Early Pleistocene (early + pleistocene)

Distribution by Scientific Domains
Distribution within Life Sciences


Selected Abstracts


Human evolution at the Matuyama-Brunhes boundary

EVOLUTIONARY ANTHROPOLOGY, Issue 1 2004
Article first published online: 12 FEB 200, Giorgio Manzi
Abstract The cranial morphology of fossil hominids between the end of the Early Pleistocene and the beginning of the Middle Pleistocene provides crucial evidence to understand the distribution in time and space of the genus Homo. This evidence is critical for evaluating the competing models regarding diversity within our genus. The debate focuses on two alternative hypotheses, one basically anagenetic and the other cladogenetic. The first suggests that morphological change is so diffused, slow, and steady that it is meaningless to apply species names to segments of a single lineage. The second is that the morphological variation observed in the fossil record can best be described as a number of distinct species that are not connected in a linear ancestor-descendant sequence. Today much more fossil evidence is available than was in the past to test these alternative hypotheses, as well as intermediate variants. Special attention must be paid to Africa because this is the most probable continental homeland for both the origin of the genus Homo (around 2.5,2 Ma),1 as well as the site, two million or so years later, of the emergence of the species H. sapiens.2 However, the African fossil record is very poorly represented between 1 Ma and 600 ka. Europe furnishes recent discoveries in this time range around the Matuyama-Brunhes chron boundary (780,000 years ago), a period for which, at present, we have no noteworthy fossil evidence in Africa or the Levant. Two penecontemporaneous sources of European fossil evidence, the Ceprano calvaria (Italy)3 and the TD6 fossil assemblage of Atapuerca (Spain)4 are thus of great interest for testing hypotheses about human evolution in the fundamental time span bracketed between the late Early and the Middle Pleistocene. This paper is based on a phenetic approach to cranial variation aimed at reviewing the Early-to-Middle Pleistocene trajectories of human evolution. The focus of the paper is on neither the origin nor the end of the story of the genus Homo, but rather its chronological and phylogenetic core. Elucidation of the evolutionary events that happened around 780 ka during the transition from the Early to Middle Pleistocene is one of the new frontiers for human paleontology, and is critical for understanding the processes that ultimately led to the origin of H. sapiens. [source]


Fossil fruits of Salsola L. s.l. and Halanthium K.Koch (Chenopodiaceae) from Lower Pleistocene lacustrine sediments in Armenia,

FEDDES REPERTORIUM, Issue 3-4 2008
Janna Akopian Dr.
For the first time imprints of fossil fruits of Salsola L. s.l. and Halanthium K.Koch (Chenopodiaceae, Salsoloideae,) are reported from the territory of Armenia, the latter being the first fossil record of the Southwest Asian genus worldwide. They were collected from fluvio-lacustrine diatomite layers of the Lower Pleistocene (Sisian series) in the upper-middle Vorotan river valley recently dated at 1.4,0.935 my (Early Pleistocene). The fossils are described, figured and compared with recent relatives. Due to poor preservation, the identity of the Salsola fruit cannot be specified but the similar genus Kochia can be excluded. The Halanthium fruit seems to differ from those of extant species. Both are also discussed in the context of the very poor fossil Salsoloideae record and of the actual and lower Pleistocene vegetation and environment. The findings of truly semidesert species underline the presence of open landscapes and extremely semiarid to arid conditions. However, stratigraphically more refined analyses are needed to draw conclusions about the former vegetation and the duration of arid periods because most macrofossils reported from the same strata indicate semiarid and even humid environments. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) Fossile Früchte von Salsola L. und Halanthium K.Koch (Chenopodiaceae) aus unterpleistozänen lakustrischen Sedimenten in Armenien Erstmals wird über Funde fossiler Früchte der Gattungen Salsola L. s.l. und Halanthium K.Koch (Chenopodiaceae, Salsoloideae) aus Armenien berichtet. Für die letztere Gattung handelt es sich weltweit um einen Erstfund. Die nur mäßig guten Abdrucke stammen aus fluvio-lakustrischen Diatomiten der Sisian Serie vom oberen Vorotan-Tal, die nach neuesten Datierungen 1,4,0,935 Millionen Jahre alt sind und damit in das Unterpleistozän gehören. Die Fossilien werden beschrieben, abgebildet und mit den nächsten rezenten Verwandten verglichen. Während bei der Salsola -Frucht wegen Beschädigungen vor der Einbettung keine Artbestimmung möglich ist, die Zugehörigkeit zu Kochia aber ausgeschlossen werden kann, stimmt die besser erhaltene Halanthium- Frucht mit keiner rezenten Art überein. Beide Arten werden im Zusammenhang mit dem bisher äußerst spärlichen Fossilbefund und im Hinblick auf ihren möglichen ökologischen und vegetationskundlichen Indikatorwert diskutiert. Die Nachweise dieser Halbwüstenpflanzen sprechen für eine waldfreie Umgebung und ein extremsemiarides oder arides Klima zur Zeit der Einbettung. Die gleichen Schichten enthalten aber vor allem Makrofossilien mesophytischer Gehölze, die an ein semiarides bis humides Klima gebunden sind. Weitergehende Rückschlüsse sind erst dann möglich, wenn eine feinstratigraphische Analyse vorliegt, durch die größere klimatische Fluktuationen nachgewiesen werden könnten. [source]


