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Journal articles on the topic 'Migratory connections'
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Veen, Thor. "Unravelling migratory connections: the next level." Molecular Ecology 22, no. 16 (2013): 4144–46. http://dx.doi.org/10.1111/mec.12441.
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Pombo, Pedro. "Weaving Networks: the Economic Decline of Diu and Indian Ocean Circulations of the Vanza Weavers." Asian Review of World Histories 8, no. 1 (2020): 103–27. http://dx.doi.org/10.1163/22879811-12340066.
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Abstract Diu, on the Western India coast and Portuguese territory until 1961, was a strategic port connecting the subcontinent with Eastern Africa until the industrial mills in Western India provoked the decline of the traditional textile production systems in Gujarat and the near erasure of the maritime trade in Diu. Sustained by ethnographic and archival research, this article shows how the decline of maritime trading from Diu exposed the lack of Portuguese control over the trading routes connecting Asia and Africa. Local communities responded to changing contexts by developing new migratory connections with Mozambique. Among them are the Diuese weavers’ community, the Vanza, whose role in Mozambican trade, and later postcolonial connections with European countries, is still mostly to be examined. Though a preliminary observation of their migratory initiatives we observe how lives across the Indian Ocean navigated relatively apart from colonial intentions, pursuing their own winds and tides.
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Warren, Victoria E., Rochelle Constantine, Michael Noad, Claire Garrigue, and Ellen C. Garland. "Migratory insights from singing humpback whales recorded around central New Zealand." Royal Society Open Science 7, no. 11 (2020): 201084. http://dx.doi.org/10.1098/rsos.201084.
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The migration routes of wide-ranging species can be difficult to study, particularly at sea. In the western South Pacific, migratory routes of humpback whales between breeding and feeding areas are unclear. Male humpback whales sing a population-specific song, which can be used to match singers on migration to a breeding population. To investigate migratory routes and breeding area connections, passive acoustic recorders were deployed in the central New Zealand migratory corridor (2016); recorded humpback whale song was compared to song from the closest breeding populations of East Australia and New Caledonia (2015–2017). Singing northbound whales migrated past New Zealand from June to August via the east coast of the South Island and Cook Strait. Few song detections were made along the east coast of the North Island. New Zealand song matched New Caledonia song, suggesting a migratory destination, but connectivity to East Australia could not be ruled out. Two song types were present in New Zealand, illustrating the potential for easterly song transmission from East Australia to New Caledonia in this shared migratory corridor. This study enhances our understanding of western South Pacific humpback whale breeding population connectivity, and provides novel insights into the dynamic transmission of song culture.
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Modesti, Camilla, Alessandra Talamo, Annamaria Recupero, and Giampaolo Nicolais. "Connections: The Use Social Associations With Migratory Background Make of ICT to Build Social Capital for Newcomers’ Social Integration." American Behavioral Scientist 64, no. 13 (2020): 1889–905. http://dx.doi.org/10.1177/0002764220952132.
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Psychological studies in the field of migration attest that social integration is enhanced by social capital. Communities of origin and the ones of resettlement play different role in the promotion of newcomers’ social integration. Nevertheless, researches highlighted that connections between migrants and resettlement communities are the hardest to be established. By reinforcing existing ties and generating new connections among communities, information and communication technologies (ICT) represent a resource for the creation of migrants’ social capital. The article presents two case studies addressing the use that a refugee- and a migrant-led association make of ICT to develop social capital aimed at fostering newcomers’ social integration. An ethnographic approach was adopted, and qualitative data have been collected. Results show that in the associations ICT are aimed at easing connections within migrants and between migrants and the resettlement community by directly fostering the establishment of social ties and by spreading positive narratives about migration. Through the empowerment of refugees and migrants, ICT emerge as tools that lay the foundations for the promotion of social cohesion.
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Scheibelhofer, Elisabeth. "Potential of qualitative network analysis in migration studies- Reflections based on an empirical analysis of young researchers’ mobility aspirations." MIGRATION LETTERS 8, no. 2 (2014): 111–20. http://dx.doi.org/10.33182/ml.v8i2.159.
