Homogenization of periodic auxetic materials

International audienceMaterials presenting a negative Poisson's ratio (auxetics) have drawn attention for the past two decades, especially in the field of lightweight composite structures and cellular materials. Studies have shown that auxeticity may result in higher shear modulus, fracture toughness and acoustic damping. In this work, three auxetic periodic lattices are considered. Elastic moduli are computed and anisotropy is investigated by the use of finite element method combined with numerical homogenization technique

Toward unifying global hotspots of wild and domesticated biodiversity

Global biodiversity hotspots are areas containing high levels of species richness, endemism and threat. Similarly, regions of agriculturally relevant diversity have been identified where many domesticated plants and animals originated, and co-occurred with their wild ancestors and relatives. The agro-biodiversity in these regions has, likewise, often been considered threatened. Biodiversity and agro-biodiversity hotspots partly overlap, but their geographic intricacies have rarely been investigated together. Here we review the history of these two concepts and explore their geographic relationship by analysing global distribution and human use data for all plants, and for major crops and associated wild relatives.We highlight a geographic continuum between agro-biodiversity hotspots that contain high richness in species that are intensively used and well known by humanity (i.e., major crops and most viewed species onWikipedia) and biodiversity hotspots encompassing species that are less heavily used and documented (i.e., crop wild relatives and species lacking information on Wikipedia). Our contribution highlights the key considerations needed for further developing a unifying concept of agro-biodiversity hotspots that encompasses multiple facets of diversity (including genetic and phylogenetic) and the linkage with overall biodiversity. This integration will ultimately enhance our understanding of the geography of human-plant interactions and help guide the preservation of nature and its contributions to people

Synthesizing the scientific evidence to inform the development of the post-2020 Global Framework on Biodiversity

Fil: Díaz, Sandra. Universidad Nacional de Córdoba; Argentina.Fil: Broadgate, Wendy. Future Earth; Suecia.Fil: Declerck, Fabrice. Bioversity International; Italia.Fil: Dobrota, Susanna. Future Earth; Suecia.Fil: Krug, Cornelia. bioDISCOVERY; Suecia.Fil: Moersberg, Hannah. Future Earth; Francia.Fil: Obura, David. Coastal Oceans Research and Development – Indian Ocean; Kenya.Fil: Spehn, Eva. Forum Biodiversity; Suiza.Fil: Tewksbury, Joshua. Future Earth; Estados Unidos.Fil: Verburg, Peter. Vrije Universiteit Amsterdam; Países Bajos.Fil: Zafra Calvo, Noelia. Future Earth; Suecia.Fil: Bellon, Mauricio. Comisión Nacional para el Conocimiento y Uso de la Biodiversidad; México.Fil: Burgess, Neil. United Nations Environment Programme World Conservation Monitoring Centre; Reino Unido.Fil: Cariño, Joji. Forest Peoples Programme; Reino Unido.Fil: Castañeda Alvarez, Nora. Global Crop Diversity Trust; Alemania.Fil: Cavender-Bares, Jeannine. University of Minnesota; Estados Unidos.Fil: Chaplin Kramer, Rebecca. Stanford University; Estados Unidos.Fil: De Meester, Luc. Katholieke Universiteit Leuven; Bélgica.Fil: Dulloo, Ehsan. Consultative Group for International Agricultural Research; Francia.Fil: Fernández-Palacios, José María. Universidad de La Laguna; España.Fil: Garibaldi, Lucas A. Universidad Nacional de Río Negro. Instituto de Investigaciones en Recursos Naturales, Agroecología y Desarrollo Rural; Argentina.Fil: Garibaldi, Lucas A. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Recursos Naturales, Agroecología y Desarrollo Rural; Argentina.Fil: Hill, Samantha. United Nations Environment Programme World Conservation Monitoring Centre; Reino Unido.Fil: Isbell, Forest. University of Minnesota; Estados Unidos.Fil: Leadley, Paul. Université Paris-Saclay; Francia.Fil: Liu, Jianguo. Michigan State University; Estados Unidos.Fil: Mace, Georgina M. University College London; Reino Unido.Fil: Maron, Martine. The University of Queensland; Australia.Fil: Martín-López, Berta. Leuphana University Lüneburg; Alemania.Fil: McGowan, Philip. University of Newcastle; Australia.Fil: Pereira, Henrique. German Centre for Integrative Biodiversity Research; Alemania.Fil: Purvis, Andy. Imperial College London. Grand Challenges in Ecosystems and the Environment; Reino Unido.Fil: Reyes-García, Victoria. Universidad Autónoma de Barcelona; España.Fil: Rocha, Juan. Future Earth; Suecia.Fil: Rondinini, Carlo. Sapienza-Università di Roma; Italia.Fil: Shannon, Lynne. University of Cape Town; Sudáfrica.Fil: Shaw, Rebecca. World Wildlife Fund; Estados Unidos.Fil: Shin, Yunne Jai. University of Cape Town. Marine Research Institute. Department of Biological Sciences; Sudáfrica.Fil: Snelgrove, Paul. Memorial University of Newfoundland; Canadá.Fil: Strassburg, Bernardo. International Institute for Sustainability; Brasil.Fil: Subramanian, Suneetha.United Nations University; Japón.Fil: Visconti, Piero. International Institute for Applied Systems Analysis; Austria.Fil: Watson, James. Wildlife Conservation Society; Estados Unidos.Fil: Zanne, Amy. The George Washington University; Estados Unidos.Fil: Bruford, Michael. Cardiff University; Gales.Fil: Colli, Licia. Università Cattolica del Sacro Cuore; Italia.Fil: Azeredo de Dornelas, Maria. University of St Andrews; Escocia.Fil: Bascompte, Jordi. Universität Zürich; Suiza.Fil: Forest, Felix. Royal Botanic Gardens; Reino Unido.Fil: Hoban, Sean. The Morton Arboretum; Estados Unidos.Fil: Jones, Sarah. Consultative Group for International Agricultural Research; Francia.Fil: Jordano, Pedro. Consejo Superior de Investigaciones Científicas; España.Fil: Kassen, Rees. University of Ottawa; Canadá.Fil: Khoury, Colin. Consultative Group for International Agricultural Research; Francia.Fil: Laikre, Linda. Stockholms Universitet; Suecia.Fil: Maxted, Nigel. University of Birmingham; Reino Unido.Fil: Miloslavich, Patricia. Universidad Simón Bolívar; Venezuela.Fil: Moreno Mateos, David. Basque Centre for Climate Change; España.Fil: Ogden, Rob. The University of Edinburgh; Reino Unido.Fil: Segelbacher, Gernot. Albert-Ludwigs-Universität Freiburg; Alemania.Fil: Souffreau, Caroline. Katholieke Universiteit Leuven; Bélgica.Fil: Svenning, Jens Christian. Aarhus University; Dinamarca.Fil: Vázquez, Ella. Universidad Nacional Autónoma de México; México.This report is the result of a meeting which aimed to offer scientific guidance to the development under the Convention on Biological Diversity (CBD) of the post-2020 Global Biodiversity Framework focussing on its contribution to the 2030 Mission and 2050 Vision. We provide a synthesis of the scientific and technical justification, evidence base and feasibility for outcome-oriented goals on nature and its contributions to people, including biodiversity at different levels from genes to biomes. The report is structured to respond to the Zero Draft of the post-2020 Global Biodiversity Framework