Tectonics and quaternary evolution of the Northern Apennines watershed area (upper course of Arno and Tiber rivers, Italy)

GEOLOGICAL JOURNAL, Issue 1 2009
Marco Bonini
Abstract This work examines the connection between Quaternary tectonics and erosion/incision processes in the primary Tuscan-Romagna watershed of the Northern Apennines, which essentially coincides with the topographic culmination of the Nero Unit structural ridge. Tectonic and geomorphic information were collected in the area where this ridge is crossed by the upper Tiber River course forming a deep gorge. Structural analysis and field mapping have revealed that the region experienced polyphase tectonics with superposed thrust folding events identifiable both at the map and mesoscopic scales. Hinterland-SSW-verging thrusts and thrust-related folds deformed the whole thrust pile during the latest deformation phase. Backthrusts/backfolds controlled the development of intermountain basins nearby the main watershed during the Early Pleistocene and seemingly deformed, in the Tiber gorge, a low-relief landscape developed in the Early Pleistocene (ca. 1.1,Ma). Successively, the upper Tiber River course area and Apennines axial zone underwent a generalized uplift, which is manifested by the deep incision of palaeo-morphologies. This proposed sequence of events correlates well with the major geodynamic change of the Apennines revealed by an acceleration of uplift rates in the Middle,Late Pleistocene. This latter event may also correlate with increased rates of river incision recorded in Europe as a consequence of uplift and/or climate change. Copyright © 2008 John Wiley & Sons, Ltd. [source]


The Pliocene to Early Pleistocene marine to fluviatile succession of the Seuil du Cotentin basins (Armorican Massif, Normandy, France)

JOURNAL OF QUATERNARY SCIENCE, Issue 3-4 2003
Olivier Dugué
Abstract Marine and fluvial Plio-Pleistocene deposits of the Seuil du Cotentin, western Normandy range in age from Late Pliocene to Early Pleistocene. They are preserved in small Cenozoic grabens and are divided into six new formations based on lithology, granulometry, sedimentary structures and associated fossils. The depositional environments of these formations change from marine to fluviatile and represent two transgression,regression cycles. This paper outlines the detailed stratigraphical relationships of the western Normandy Plio-Pleistocene succession and discusses its correlation with the adjacent eastern area in the Seine River valley (France), in Cornwall and in the southern North Sea basin (East Anglia, Belgium, The Netherlands). Copyright © 2003 John Wiley & Sons, Ltd. [source]


Taxonomic affinities and evolutionary history of the early Pleistocene hominids of Java: Dentognathic evidence

AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 4 2005
Yousuke Kaifu
Abstract Temporal changes, within-group variation, and phylogenetic positions of the Early Pleistocene Javanese hominids remain unclear. Recent debate focused on the age of the oldest Javanese hominids, but the argument so far includes little morphological basis for the fossils. To approach these questions, we analyzed a comprehensive dentognathic sample from Sangiran, which includes most of the existing hominid mandibles and teeth from the Early Pleistocene of Java. The sample was divided into chronologically younger and older groups. We examined morphological differences between these chronological groups, and investigated their affinities with other hominid groups from Africa and Eurasia. The results indicated that 1) there are remarkable morphological differences between the chronologically younger and older groups of Java, 2) the chronologically younger group is morphologically advanced, showing a similar degree of dentognathic reduction to that of Middle Pleistocene Chinese H. erectus, and 3) the chronologically older group exhibits some features that are equally primitive as or more primitive than early H. erectus of Africa. These findings suggest that the evolutionary history of early Javanese H. erectus was more dynamic than previously thought. Coupled with recent discoveries of the earliest form of H. erectus from Dmanisi, Georgia, the primitive aspects of the oldest Javanese hominid remains suggest that hominid groups prior to the grade of ca. 1.8,1.5 Ma African early H. erectus dispersed into eastern Eurasia during the earlier Early Pleistocene, although the age of the Javanese hominids themselves is yet to be resolved. Subsequent periods of the Early Pleistocene witnessed remarkable changes in the Javanese hominid record, which are ascribed either to significant in situ evolution or replacement of populations. Am J Phys Anthropol, 2005. © 2005 Wiley-Liss, Inc. [source]


Phylogeography of the Iberian populations of Mioscirtus wagneri (Orthoptera: Acrididae), a specialized grasshopper inhabiting highly fragmented hypersaline environments

BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 3 2009
JOAQUÍN ORTEGO
Phylogeographic studies from western Palaearctic have generally focused on species able to disperse and track their emerging suitable habitats after the last ice age. However, data on species whose biogeographical histories differ from this bulk of Palaearctic fauna are scarce. This is clearly the case of some specialized organisms inhabiting inland hypersaline environments, which are likely to have had a wider distribution range during the late Tertiary and may have persisted through the Pleistocene to the present day only constituting relict populations. In this study, we use partial sequences from two mitochondrial genes [16S rRNA (16S) and cytochrome oxidase subunit II (COII)] to investigate the phylogeography of the Iberian populations of Mioscirtus wagneri (Orthoptera: Acrididae), a specialized grasshopper exclusively inhabiting hypersaline low grounds. Our results show that M. wagneri exhibits a marked phylogeographical structure, forming three main clades which correspond with populations located in north-east, central,south-east and south-west Iberia. These geographical areas did not share any haplotype, indicating that gene flow between them is absent. Nested clade analyses revealed that these lineages have probably evolved in allopatry and data on sequence divergence suggest population fragmentation from the Early Pleistocene. Overall, these results provide a broader perspective on the contribution of historical climate/geological events to biogeographical patterns of organisms currently forming relict populations of great conservation concern. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 97, 623,633. [source]


Upwelling Process of the Western Himalaya Mountains: Height and Velocity Estimation Evidenced by Formation and Evolution of the Zanda Basin, Tibet, China

ACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 2 2010
Dagang ZHU
Abstract: Based on field geological survey, stratigraphic section measurement and indoor comprehensive investigation, the Zanda Basin's tectonic location in the Himalaya Plate was ascertained, and the formation and evolution of the Zanda Basin during the Pliocene to Early Pleistocene was classified as six stages: (a) primary rift-faulting stage, (b) quick rift-faulting Stage, (c) intensive rift-faulting stage, (d) stasis stage, (e) secondary rift-faulting stage, and (f) secondary quick rift-faulting stage. Based on this six-staged formation-evolution theory of the Zanda Basin, the upwelling process of the Western Himalaya Mountains from the Pliocene to Early Pleistocene was classified as the following five stages: (a) slow upwelling stage (5.4,4.4 Ma), (b) mid-velocity upwelling stage (4.4,3.5 Ma), (c) quick upwelling stage (3.5,3.2 Ma), (d) upwelling-ceasing stage (3.2,2.7 Ma), and (e) quick upwelling stage (2.7 Ma). Research has shown that in the duration from the Early Pliocene (4.7 Ma) to the End of Pliocene (2.67 Ma), which lasted 2.03 million years, the Himalaya Mountains had uplifted 1500 m at a velocity of 0.74 mm/a; this belongs to a mid-velocity upwelling. During the 1.31 million years in the Early Stage of the Early Pleistocene, the Himalaya Mountains had risen up another 1500 m at a velocity of 1.15 mm/a; this is a rather quick upwelling. All of these data have shown that the upwelling of the Western Himalaya Mountains is along a complicated process with multi-stages, multi-velocities, and non-uniformitarian features. [source]


