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  • 1
    Publication Date: 2015-06-21
    Description: The oft-repeated claim that Earth’s biota is entering a sixth "mass extinction" depends on clearly demonstrating that current extinction rates are far above the "background" rates prevailing in the five previous mass extinctions. Earlier estimates of extinction rates have been criticized for using assumptions that might overestimate the severity of the extinction crisis. We assess, using extremely conservative assumptions, whether human activities are causing a mass extinction. First, we use a recent estimate of a background rate of 2 mammal extinctions per 10,000 species per 100 years (that is, 2 E/MSY), which is twice as high as widely used previous estimates. We then compare this rate with the current rate of mammal and vertebrate extinctions. The latter is conservatively low because listing a species as extinct requires meeting stringent criteria. Even under our assumptions, which would tend to minimize evidence of an incipient mass extinction, the average rate of vertebrate species loss over the last century is up to 114 times higher than the background rate. Under the 2 E/MSY background rate, the number of species that have gone extinct in the last century would have taken, depending on the vertebrate taxon, between 800 and 10,000 years to disappear. These estimates reveal an exceptionally rapid loss of biodiversity over the last few centuries, indicating that a sixth mass extinction is already under way. Averting a dramatic decay of biodiversity and the subsequent loss of ecosystem services is still possible through intensified conservation efforts, but that window of opportunity is rapidly closing.
    Electronic ISSN: 2375-2548
    Topics: Natural Sciences in General
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  • 2
    Publication Date: 2011-08-13
    Description: Plants and their arbuscular mycorrhizal fungal symbionts interact in complex underground networks involving multiple partners. This increases the potential for exploitation and defection by individuals, raising the question of how partners maintain a fair, two-way transfer of resources. We manipulated cooperation in plants and fungal partners to show that plants can detect, discriminate, and reward the best fungal partners with more carbohydrates. In turn, their fungal partners enforce cooperation by increasing nutrient transfer only to those roots providing more carbohydrates. On the basis of these observations we conclude that, unlike many other mutualisms, the symbiont cannot be "enslaved." Rather, the mutualism is evolutionarily stable because control is bidirectional, and partners offering the best rate of exchange are rewarded.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kiers, E Toby -- Duhamel, Marie -- Beesetty, Yugandhar -- Mensah, Jerry A -- Franken, Oscar -- Verbruggen, Erik -- Fellbaum, Carl R -- Kowalchuk, George A -- Hart, Miranda M -- Bago, Alberto -- Palmer, Todd M -- West, Stuart A -- Vandenkoornhuyse, Philippe -- Jansa, Jan -- Bucking, Heike -- New York, N.Y. -- Science. 2011 Aug 12;333(6044):880-2. doi: 10.1126/science.1208473.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institute of Ecological Science, Vrije Universiteit, 1081 HV Amsterdam, Netherlands. toby.kiers@vu.nl〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21836016" target="_blank"〉PubMed〈/a〉
    Keywords: Biological Evolution ; Carbohydrate Metabolism ; Carbon/metabolism ; Glomeromycota/genetics/growth & development/*physiology ; Medicago truncatula/*microbiology/*physiology ; Molecular Sequence Data ; Mycorrhizae/genetics/growth & development/*physiology ; Phosphorus/metabolism ; Plant Roots/*microbiology/physiology ; RNA, Fungal/metabolism ; Species Specificity ; *Symbiosis
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 3
    Publication Date: 2012-09-29
    Description: Evolutionary modification has produced a spectrum of animal defence traits to escape predation, including the ability to autotomize body parts to elude capture. After autotomy, the missing part is either replaced through regeneration (for example, in urodeles, lizards, arthropods and crustaceans) or permanently lost (such as in mammals). Although most autotomy involves the loss of appendages (legs, chelipeds, antennae or tails, for example), skin autotomy can occur in certain taxa of scincid and gekkonid lizards. Here we report the first demonstration of skin autotomy in Mammalia (African spiny mice, Acomys). Mechanical testing showed a propensity for skin to tear under very low tension and the absence of a fracture plane. After skin loss, rapid wound contraction was followed by hair follicle regeneration in dorsal skin wounds. Notably, we found that regenerative capacity in Acomys was extended to ear holes, where the mice exhibited complete regeneration of hair follicles, sebaceous glands, dermis and cartilage. Salamanders capable of limb regeneration form a blastema (a mass of lineage-restricted progenitor cells) after limb loss, and our findings suggest that ear tissue regeneration in Acomys may proceed through the assembly of a similar structure. This study underscores the importance of investigating regenerative phenomena outside of conventional model organisms, and suggests that mammals may retain a higher capacity for regeneration than was previously believed. As re-emergent interest in regenerative medicine seeks to isolate molecular pathways controlling tissue regeneration in mammals, Acomys may prove useful in identifying mechanisms to promote regeneration in lieu of fibrosis and scarring.