Internal Migration in Mexico: Consolidation of Urban–Urban Mobility, 2000–2015          下载免费PDF全文

Enrique Pérez‐Campuzano  Guillermo Castillo Ramírez  Mateo Carlos Galindo Pérez 《Growth and change》2018,49(1):223-240

Internal migration has been recognized as the major influence in terms of population redistribution across urban systems, but it is not a homogeneous phenomenon. Within the context of internal rural‐urban migration decline and the negative changes in migratory balances in the metropolitan area of Mexico City, the core of enquiry in this paper is the approach to growth and consolidation of an internal urban–urban migration system in the early twenty‐first century (2000–2015). This process has taken place through two main networks, among metropolitan areas not corresponding to the principal city and among intermediate cities. Internal migration is a complex process that involves both individual and spatial characteristics and which leads to spatially uneven development in the long term. Data from three censuses of the population of Mexico (2000, 2010, and 2015) show a transition to a more urban–urban migration pattern, with skilled migrants tending to have metropolitan and urban destinations, whereas less‐skilled migrants prefer rural and small urban destinations.  相似文献   

Empowering high seas governance with satellite vessel tracking data          下载免费PDF全文

Daniel C Dunn  Caroline Jablonicky  Guillermo O Crespo  Douglas J McCauley  David A Kroodsma  Kristina Boerder  Kristina M Gjerde  Patrick N Halpin 《Fish and Fisheries》2018,19(4):729-739

Between 1950 and 1989, marine fisheries catch in the open‐ocean and deep‐sea beyond 200 nautical miles from shore increased by a factor of more than 10. While high seas catches have since plateaued, fishing effort continues to increase linearly. The combination of increasing effort and illegal, unreported and unregulated (IUU) fishing has led to overfishing of target stocks and declines in biodiversity. To improve management, there have been numerous calls to increase monitoring, control and surveillance (MCS). However, MCS has been unevenly implemented, undermining efforts to sustainably use high seas and straddling stocks and protect associated species and ecosystems. The United Nations General Assembly is currently negotiating a new international treaty for the conservation and sustainable use of biodiversity beyond national jurisdiction (BBNJ). The new treaty offers an excellent opportunity to address discrepancies in how MCS is applied across regional fisheries management organizations (RFMOs). This paper identifies ways that automatic identification system (AIS) data can inform MCS on the high seas and thereby enhance conservation and management of biodiversity beyond national jurisdictions. AIS data can be used to (i) identify gaps in governance to underpin the importance of a holistic scope for the new agreement; (ii) monitor area‐based management tools; and (iii) increase the capacity of countries and RFMOs to manage via the technology transfer. Any new BBNJ treaty should emphasize MCS and the role of electronic monitoring including the use of AIS data, as well as government–industry–civil society partnerships to ensure critically important technology transfer and capacity building.  相似文献   

Mechanisms of glyphosate resistance and response to alternative herbicide‐based management in populations of the three Conyza species introduced in southern Spain          下载免费PDF全文

Ignacio Amaro‐Blanco  Pablo Tomás Fernández‐Moreno  María Dolores Osuna‐Ruiz  Fernando Bastida  Rafael De Prado 《Pest management science》2018,74(8):1925-1937

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Recirculation nursery systems for bivalves     

Pauline Kamermans  Ainhoa Blanco  Sandra Joaquim  Domitília Matias  Thorolf Magnesen  Jean Louis Nicolas  Bruno Petton  Rene Robert 《Aquaculture International》2016,24(3):827-842

In order to increase production of bivalves in hatcheries and nurseries, the development of new technology and its integration into commercial bivalve hatcheries is important. Recirculation aquaculture systems (RASs) have several advantages: high densities of the species can be cultured resulting in a cost-effective production system; optimal temperature maximizes production and allows rapid turnover of the product; stable water quality improves growth rate and minimizes stress and potential loss by diseases. Pilot RAS systems were developed for seed rearing of oysters (Crassostrea gigas), scallops (Pecten maximus), mussels (Mytilus edulis) and clams (Ruditapes decussatus). Optimal feed addition and waste matrix were determined. Based on this, system flow rates were designed. Seed growth in the pilot RAS systems was compared at different renewal rates and with growth in flow-through systems (FTS). All four species can be reared in RAS and showed similar growth in RAS and in FTS or in RAS with a higher renewal rate. RAS can keep O₂, nitrogen and pH within the desired range. Temperature was generally higher in RAS than in FTS, probably due to heat induced by the pump circulating the water. The supply of sufficient amount of food in combination with a desire to reduce the renewal rate calls for use of concentrated feed in RAS.  相似文献   

A review of silvopastoral systems in native forests of Nothofagus antarctica in southern Patagonia,Argentina     

Pablo Luis Peri  Héctor A. Bahamonde  María V. Lencinas  Verónica Gargaglione  Rosina Soler  Sebastián Ormaechea  Guillermo Martínez Pastur 《Agroforestry Systems》2016,90(6):933-960

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Impact of Teratosphaeria nubilosa over tree growth and survival of Eucalyptus globulus and Eucalyptus maidenii in Uruguay     

Gustavo Balmelli  Sofía Simeto  Diego Torres  Andrés Hirigoyen  Alicia Castillo  Nora Altier  Guillermo Pérez  Julio J. Diez 《New Forests》2016,47(6):829-843

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Genetic architecture of plant height in maize phenotype‐selected introgression families          下载免费PDF全文

Adel H. Abdel‐Ghani  Songlin Hu  Yongsheng Chen  Everton A. Brenner  Bharath Kumar  Michael Blanco  Thomas Lübberstedt 《Plant Breeding》2016,135(4):429-438