Mesozoic-Cenozoic Tectonics of the Yellow Sea and Oil-Gas Exploration

ACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 1 2010
Tianfeng WAN
Abstract: The purpose of the present study was to study the tectonics of the Yellow Sea. Although oil-gas exploration has been undertaken for more than 30 years in the southern Yellow Sea, the exploration progress has achieved little. There are three tectonic periods with near N,S trending shortening and compression (260,200 Ma, 135,52 Ma and 23,0.78 Ma) and three tectonic periods with near E,W trending shortening and compression (200,135 Ma, 52,23 Ma and 0.78 Ma) at the Yellow Sea and adjacent areas during the Mesozoic and Cenozoic. The Indosinian tectonic period is the collision period between the Sino-Korean and Yangtze Plates, which formed the basic tectonic framework for the Yellow Sea area. There were strong intraplate deformations during the Yanshanian (200,135 Ma) and Sichuanian (135,52 Ma) periods with different tectonic models, which are also the main formation periods for endogenic metallic mineral deposits around the Yellow Sea. The three tectonic periods during the Cenozoic affect important influences for forming oil-gas reservoirs. The Eocene,Oligocene (52,23 Ma) is the main forming period for oil-gas sources. The Miocene,Early Pleistocene (23,0.78 Ma) was a period of favorable passage for oil-gas migration along NNE trending faults. Since the Middle Pleistocene (0.78 Ma) the NNE trending faults are closed and make good conditions for the reservation of oil-gas. The authors suggest that we pay more attention to the oil-gas exploration at the intersections between the NNE trending existing faults and Paleogene-Neogene systems in the southern Yellow Sea area. [source]


Tectonic Landform of Quaternary Lakes and Its Implications for Deformation in the Northern Qinghai-Tibet Plateau

ACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 1 2009
An WANG
Abstract: The Hohxil region in the northern Qinghai-Tibet Plateau is occupied by numerous plateau lakes, which have long been inferred as being tectonic products. However, so far little evidence has been found to support this tentative inference. Field survey and morphotectonic analysis of TM satellite images in the eastern segment of the Hohxil region revealed that Kusai Lake and Yelusu Lake are S-shaped pull-apart basins, which were dominated by left strike-slip master faults trending WNW-ESE. The pull-apart distances of the two lakes are analyzed to be <15,20 km and 15 km respectively. Based on studies of the faulting rate, the initiation ages of the pull-apart basins are suggested to be approximately in the Early Pleistocene. The pull-apart basin tectonics is further regarded as a common mechanism for the widely distributed large lake basins in the northern Qinghai-Tibet Plateau. Regional distribution of these pull-apart basins and their substantial intra-block slip suggest that a sinistral shear stress, which is independent of the distinguished strike-slip faults, has been imposed on across the northern Qinghai-Tibet Plateau. Thus, the intra-block slip may be an important expression of the eastward extrusion of the Plateau crustal material in accommodating the ongoing continent-continent convergence between India and Eurasia. The revelation of pull-apart tectonics within the Plateau hinterland provides field evidence and a possible style of deformation for the newly proposed continuous deformation by the global positioning system (GPS) measurement across the northern Qinghai-Tibet Plateau. A model, with respect to systematic tectonic landform development, for pull-apart basins is finally proposed. [source]


Sequence of the Cenozoic Mammalian Faunas of the Linxia Basin in Gansu, China

ACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 1 2004
DENG Tao
Abstract In the Linxia Basin on the northeast margin of the Tibetan Plateau, the Cenozoic strata are very thick and well exposed. Abundant mammalian fossils are discovered in the deposits from the Late Oligocene to the Early Pleistocene. The Dzungariotherium fauna comes from the sandstones of the Jiaozigou Formation, including many representative Late Oligocene taxa. The Platybelodon fauna comes from the sandstones of the Dongxiang Formation and the conglomerates of the Laogou Formation, and its fossils are typical Middle Miocene forms, such as Hemicyon, Amphicyon, Platybelodon, Choerolophodon, Anchitherium, and Hispanotherium. The Hipparion fauna comes from the red clay of the Liushu and Hewangjia Formations, and its fossils can be distinctly divided into four levels, including three Late Miocene levels and one Early Pliocene level. In the Linxia Basin, the Hipparion fauna has the richest mammalian fossils. The Equus fauna comes from the Wucheng Loess, and it is slightly older than that of the classical Early Pleistocene Nihewan Fauna. The mammalian faunas from the Linxia Basin provide the reliable evidence to divide the Cenozoic strata of this basin and correlate them with European mammalian sequence. [source]