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3480082/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3480082/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Seifert, Ashley W -- Kiama, Stephen G -- Seifert, Megan G -- Goheen, Jacob R -- Palmer, Todd M -- Maden, Malcolm -- T32 DK074367/DK/NIDDK NIH HHS/ -- England -- Nature. 2012 Sep 27;489(7417):561-5. doi: 10.1038/nature11499.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biology, University of Florida, Gainesville, Florida 32610, USA. seifert@ufl.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23018966" target="_blank"〉PubMed〈/a〉
    Keywords: Adipose Tissue/physiology ; Animals ; Cartilage/physiology ; Cicatrix ; Collagen Type III/metabolism ; Dermis/physiology ; Ear, External/physiology ; Extracellular Matrix/metabolism ; Female ; Hair Follicle/physiology ; Kenya ; Male ; Models, Animal ; Murinae/injuries/*physiology ; Porosity ; Regeneration/*physiology ; Sebaceous Glands/physiology ; Skin/cytology/*injuries ; *Skin Physiological Phenomena ; Urodela/physiology ; Wound Healing/physiology
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 4
    Publication Date: 2008-01-12
    Description: Mutualisms are key components of biodiversity and ecosystem function, yet the forces maintaining them are poorly understood. We investigated the effects of removing large mammals on an ant-Acacia mutualism in an African savanna. Ten years of large-herbivore exclusion reduced the nectar and housing provided by plants to ants, increasing antagonistic behavior by a mutualistic ant associate and shifting competitive dominance within the plant-ant community from this nectar-dependent mutualist to an antagonistic species that does not depend on plant rewards. Trees occupied by this antagonist suffered increased attack by stem-boring beetles, grew more slowly, and experienced doubled mortality relative to trees occupied by the mutualistic ant. These results show that large mammals maintain cooperation within a widespread symbiosis and suggest complex cascading effects of megafaunal extinction.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Palmer, Todd M -- Stanton, Maureen L -- Young, Truman P -- Goheen, Jacob R -- Pringle, Robert M -- Karban, Richard -- New York, N.Y. -- Science. 2008 Jan 11;319(5860):192-5. doi: 10.1126/science.1151579.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Zoology, University of Florida, Gainesville, FL 32611, USA. tmpalmer@zoo.ufl.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18187652" target="_blank"〉PubMed〈/a〉
    Keywords: *Acacia/anatomy & histology/growth & development ; Animals ; *Ants/physiology ; Beetles ; Behavior, Animal ; *Ecosystem ; *Elephants ; Insects ; Kenya ; *Ruminants ; *Symbiosis
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 5
    Publication Date: 2014-10-18
    Description: Understanding how predation risk and plant defenses interactively shape plant distributions is a core challenge in ecology. By combining global positioning system telemetry of an abundant antelope (impala) and its main predators (leopards and wild dogs) with a series of manipulative field experiments, we showed that herbivores' risk-avoidance behavior and plants' antiherbivore defenses interact to determine tree distributions in an African savanna. Well-defended thorny Acacia trees (A. etbaica) were abundant in low-risk areas where impala aggregated but rare in high-risk areas that impala avoided. In contrast, poorly defended trees (A. brevispica) were more abundant in high- than in low-risk areas. Our results suggest that plants can persist in landscapes characterized by intense herbivory, either by defending themselves or by thriving in risky areas where carnivores hunt.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ford, Adam T -- Goheen, Jacob R -- Otieno, Tobias O -- Bidner, Laura -- Isbell, Lynne A -- Palmer, Todd M -- Ward, David -- Woodroffe, Rosie -- Pringle, Robert M -- New York, N.Y. -- Science. 2014 Oct 17;346(6207):346-9. doi: 10.1126/science.1252753.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Zoology, University of British Columbia, Vancouver, BC, Canada. Mpala Research Centre, Post Office Box 555, Nanyuki, Kenya. atford@zoology.ubc.ca. ; Mpala Research Centre, Post Office Box 555, Nanyuki, Kenya. Department of Zoology and Physiology, University of Wyoming, Laramie, WY, USA. ; Mpala Research Centre, Post Office Box 555, Nanyuki, Kenya. ; Mpala Research Centre, Post Office Box 555, Nanyuki, Kenya. Department of Anthropology, University of California, Davis, CA, USA. ; Mpala Research Centre, Post Office Box 555, Nanyuki, Kenya. Department of Biology, University of Florida, Gainesville, FL, USA. ; School of Life Sciences, University of KwaZulu-Natal, Scottsville, South Africa. ; Mpala Research Centre, Post Office Box 555, Nanyuki, Kenya. Institute of Zoology, Zoological Society of London, Regent's Park, London, UK. ; Mpala Research Centre, Post Office Box 555, Nanyuki, Kenya. Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25324387" target="_blank"〉PubMed〈/a〉