This study aimed at developing, characterizing and evaluating two maize phenotypic‐selected introgression libraries for a collection of dominant plant height (PHT)‐increasing alleles by introgressing donor chromosome segments (DCS) from Germplasm Enhancement of Maize (GEM) accessions into elite inbred lines: PHB47 and PHZ51. Different backcross generations (BC₁‐BC₄) were developed and the tallest 23 phenotype‐selected introgression families (PIFs) from each introgression library (PHB47 or PHZ51) were selected for single nucleotide polymorphism genotyping to localize DCS underlying PHT. The result shows that most PIFs carrying DCS were significantly (α = 0.01) taller than the respective recurrent parent. In addition, they contained larger donor genome proportions than expected in the absence of selection or random mating across all BC generations. The DCS were distributed over the whole genome, indicating a complex genetic nature underlying PHT. We conclude that our PIFs are enriched for favourable PHT‐increasing alleles. These two libraries offer opportunities for future PHT gene isolation and allele characterization and for breeding purposes, such as novel cultivars for biofuel production.  相似文献   

Natural Enemies of the Frankliniella Complex Species (Thysanoptera: Thripidae) in Ataulfo Mango Agroecosystems     

Franklin H. Rocha  Francisco Infante  Alfredo Castillo  Guillermo Ibarra-Nu?ez  Arturo Goldarazena  Joe E. Funderburk 《Journal of insect science (Online)》2015,15(1)

A field survey was conducted in Ataulfo mango (Mangifera indica L.) orchards in Chiapas, Mexico, with the objective of determining the natural enemies of the Frankliniella complex species (Thysanoptera: Thripidae). Seven species of this genus feed and reproduce in large numbers during the mango flowering. Two representative orchards were selected: the orchard “Tres A” characterized by an intensive use of agrochemicals directed against thrips, and the orchard “La Escondida” that did not spray insecticides. During mango flowering, five inflorescences were randomly collected every 5 d in both orchards, for a total of 18 sampling dates. Results revealed the presence of 18 species of arthropods that were found predating on Frankliniella. There were 11 species in the families Aeolothripidae, Phlaeothripidae, Formicidae, Anthocoridae and Chrysopidae; and seven species of spiders in the families Araneidae, Tetragnathidae, and Uloboridae. Over 88% of predators were anthocorids, including, Paratriphleps sp. (Champion), Orius insidiosus (Say), Orius tristicolor (White), and O. perpunctatus (Reuter). The orchard that did not spray insecticides had a significantly higher number of predators suggesting a negative effect of the insecticides on the abundance of these organisms.  相似文献   

Tetrodotoxin,an Extremely Potent Marine Neurotoxin: Distribution,Toxicity, Origin and Therapeutical Uses     

Jorge Lago  Laura P. Rodríguez  Lucía Blanco  Juan Manuel Vieites  Ana G. Cabado 《Marine drugs》2015,13(10):6384-6406

Tetrodotoxin (TTX) is a potent neurotoxin responsible for many human intoxications and fatalities each year. The origin of TTX is unknown, but in the pufferfish, it seems to be produced by endosymbiotic bacteria that often seem to be passed down the food chain. The ingestion of contaminated pufferfish, considered the most delicious fish in Japan, is the usual route of toxicity. This neurotoxin, reported as a threat to human health in Asian countries, has spread to the Pacific and Mediterranean, due to the increase of temperature waters worldwide. TTX, for which there is no known antidote, inhibits sodium channel producing heart failure in many cases and consequently death. In Japan, a regulatory limit of 2 mg eq TTX/kg was established, although the restaurant preparation of “fugu” is strictly controlled by law and only chefs qualified are allowed to prepare the fish. Due to its paralysis effect, this neurotoxin could be used in the medical field as an analgesic to treat some cancer pains.  相似文献   

Effects of habitat degradation on the abundance, richness and diversity of raptors across Neotropical biomes     

Martina Carrete  Jos L. Tella  Guillermo Blanco  Marcelo Bertellotti 《Biological conservation》2009,142(10):2002-2011

Population growth and human development result in biodiversity loss and biological homogenization not only in developed countries, but increasingly in the less developed countries as well. In those countries, where urbanization and agricultural intensification occur at a faster rate than in developed countries, habitat degradation appears to be the leading cause of wildlife loss. During the breeding seasons of 2002–2005 we conducted road surveys across five biomes of Argentina to detect variations in raptor community attributes as potential indicators of broad scale habitat degradation. Abundance of individuals, richness and diversity of species were calculated to assess the effects of habitat transformation and patch size on these community attributes. Raptor communities strongly varied in relation to habitat transformations, with lower abundance of individuals, richness and diversity of species in more transformed landscapes. Small patches of natural vegetation and locations in which natural and cultivated lands where interspersed showed lower richness and diversity of raptors than large patches. Fragmentation was the main cause of reductions in abundance of individuals. Although the relative contribution of our two estimates of habitat degradation to abundance, richness and diversity of raptors varied among biomes, these community attributes proved useful as predictors of habitat degradation. This was especially true in habitats where raptor communities are more complex although overall patterns remained constant across biomes, from forests to deserts. Taking into account current trends of habitat transformation (drastic increments in monocultures, urban areas, and habitat patchiness), the conservation of raptor communities in these biomes could be seriously compromised. In terms of species-specific responses of raptors to habitat degradation, a rapid process of homogenization can be expected, resulting in only a few winner species within a general scenario of losers.  相似文献