The contribution of limb bone fracture patterns to reconstructing early hominid behaviour at Swartkrans cave (South Africa): archaeological application of a new analytical method

INTERNATIONAL JOURNAL OF OSTEOARCHAEOLOGY, Issue 4 2005
T. R. Pickering
Abstract Recently, Alcántara García et al. (in press) presented a new method and criteria for distinguishing between fractures imparted by hominid hammerstone percussion and carnivores chewing on ,green' limb bones of ungulates. The method uses a combination of fracture plane and fracture angle data that are useful for elucidating the relative role of hominids in the accumulation of prehistoric archaeofaunas, especially when employed in concert with other classes of taphonomic data. We briefly summarise the method and apply it to the ungulate limb bone subassemblage from Swartkrans Member 3, a c. 1.0 million year old site from South Africa that preserves Early Stone Age lithic artefacts, hominid fossils, and an abundant mammalian fauna with cutmarked, hammerstone-percussed and burned bone specimens. Results of the fracture pattern analysis corroborate indications from other lines of taphonomic data that there was minimal carnivore,hominid interdependence in the formation of the fauna, and that carnivores were probably responsible for the majority of the bone collection in Member 3. However, we also document a significant hominid influence on assemblage formation, a finding that expands and refines our understanding of large animal carcass foraging by hominids in southern Africa during the early Pleistocene. Copyright © 2004 John Wiley & Sons, Ltd. [source]


Differentiation of golden-ringed dragonfly Anotogaster sieboldii (Selys, 1854) (Cordulegastridae: Odonata) in the insular East Asia revealed by the mitochondrial gene genealogy with taxonomic implications

JOURNAL OF ZOOLOGICAL SYSTEMATICS AND EVOLUTIONARY RESEARCH, Issue 2 2008
T. Kiyoshi
Abstract Molecular phylogeographical analyses of Anotogaster sieboldii (Selys, 1854) were conducted to reveal the differentiation process of insular populations. The gene genealogy based on 845 bp of the mitochondrial genes (cytochrome oxidase subunit I and subunit II) indicated that A. sieboldii includes two deeply separated lineages. These two major lineages seem to have differentiated in Miocene before the formation of the insular East Asia. One lineage includes three inner clades that correspond to the populations of northern area (the Japanese main islands, Korean Peninsula, Yakushima), Amamioshima and Okinawajima. Populations of Central Ryukyu, including Amamioshima and Okinawajima, might have been divided from the northern populations in early Pleistocene. The other major lineage includes populations of the Yaeyama Group, Taiwan and East China. The former two populations were reconstructed as a reciprocal monophyletic group. Populations of Taiwan and Yaeyama Groups would have been separated from the continental ones in Pleistocene. These two highly divergent lineages should be recognized as distinct species. Furthermore, the mitochondrial lineages revealed six genetically distinct and geographically isolated assemblages: (1) northern populations, (2) Amamioshima, (3) Okinawajima, (4) Yaeyama Group, (5) Taiwan and (6) East China. Zusammenfassung An der Libelle Anotogaster sieboldii wurden molekulare phylogeographische Analysen durchgeführt, um ihre Differenzierungen in Insel-Populationen zu erkennen. Die Gen-Genealogie (basierend auf 845 bp mitochondrialer Gene (COI und COII) zeigte, dass A. sieboldii zwei weit getrennte Abstammungslinien enthält, die sich wahrscheinlich im Miozän vor der Bildung der ostasiatischen Inselwelt differenzierten. Eine Abstammungslinie schließt drei Gruppierungen ein, die den Populationen in den nördlichen Gebieten entsprechen: die japanischen Hauptinseln, die koreanische Halbinsel Yakushima, Amamioshima sowie Okinawajima. Die Populationen von Zentral-Ryukyu, einschließlich Amamioshima und Okinawajima, ist möglicherweise im frühen Pleistozän von den nördlichen Populationen getrennt worden. Die andere größere Abstammungslinie schließt die Populationen der Yaeyama-Gruppe, Taiwan und das Östliche China ein. Zwei dieser Populationen wurden als Teil einer entsprechenden monophyletischen Gruppe rekonstruiert; die Populationen von Taiwan und die Yaeyama-Gruppe sind danach im Pleistozän von den kontinentalen Populationen getrennt worden. Diese zwei sehr differierenden Abstammungslinien sollten als verschiedene Spezies betrachtet werden. Weiterhin werden sechs genetisch verschiedene und geographisch isolierte Gruppierungen deutlich: (1) die nördlichen Populationen, (2) Amamioshima, (3) Okinawajima, (4) die Yaeyama-Gruppe, (5) Taiwan und (6) die Population im östlichen China. [source]


