14 resultados para Migrations
Resumo:
Freedom to provide services - Nationals of a non-member country - Posted Workers
Resumo:
This volume explores the role and history of migration and diaspora within the Portuguese empire, investigating what role colonial communities and diaspora have had in shaping the Portuguese empire and its heritage. The book consists of twelve case studies which look at topics such as Portuguese migration to Africa, the Ismaili and the Swiss presence in Mozambique, the Goanese in East Africa, the Chinese in Brazil, and the history of the African presence in Portugal.
Resumo:
Before the mass migrations from Ireland in the nineteenth century, earlier waves of migration in the eighteenth century saw significant numbers of people leave Ireland, predominantly from Ulster, to settle in North America. This article, using as its principal data source the Belfast News Letter ( BNL), its letters, advertisements and reports, focuses firstly on reconstructing the late eighteenth-century migration process and voyage, highlighting the barriers represented by the Atlantic Ocean. In addition to the challenges of the sea, there were problems with the ships, the ever-present danger of disease and also threats from other vessels, from privateers to press gangs. The voyage was recognized as a ‘universal dread’, and the risks taken to ‘dare the boist’rous main’ were perhaps not minimized in the pages of the BNL, whose editorial stance was antipathetic to the migration for the potential harm it caused to Ulster by removing so many of its industrious young. The second part of this article goes on to consider the newspaper’s and others’ vested interests in the emigration process, demonstrates how these were manifested in the press and sets the coverage of this very significant early emigration flow within the context of contemporary religious and colonial discourses at a period of very lively transatlantic interactions.
Resumo:
During January 2003 the bathymetric distribution of the cephalopod fauna of the South Georgia and Shag Rocks slope (100-900 m) was investigated using a commercial bottom trawl. Forty-four trawl stations caught 193 cephalopod specimens including six species of octopod and seven of squid. The benthic octopods Pareledone turqueti and Adelieledone polymorpha were abundant in shallow water at South Georgia, being replaced by Thaumeledone gunteri in greater depths. However, neither A. polymorpha nor T gunteri were caught on the adjacent Shag Rocks area. Two specimens of the deep-sea genus Graneledone were caught on the South Georgia slope. The most abundant squid species caught were Moroteuthis knipovitchi, Psychroteuthis glacialis and Slosarczykovia circumantarctica, which are primarily pelagic and may have been taken when their vertical migrations impinged on the slope.
Resumo:
How do the predicted climatic changes (IPCC, 2007) for the next century compare in magnitude and rate to those that Earth has previously encountered? Are there comparable intervals of rapid rates of temperature change, sea-level rise and levels of atmospheric CO2 that can be used as analogues to assess possible biotic responses to future change? Or are we stepping into the great unknown? This perspective article focuses on intervals in time in the fossil record when atmospheric CO2 concentrations increased up to 1200 ppmv, temperatures in mid- to high-latitudes increased by greater than 4 ?C within 60 years, and sea levels rose by up to 3 m higher than present. For these intervals in time, case studies of past biotic responses are presented to demonstrate the scale and impact of the magnitude and rate of such climate changes on biodiversity. We argue that although the underlying mechanisms responsible for these past changes in climate were very different (i.e. natural processes rather than anthropogenic), the rates and magnitude of climate change are similar to those predicted for the future and therefore potentially relevant to understanding future biotic response. What emerges from these past records is evidence for rapid community turnover, migrations, development of novel ecosystems and thresholds from one stable ecosystem state to another, but there is very little evidence for broad-scale extinctions due to a warming world. Based on this evidence from the fossil record, we make four recommendations for future climate-change integrated conservation strategies.
Resumo:
European anchovy (Engraulis encrasicolus) and sardine (Sardina pilchardus) are southern, warm water species that prefer temperatures warmer than those found in boreal waters. After about 40 years of absence, they were again observed in the 1990s in increasing quantities in the North Sea and the Baltic Sea. Whereas global warming probably played a role in these northward migrations, the North Atlantic Oscillation (NAO), the Atlantic Multidecadal Oscillation (AMO) and the contraction of the subpolar gyre were important influences. Sardine re-invaded the North Sea around 1990, probably mainly as a response to warmer temperatures associated with the strengthening of the NAO in the late 1980s. However, increasing numbers of anchovy eggs, larvae, juveniles and adults have been recorded only since the mid-1990s, when, particularly, summer temperatures started to increase. This is probably a result of the complex dynamics of ocean–atmosphere coupling involving changes in North Atlantic current structures, such as the contraction of the subpolar gyre, and dynamics of AMO. Apparently, climate variability drives anchovies and sardines into the North and Baltic Seas. Here, we elucidate the climatic background of the return of anchovies and sardines to the northern European shelf seas and the changes in the North Sea fish community in the mid-1990s in response to climate variability.
Resumo:
The ecological effects of invasive species depend on myriad environmental contexts, rendering understanding problematic. Functional responses provide a means to quantify resource use by consumers over short timescales and could therefore provide insight into how the effects of invasive species vary over space and time. Here, we use novel in situ microcosm experiments to track changes in the functional responses of two aquatic mesopredators, one native and the other an invader, as they undergo diel vertical migrations through a lake water column.