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Based on the example of an empirical research study, the paper examines the strengths and limitations of a qualitative network approach to migration and mobility. The method of graphic drawings produced by the respondents within an interview setting was applied. With this method, we argue to be able to analyse migrants’ specific social embeddedness and its influence on future mobility aspirations. Likewise, connections between the migratory biography and the individuals’ various social relations are investigated.
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Pizarro, J. Cristobal, and Brendon M. H. Larson. "Feathered Roots and Migratory Routes: Immigrants and Birds in the Anthropocene." Nature and Culture 12, no. 3 (2017): 189–218. http://dx.doi.org/10.3167/nc.2017.120301.
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Human mobility necessitates that people adapt not only to a new society but also to a new natural environment and biodiversity. We use birds as biodiversity proxies to explore the place experiences of 26 Latin Americans adapting to Canada and the United States. Using interviews with open-ended questions, we prompted participants to identify birds that were linked to remarkable experiences in both places of origin and immigration, which we coded respectively as “roots” and “routes.” Participants reported foundational keystone species linked to their cultural heritage and conspicuous key species they associated with self-realization in the new place. Linking species, involving connections between roots and routes, triggered a process of place recalibration in association with key and keystone birds that worked as points of reference. We suggest that biodiversity offers critical social functions that need to be addressed by social integration programs promoting conviviality between humans and nature in the Anthropocene.
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Sawant, Ketki, Yujun Chen, Nirupama Kotian, Kevin M. Preuss, and Jocelyn A. McDonald. "Rap1 GTPase promotes coordinated collective cell migration in vivo." Molecular Biology of the Cell 29, no. 22 (2018): 2656–73. http://dx.doi.org/10.1091/mbc.e17-12-0752.
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During development and in cancer, cells often move together in small to large collectives. To move as a unit, cells within collectives need to stay coupled together and coordinate their motility. How cell collectives remain interconnected and migratory, especially when moving through in vivo environments, is not well understood. The genetically tractable border cell group undergoes a highly polarized and cohesive cluster-type migration in the Drosophila ovary. Here we report that the small GTPase Rap1, through activation by PDZ-GEF, regulates border cell collective migration. We find that Rap1 maintains cell contacts within the cluster, at least in part by promoting the organized distribution of E-cadherin at specific cell–cell junctions. Rap1 also restricts migratory protrusions to the front of the border cell cluster and promotes the extension of protrusions with normal dynamics. Further, Rap1 is required in the outer migratory border cells but not in the central nonmigratory polar cells. Such cell specificity correlates well with the spatial distribution of the inhibitory Rapgap1 protein, which is higher in polar cells than in border cells. We propose that precisely regulated Rap1 activity reinforces connections between cells and polarizes the cluster, thus facilitating the coordinated collective migration of border cells.
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Knotter, Ad. "Transnational Cigar-Makers: Cross-Border Labour Markets, Strikes, and Solidarity at the Time of the First International (1864–1873)." International Review of Social History 59, no. 3 (2014): 409–42. http://dx.doi.org/10.1017/s0020859014000443.
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AbstractSeveral authors have argued that one of the main goals of the International Working Men's Association was to control transnational labour markets. In the eyes of trade unionists, especially in Britain, uncontrolled cross-border migratory movements threatened to undermine wage standards and working conditions. Their solution was to organize internationally, both to prevent strike-breaking and wage-cutting by workers from abroad, and to support unions elsewhere to raise wage standards in their home countries. Cigar-makers operated on a cross-border labour market and were very prominent in the First International. In this article I describe the connections between the German, British, Dutch, Belgian, and American cigar-makers as migratory workers, and their actions to stimulate, support, and coordinate trade unions internationally. I argue that the international cooperation of cigar-makers was primarily motivated by a wish to regulate their cross-border labour market, not so much by an abstract ideal of international solidarity.
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van den Hoff, John, Clive R. McMahon, Graham R. Simpkins, Mark A. Hindell, Rachael Alderman, and Harry R. Burton. "Bottom-up regulation of a pole-ward migratory predator population." Proceedings of the Royal Society B: Biological Sciences 281, no. 1782 (2014): 20132842. http://dx.doi.org/10.1098/rspb.2013.2842.