Phylogeography of the marine macroalga Sargassum hemiphyllum (Phaeophyceae, Heterokontophyta) in northwestern Pacific

MOLECULAR ECOLOGY, Issue 14 2010
CHI CHIU CHEANG
Abstract Sargassum hemiphyllum is commonly found in Japan and Korea, with a variety, var. chinense, that is found distributed in the southern Chinese coast. We previously reported distinct genetic differentiation between the two taxa based on the PCR-RFLP data of plastid RubiscoL-S spacer. The present study aims at elucidating the phylogeographic pattern of S. hemiphyllum based on more markers in the nuclear and extranuclear genomes, with a view to reveal the occurrence of hybridization. The two allopatrically distributed taxa were found to be genetically distinct in nuclear ITS2, plastidial Rubisco (Rbc) and mitochondrial TrnW_I (Trn) spacers. Their divergence was postulated to be attributable to the vicariant event which resulted from the isolation of the Sea of Japan during the late Miocene (6.58,11.25 Mya). Divergence within both S. hemiphyllum and the chinense variety was observed based on Trn spacer, while the divergence in S. hemiphyllum was further confirmed in Rbc spacer. This divergence appears to correspond to the separation of the Japanese populations between the Sea of Japan and the Pacific that occurred around 0.92,2.88 Mya (the early Pleistocene). The presence of an ITS2 clone resembling var. chinense sequences in a Japanese population of S. hemiphyllum (JpNS) raises the possibility of the introgression of var. chinense individuals into S. hemiphyllum population. Compared to that between S. hemiphyllum and the chinense variety, hybridization among the Japanese and Korean populations of S. hemiphyllum is highly probable as all these individuals share a pool of nuclear ITS2 sequences, possibly attributable to incomplete concerted evolution of ITS2. [source]


A NEW SPECIES OF DICERORHINUS (RHINOCEROTIDAE) FROM THE PLIO-PLEISTOCENE OF MYANMAR

PALAEONTOLOGY, Issue 6 2008
ZIN-MAUNG-MAUNG-THEIN
Abstract:, A skull and mandible of the new species Dicerorhinus gwebinensis sp. nov. of Rhinocerotidae (Mammalia, Perissodactyla) is described. The material is collected from the upper part of the Irrawaddy sediments (Plio-Pleistocene) in central Myanmar. D. gwebinensis sp. nov. is morphologically more similar to the extant species D. sumatrensis (Sumatran rhinoceros) than to other species of the genus but differs from D. sumatrensis in having the comparatively shorter nasal, the more concave dorsal profile of the skull, the more elevated occiput and presence of molar crista in M3/. This is the first discovery of Dicerorhinus in the upper Miocene to lower Pleistocene of the Indian subcontinent and Mainland Southeast Asia, and fills the chronological and geographical gap of this lineage in Asia. The Dicerorhinus clade probably migrated into Southeast Asia from East Asia by the Pliocene or early Pleistocene. This hypothesis is supported by the scarcity or absence of this clade in the Neogene mammalian fauna of the Indian Subcontinent. [source]


Chloroplast DNA Variation and Biogeography in the Genus Rorippa Scop. (Brassicaceae)