    Keywords: *Acacia ; Animals ; *Antelopes ; *Canidae ; *Food Chain ; Geographic Information Systems ; *Herbivory ; *Panthera ; *Predatory Behavior ; *Trees
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 6
    Publication Date: 2015-07-18
    Description: The search for predictions of species diversity across environmental gradients has challenged ecologists for decades. The humped-back model (HBM) suggests that plant diversity peaks at intermediate productivity; at low productivity few species can tolerate the environmental stresses, and at high productivity a few highly competitive species dominate. Over time the HBM has become increasingly controversial, and recent studies claim to have refuted it. Here, by using data from coordinated surveys conducted throughout grasslands worldwide and comprising a wide range of site productivities, we provide evidence in support of the HBM pattern at both global and regional extents. The relationships described here provide a foundation for further research into the local, landscape, and historical factors that maintain biodiversity.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Fraser, Lauchlan H -- Pither, Jason -- Jentsch, Anke -- Sternberg, Marcelo -- Zobel, Martin -- Askarizadeh, Diana -- Bartha, Sandor -- Beierkuhnlein, Carl -- Bennett, Jonathan A -- Bittel, Alex -- Boldgiv, Bazartseren -- Boldrini, Ilsi I -- Bork, Edward -- Brown, Leslie -- Cabido, Marcelo -- Cahill, James -- Carlyle, Cameron N -- Campetella, Giandiego -- Chelli, Stefano -- Cohen, Ofer -- Csergo, Anna-Maria -- Diaz, Sandra -- Enrico, Lucas -- Ensing, David -- Fidelis, Alessandra -- Fridley, Jason D -- Foster, Bryan -- Garris, Heath -- Goheen, Jacob R -- Henry, Hugh A L -- Hohn, Maria -- Jouri, Mohammad Hassan -- Klironomos, John -- Koorem, Kadri -- Lawrence-Lodge, Rachael -- Long, Ruijun -- Manning, Pete -- Mitchell, Randall -- Moora, Mari -- Muller, Sandra C -- Nabinger, Carlos -- Naseri, Kamal -- Overbeck, Gerhard E -- Palmer, Todd M -- Parsons, Sheena -- Pesek, Mari -- Pillar, Valerio D -- Pringle, Robert M -- Roccaforte, Kathy -- Schmidt, Amanda -- Shang, Zhanhuan -- Stahlmann, Reinhold -- Stotz, Gisela C -- Sugiyama, Shu-ichi -- Szentes, Szilard -- Thompson, Don -- Tungalag, Radnaakhand -- Undrakhbold, Sainbileg -- van Rooyen, Margaretha -- Wellstein, Camilla -- Wilson, J Bastow -- Zupo, Talita -- New York, N.Y. -- Science. 2015 Jul 17;349(6245):302-5. doi: 10.1126/science.aab3916.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Natural Resource Sciences, Thompson Rivers University, Kamloops, BC, Canada. lfraser@tru.ca. ; Department of Biology, University of British Columbia, Okanagan campus, Kelowna, BC, Canada. ; Department of Disturbance Ecology, BayCEER, Uni- versity of Bayreuth, Bayreuth, Germany. ; Department of Molecular Biology and Ecology of Plants, Tel Aviv University, Tel-Aviv, Israel. ; Department of Botany, Institute of Ecology and Earth Sciences, University of Tartu, Tartu, Estonia. ; Faculty of Natural Resources College of Agriculture and Natural Resources, University of Tehran, Iran. ; MTA Centre for Ecological Research, Institute of Ecology and Botany, Vacratot, Hungary, and School of Plant Biology, University of Western Australia, Crawley, Australia. ; Department of Biogeography, BayCEER, University of Bayreuth, Bayreuth, Germany. ; Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada. ; Department of Ecology and Evolutionary Biology, University of Kansas, Manhattan, KS 66047, USA. ; Department of Biology, National University of Mongolia, Ulaanbaatar, Mongolia. ; Department of Botany, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil. ; Department of Agricultural, Food and Nutritional Sciences, University of Alberta, Edmonton, AB, Canada. ; Applied Behavioural Ecology and Ecosystem Research Unit, University of South Africa, Johannesberg, South Africa. ; Instituto Multidisciplinario de Biologia Vegetal (IMBIV-CONICET) and Facultad de Ciencias Exactas, Fisicas y Naturales, Universidad Nacional de Cordoba, Cordoba, Espana. ; School of Biosciences and Veterinary Medicine, University of Camerino, Camerino, Italy. ; School of Natural Sciences, Trinity College Dublin, Dublin, Ireland. ; Departamento de Botanica, UNESP - Univ. Estadual Paulista, Rio Claro, Brazil. ; Department of Biology, Syracuse University, Syracuse, NY 13210, USA. ; Department of Biology, University of Akron, Akron, OH 44325, USA. ; Department of Zoology and Physiology, University of Wyoming, Laramie, WY 82071, USA. ; Department of Biology, University of Western Ontario, London, ON, Canada. ; Department