学》(Molecular Ecology)上。
负责该项工作的牛津大学动物学系Ross Barnett博士表示,这些古代的狮子体型较大,比现在美洲的狮子大25%,有较长的腿更适合耐力跑。基因证明更新世的狮子与现代狮子关系密切。同时,石器时代留于山洞中的壁画表明它们当时已经形成群居,但雄性狮子还没有长出鬃毛。
该小组还发现,生存于更新世的狮子可以分为两支:一支定居在亚欧大陆北部以及阿拉斯加和加拿大育空地区,另一支来自北美洲南部。
这种异常分布与冰期有关。在冰期,西伯利亚和阿拉斯加之间形成了陆桥,狮子可以通过陆桥从亚欧大陆来到北美。后来,北美的冰盖阻隔了该迁移路线,从而产生了基因结构上完全不同的两种动物。
这些生活在不列颠群岛以及欧洲和北美地区的狮子的生存环境与目前非洲的大型猫科动物完全不同:在更新世,英国是苔原冻土地带,就像现在的俄罗斯草原一样,很多大型动物聚集那里,如哺乳动物、羊毛犀牛、巨型鹿等。13000年前,这些狮子和大型食草动物在大灭绝中消失。
该研究的合作者之一,牛津大学野生动物研究保护协会的Nobby Yamaguchi博士还表示,目前仍然不清楚大灭绝的原因,有研究表明可能与早期人类有关。同时,他认为该研究有助于描绘大灭绝之前大型动物的食性。对狮子的线粒体DNA分析表明,在大灭绝前3万-4万年,它们已经丧失了大量遗传多样性。可能原因是局部灭绝和种群重建,或者因为某些狮子群有优势而取代了其它群,但这一说法尚未被证实。(生物谷Bioon.com)
生物谷推荐原始出处:
Molecular Ecology Volume 18 Issue 8, Pages 1668 - 1677
Phylogeography of lions (Panthera leo ssp.) reveals three distinct taxa and a late Pleistocene reduction in genetic diversity
ROSS BARNETT*, BETH SHAPIRO?, IAN BARNES?, SIMON Y. W. HO§, JOACHIM BURGER?, NOBUYUKI YAMAGUCHI**, THOMAS F. G. HIGHAM??, H. TODD WHEELER??, WILFRIED ROSENDAHL§§, ANDREI V. SHER??,????, MARINA SOTNIKOVA***, TATIANA KUZNETSOVA???, GENNADY F. BARYSHNIKOV???, LARRY D. MARTIN§§§, C. RICHARD HARINGTON???, JAMES A. BURNS**** and ALAN COOPER????
*Department of Zoology, University of Oxford, Oxford OX1 3PS, UK, ?Department of Biology, Pennsylvania State University, University Park, PA 16801, USA, ?Department of Biology, University College London, London WC1E 6BT, UK, §Centre for Macroevolution and Macroecology, School of Botany and Zoology, Australian National University, Canberra, ACT 0200, Australia, ?Institute of Anthropology, Mainz University, 55099 Mainz, Germany, **Department of Biological and Environmental Sciences, University of Qatar, PO Box 2713, Doha, Qatar, ??Research Laboratory for Archaeology, University of Oxford, Oxford OX1 3QJ, UK, ??George C. Page Museum of La Brea Discoveries, Los Angeles, CA 90036, USA, §§Reiss-Engelhorn-Museen, D-68159 Mannheim, Germany, ??Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, 119071 Moscow, Russia, ***Geological Institute, Russian Academy of Sciences, 119017 Moscow, Russia, ???Palaeontological Department, Geological Faculty, Moscow State University, 119899 Moscow, Russia, ???Zoological Institute, Russian Academy of Sciences, 199034 St Petersburg, Russia, §§§Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS 66045, USA, ???Canadian Museum of Nature (Palaeobiology), Ottawa, ON, Canada K1P 6P4, ****Quaternary Palaeontology, Royal Alberta Museum, Edmonton, AB, Canada T5N 0M6, ????School of Earth and Environmental Sciences, University of Adelaide, Adelaide, SA 5005, Australia
Lions were the most widespread carnivores in the late Pleistocene, ranging from southern Africa to the southern USA, but little is known about the evolutionary relationships among these Pleistocene populations or the dynamics that led to their extinction. Using ancient DNA techniques, we obtained mitochondrial sequences from 52 individuals sampled across the present and former range of lions. Phylogenetic analysis revealed three distinct clusters: (i) modern lions, Panthera leo; (ii) extinct Pleistocene cave lions, which formed a homogeneous population extending from Europe across Beringia (Siberia, Alaska and western Canada); and (iii) extinct American lions, which formed a separate population south of the Pleistocene ice sheets. The American lion appears to have become genetically isolated around 340 000 years ago, despite the apparent lack of significant barriers to gene flow with Beringian populations through much of the late Pleistocene. We found potential evidence of a severe population bottleneck in the cave lion during the previous interstadial, sometime after 48 000 years, adding to evidence from bison, mammoths, horses and brown bears that megafaunal populations underwent major genetic alterations throughout the last interstadial, potentially presaging the processes involved in the subsequent end-Pleistocene mass extinctions.