PLANT BIOLOGY, Issue 1 2002
W. Bleeker
Abstract: Phylogenetic relationships and biogeography of 25 Rorippa species were studied using sequences of two non-coding regions of chloroplast DNA (trnL intron, trnL/F spacer). Our results indicate a close relationship between European (R. islandica ssp. islandica, R. pyrenaica) and North American (R. curvipes, R. sinuata) mountain species. The polyploid European lowland species R. amphibia, R. palustris and R. sylvestris are much younger than the mountain species and have their closest relatives in western Asia and Siberia. Different colonization routes of the southern hemisphere are discussed for Rorippa. Australasia was colonized at least twice, most likely via the Malayan route. A molecular clock approach dates the first colonization to the end of Pliocene or early Pleistocene. R. gigantea reached Australia later in the Pleistocene. Our data provide evidence for an amphitropical disjunction between the South American (R. philippiana) and North American (R. curvisiliqua) species. Long-distance dispersal via migrating birds is the most likely explanation for this intercontinental disjunction. Two of the analysed African species (R. nudiuscula, R. madagascariensis) have their closest relative (R. austriaca) in eastern Europe and western Asia. The lack of sequence divergence among these species indicates a colonization event probably not earlier than 100 000 years ago. [source]


Relative limb strength and locomotion in Homo habilis

AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 1 2009
Christopher Ruff
Abstract The Homo habilis OH 62 partial skeleton has played an important, although controversial role in interpretations of early Homo locomotor behavior. Past interpretive problems stemmed from uncertain bone length estimates and comparisons using external bone breadth proportions, which do not clearly distinguish between modern humans and apes. Here, true cross-sectional bone strength measurements of the OH 62 femur and humerus are compared with those of modern humans and chimpanzees, as well as two early H. erectus specimens,KNM-WT 15000 and KNM-ER 1808. The comparative sections include two locations in the femur and two in the humerus in order to encompass the range of possible section positions in the OH 62 specimens. For each combination of section locations, femoral to humeral strength proportions of OH 62 fall below the 95% confidence interval of modern humans, and for most comparisons, within the 95% confidence interval of chimpanzees. In contrast, the two H. erectus specimens both fall within or even above the modern human distributions. This indicates that load distribution between the limbs, and by implication, locomotor behavior, was significantly different in H. habilis from that of H. erectus and modern humans. When considered with other postcranial evidence, the most likely interpretation is that H. habilis, although bipedal when terrestrial, still engaged in frequent arboreal behavior, while H. erectus was a completely committed terrestrial biped. This adds to the evidence that H. habilis (sensu stricto) and H. erectus represent ecologically distinct, parallel lineages during the early Pleistocene. Am J Phys Anthropol, 2009. © 2008 Wiley-Liss, Inc. [source]


Monophyletic origin of domestic bactrian camel (Camelus bactrianus) and its evolutionary relationship with the extant wild camel (Camelus bactrianus ferus)

ANIMAL GENETICS, Issue 4 2009
R. Ji
Summary The evolutionary relationship between the domestic bactrian camel and the extant wild two-humped camel and the factual origin of the domestic bactrian camel remain elusive. We determined the sequence of mitochondrial cytb gene from 21 camel samples, including 18 domestic camels (three Camelus bactrianus xinjiang, three Camelus bactrianus sunite, three Camelus bactrianus alashan, three Camelus bactrianus red, three Camelus bactrianus brown and three Camelus bactrianus normal) and three wild camels (Camelus bactrianus ferus). Our phylogenetic analyses revealed that the extant wild two-humped camel may not share a common ancestor with the domestic bactrian camel and they are not the same subspecies at least in their maternal origins. Molecular clock analysis based on complete mitochondrial genome sequences indicated that the sub-speciation of the two lineages had begun in the early Pleistocene, about 0.7 million years ago. According to the archaeological dating of the earliest known two-humped camel domestication (5000,6000 years ago), we could conclude that the extant wild camel is a separate lineage but not the direct progenitor of the domestic bactrian camel. Further phylogenetic analysis suggested that the bactrian camel appeared monophyletic in evolutionary origin and that the domestic bactrian camel could originate from a single wild population. The data presented here show how conservation strategies should be implemented to protect the critically endangered wild camel, as it is the last extant form of the wild tribe Camelina. [source]