of Botany, Corvinus University of Budapest, Budapest, Hungary. ; Department of Natural Resources, Islamic Azad University, Nour Branch, Iran. ; Department of Botany, University of Otago, Dunedin, New Zealand. ; International Centre for Tibetan Plateau Ecosystem Management, Lanzhou University, Lanzhou, China. ; Institute of Plant Sciences, University of Bern, Altenbergrain 21, CH-3013, Bern, Switzerland. ; Department of Ecology, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil. ; Faculty of Agronomy, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil. ; Department of Range and Watershed Management, Ferdowsi University of Mashhad, Iran. ; Department of Biology, University of Florida, Gainesville, FL 32611, USA. ; Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544, USA. ; Department of Natural Resource Sciences, Thompson Rivers University, Kamloops, BC, Canada. ; Laboratory of Plant Ecology, Hirosaki University, Hirosaki, Japan. ; Institute of Plant Production, Szent Istvan University, Godollo, Hungary. ; Agriculture and Agri-Food Canada, Lethbridge Research Centre, Lethbridge, AB, Canada. ; Department of Plant Science, University of Pretoria, Pretoria, South Africa. ; Faculty of Science and Technology, Free University of Bozen-Bolzano, Bolzano, Italy. ; Department of Botany, University of Otago, Dunedin, New Zealand. Landcare Research, Dunedin, New Zealand.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26185249" target="_blank"〉PubMed〈/a〉
    Keywords: *Biodiversity ; Biomass ; *Grassland ; *Plant Development ; Stress, Physiological
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 7
    Publication Date: 2013-11-22
    Description: Regulation of cell survival by sphingosine-1-phosphate receptor S1P1 via reciprocal ERK-dependent suppression of Bim and PI-3-kinase/protein kinase C-mediated upregulation of Mcl-1 Cell Death and Disease 4, e927 (November 2013). doi:10.1038/cddis.2013.455 Authors: C Rutherford, S Childs, J Ohotski, L McGlynn, M Riddick, S MacFarlane, D Tasker, S Pyne, N J Pyne, J Edwards & T M Palmer
    Keywords: sphingosine-1-phosphateS1P1apoptosisMcl-1Bimbreast cancer
    Electronic ISSN: 2041-4889
    Topics: Biology , Medicine
    Published by Springer Nature
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Oecologia 123 (2000), S. 425-435 
    ISSN: 1432-1939
    Keywords: Key words Species coexistence ; Dominance hierarchy ; Acacia drepanolobium ; Crematogaster ; Tetraponera
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  In monospecific stands of Acacia drepanolobium in Laikipia, Kenya, virtually all but the smallest trees are occupied by one of four species of ants. Although trees are a limiting resource, all four ant species are maintained in this system. Three separate lines of evidence confirm a linear dominance hierarchy among these four ants: (1) experimentally staged conflicts, (2) natural transitions among 1773 tagged trees over a 6-month period, and (3) the average sizes of trees occupied by ants of different species. Short-term dynamics during a drying period reveal that many smaller trees (〈1 m) occupied by dominant ants were subsequently abandoned, and that abandoned trees had grown more slowly than those that were not abandoned. Height growth increments over 6 months were generally independent of ant occupant, but increased with tree height. Among taller trees (〉1 m), changes in ant occupation congruent with the dominance hierarchy (i.e., transitions from more subordinate ant species to more dominant ant species) occurred on trees that grew faster than average. In contrast, the (less frequent) changes in ant occupation ”against” the direction of the dominance hierarchy occurred on trees that grew more slowly than average. Observed correlations between tree vigor and takeover direction suggest that colony growth of dominant ant species is either favored in more productive microhabitats, or that such colonies differentially seek out healthier trees for conquest. Colonies of dominant species may differentially abandon more slowly growing trees during (dry) periods of retrenchment, or suffer higher mortality on these trees. Subordinate ant species appear to move onto these abandoned trees and, to a lesser extent, colonize new recruits in the sapling class. These data reveal that within a simple linear dominance hierarchy, short-term variations exist that may reveal underlying mechanisms associated with coexistence.
    Type of Medium: Electronic Resource
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  • 9
  • 10
    Publication Date: 2014-09-24
    Description: Under anaerobic conditions, Escherichia coli can carry out a mixed-acid fermentation that ultimately produces molecular hydrogen. The enzyme directly responsible for hydrogen production is the membrane-bound formate hydrogenlyase (FHL) complex, which links formate oxidation to proton reduction and has evolutionary links to Complex I, the NADH:quinone oxidoreductase. Although the genetics,...
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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