Integrating community assembly and biodiversity to better understand ecosystem function: the Community Assembly and the Functioning of Ecosystems (CAFE) approach.

The research of a generation of ecologists was catalysed by the recognition that the number and identity of species in communities influences the functioning of ecosystems. The relationship between biodiversity and ecosystem functioning (BEF) is most often examined by controlling species richness and randomising community composition. In natural systems, biodiversity changes are often part of a bigger community assembly dynamic. Therefore, focusing on community assembly and the functioning of ecosystems (CAFE), by integrating both species richness and composition through species gains, losses and changes in abundance, will better reveal how community changes affect ecosystem function. We synthesise the BEF and CAFE perspectives using an ecological application of the Price equation, which partitions the contributions of richness and composition to function. Using empirical examples, we show how the CAFE approach reveals important contributions of composition to function. These examples show how changes in species richness and composition driven by environmental perturbations can work in concert or antagonistically to influence ecosystem function. Considering how communities change in an integrative fashion, rather than focusing on one axis of community structure at a time, will improve our ability to anticipate and predict changes in ecosystem function

Madagascar’s extraordinary biodiversity: Evolution, distribution, and use

Madagascar's biota is hyperdiverse and includes exceptional levels of endemicity. We review the current state of knowledge on Madagascar's past and current terrestrial and freshwater biodiversity by compiling and presenting comprehensive data on species diversity, endemism, and rates of species description and human uses, in addition to presenting an updated and simplified map of vegetation types. We report a substantial increase of records and species new to science in recent years; however, the diversity and evolution of many groups remain practically unknown (e.g., fungi and most invertebrates). Digitization efforts are increasing the resolution of species richness patterns and we highlight the crucial role of field- and collections-based research for advancing biodiversity knowledge and identifying gaps in our understanding, particularly as species richness corresponds closely to collection effort. Phylogenetic diversity patterns mirror that of species richness and endemism in most of the analyzed groups. We highlight humid forests as centers of diversity and endemism because of their role as refugia and centers of recent and rapid radiations. However, the distinct endemism of other areas, such as the grassland-woodland mosaic of the Central Highlands and the spiny forest of the southwest, is also biologically important despite lower species richness. The documented uses of Malagasy biodiversity are manifold, with much potential for the uncovering of new useful traits for food, medicine, and climate mitigation. The data presented here showcase Madagascar as a unique living laboratory for our understanding of evolution and the complex interactions between people and nature. The gathering and analysis of biodiversity data must continue and accelerate if we are to fully understand and safeguard this unique subset of Earth's biodiversity

Madagascar’s extraordinary biodiversity: Threats and opportunities

Madagascar's unique biota is heavily affected by human activity and is under intense threat. Here, we review the current state of knowledge on the conservation status of Madagascar's terrestrial and freshwater biodiversity by presenting data and analyses on documented and predicted species-level conservation statuses, the most prevalent and relevant threats, ex situ collections and programs, and the coverage and comprehensiveness of protected areas. The existing terrestrial protected area network in Madagascar covers 10.4% of its land area and includes at least part of the range of the majority of described native species of vertebrates with known distributions (97.1% of freshwater fishes, amphibians, reptiles, birds, and mammals combined) and plants (67.7%). The overall figures are higher for threatened species (97.7% of threatened vertebrates and 79.6% of threatened plants occurring within at least one protected area). International Union for Conservation of Nature (IUCN) Red List assessments and Bayesian neural network analyses for plants identify overexploitation of biological resources and unsustainable agriculture as themost prominent threats to biodiversity. We highlight five opportunities for action at multiple levels to ensure that conservation and ecological restoration objectives, programs, and activities take account of complex underlying and interacting factors and produce tangible benefits for the biodiversity and people of Madagascar