The Ponto–Caspian mysid, Hemimysis anomala, a known ecologically damaging invader, generally had higher a functional response towards cladoceran prey than did a native trophic analogue, Mysis salemaai. However, this differential was spatiotemporally dependent, being minimal during the day on the lake bottom, and increasing at night, particularly inshore.
Because the functional response of the native predator was spatiotemporally consistent, the above pattern was driven by changes in the invader functional response over the diel cycle. In particular, the functional response of H. anomala was significantly reduced on the lake bottom during the daytime relative to night, and predation was especially pronounced in shallow surface waters.
We demonstrate the context dependency of the effects of an invasive predator on prey populations and emphasise the utility of functional responses as tools to inform our understanding of predator–prey interactions. In situ manipulations integrate experimental rigour with field relevance and have the potential to reveal how impacts manifest over a range of spatiotemporal scales.
Resumo:
Much recent scholarship has been critical of the concept of a Dál Riatic migration to, or colonisation of, Argyll. Scepticism of the accuracy of the early medieval accounts of this population movement, arguing that these are late amendments to early sources, coupled with an apparent lack of archaeological evidence for such a migration have led to its rejection. It is argued here, however, that this rejection has been based on too narrow a reading of historical sources and that there are several early accounts which, while differing in detail, agree on one point of substance, that the origin of Scottish Dál Riata lies in Ireland. Also, the use of archaeological evidence to suggest no migration to Argyll by the Dál Riata is flawed, misunderstanding the nature of early migrations and how they might be archaeologically identified, and it's proposed that there is actually quite a lot of evidence for migration to Argyll by the Dál Riata, in the form of settlement and artefactural evidence, but that it is to be found in Ireland through the mechanism of counterstream migration, rather than in Scotland.
Resumo:
Human settlement of Oceania marked the culmination of a global colonization process that began when humans first left Africa at least 90,000 years ago. The precise origins and dispersal routes of the Austronesian peoples and the associated Lapita culture remain contentious, and numerous disparate models of dispersal (based primarily on linguistic, genetic, and archeological data) have been proposed. Here, through the use of mtDNA from 781 modern and ancient Sus specimens, we provide evidence for an early human-mediated translocation of the Sulawesi warty pig (Sus celebensis) to Flores and Timor and two later separate human-mediated dispersals of domestic pig (Sus scrofa) through Island Southeast Asia into Oceania. Of the later dispersal routes, one is unequivocally associated with the Neolithic (Lapita) and later Polynesian migrations and links modern and archeological Javan, Sumatran, Wallacean, and Oceanic pigs with mainland Southeast Asian S. scrofa. Archeological and genetic evidence shows these pigs were certainly introduced to islands east of the Wallace Line, including New Guinea, and that so-called "wild" pigs within this region are most likely feral descendants of domestic pigs introduced by early agriculturalists. The other later pig dispersal links mainland East Asian pigs to western Micronesia, Taiwan, and the Philippines. These results provide important data with which to test current models for human dispersal in the region. © 2007 by The National Academy of Sciences of the USA.
Resumo:
Lumpfish (Cyclopterus lumpus L. 1758) are widely distributed on both sides of the North Atlantic. They are a commercially important species, but stock size estimates have declined since the mid-1980s in Canada, Norway and Iceland. Little is known about the biology of this species, in particular the breeding migrations and population structure which are fundamental for effective management. This paper describes the development and characterization of twenty-two polymorphic microsatellite loci using next generation sequencing. The number of alleles per locus ranged from 3 to 27 in two geographically distant North Atlantic populations, with observed and expected heterozygosities ranging between 0. 0625-0. 979 and 0. 0618-0. 946, respectively. These loci are an important resource that will allow assessment of the population genetic structure of this species, and contribute to its appropriate management.
Resumo:
The Neolithic and Bronze Age transitions were profound cultural shifts catalyzed in parts of Europe by migrations, first of early farmers from the Near East and then Bronze Age herders from the Pontic Steppe. However, a decades-long, unresolved controversy is whether population change or cultural adoption occurred at the Atlantic edge, within the British Isles. We address this issue by using the first whole genome data from prehistoric Irish individuals. A Neolithic woman (3343–3020 cal BC) from a megalithic burial (10.3× coverage) possessed a genome of predominantly Near Eastern origin. She had some hunter–gatherer ancestry but belonged to a population of large effective size, suggesting a substantial influx of early farmers to the island. Three Bronze Age individuals from Rathlin Island (2026–1534 cal BC), including one high coverage (10.5×) genome, showed substantial Steppe genetic heritage indicating that the European population upheavals of the third millennium manifested all of the way from southern Siberia to the western ocean. This turnover invites the possibility of accompanying introduction of Indo-European, perhaps early Celtic, language. Irish Bronze Age haplotypic similarity is strongest within modern Irish, Scottish, and Welsh populations, and several important genetic variants that today show maximal or very high frequencies in Ireland appear at this horizon. These include those coding for lactase persistence, blue eye color, Y chromosome R1b haplotypes, and the hemochromatosis C282Y allele; to our knowledge, the first detection of a known Mendelian disease variant in prehistory. These findings together suggest the establishment of central attributes of the Irish genome 4,000 y ago.