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As the effects of regional climate change are most pronounced at polar latitudes, we might expect polar-ward migratory populations to respond as habitat suitability changes. The southern elephant seal ( Mirounga leonina L.) is a pole-ward migratory species whose populations have mostly stabilized or increased in the past decade, the one exception being the Macquarie Island population which has decreased continuously over the past 50 years. To explore probable causes of this anomalous trend, we counted breeding female seals annually between 1988 and 2011 in order to relate annual rates of population change ( r ) to foraging habitat changes that have known connections with atmospheric variability. We found r (i) varied annually from −0.016 to 0.021 over the study period, (ii) was most effected by anomalous atmospheric variability after a 3 year time lag was introduced ( R = 0.51) and (iii) was associated with sea-ice duration (SID) within the seals’ foraging range at the same temporal lag. Negative r years may be extrapolated to explain, at least partially, the overall trend in seal abundance at Macquarie Island; specifically, increasing SID within the seals foraging range has a negative influence on their abundance at the island. Evidence is accruing that suggests southern elephant seal populations may respond positively to a reduced sea-ice field.
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Blasko, J., K. Fabianova, M. Martoncikova, D. Sopkova, and E. Racekova. "Immunohistochemical Evidence for the Presence of Synaptic Connections of Nitrergic Neurons in the Rat Rostral Migratory Stream." Cellular and Molecular Neurobiology 33, no. 6 (2013): 753–57. http://dx.doi.org/10.1007/s10571-013-9956-1.
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Alves, Jorge Fernandes, and Maria José Moutinho Santos. "Emigração e rede familiar. Os Mello e Souza-de Abragão ao Brasil oitocentista." História: Revista da Faculdade de Letras da Universidade do Porto 11, no. 1 (2021): 153–72. http://dx.doi.org/10.21747/0871164x/hist11_1a7.
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The text starts from the concept of family network to frame the migratory movement and the installation of a male part of a large family from Abragão, Penafiel, in Brazil, following the previous migration of a cognate branch.In the middle of the19th century, we found several elements of the Mello e Sousa family establishedin the trade of Rio de Janeiro, with close connections at an early stage and later autonomous routes. We seek to follow the backing of these emigrants, signaling family support and commercial transactions on the most relevant individual life histories
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Darling, James D., and Daniel J. McSweeney. "Observations on the migrations of North Pacific humpback whales (Megaptera novaeangliae)." Canadian Journal of Zoology 63, no. 2 (1985): 308–14. http://dx.doi.org/10.1139/z85-047.
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Migratory destinations of northeast Pacific humpback whales (Megaptera novaeangliae) were determined by repeat sightings of photographically identified individuals, using the black and white pigment patterns on the ventral side of the flukes. Individuals identified between 1975 and 1982 included 1056 in Hawaii, 420 in southeast Alaska, 54 in Prince William Sound, Alaska, 8 in British Columbia, and 12 in the Revillagigedo Islands, Mexico. Of these, 51 were found in Hawaii and southeast Alaska, 8 in Hawaii and Prince William Sound, 1 in Hawaii and British Columbia, and 1 in Mexico and Hawaii. Some travelled for four, five, and six successive seasons between Hawaii and southeast Alaska. One whale was found in British Columbia one summer and in southeast Alaska the next; the same individuals were commonly found off both Kona, Hawaii, and West Maui in winter. The study suggests that separate summer feeding areas may exist in the northeast Pacific where individuals prefer to feed. Migratory connections suggest that all humpbacks in the eastern North Pacific are of the same stock.
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Agostinho, Angelo Antônio, Elineide Eugênio Marques, Carlos Sérgio Agostinho, Deusimar Augusto de Almeida, Rafael José de Oliveira, and Jussiclene Rodrigues Bezerra de Melo. "Fish ladder of Lajeado Dam: migrations on one-way routes?" Neotropical Ichthyology 5, no. 2 (2007): 121–30. http://dx.doi.org/10.1590/s1679-62252007000200005.
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Fish ladders are generally conceived to reestablish connectivity among critical habitats for migratory species, thus mitigating the impacts of the blockage of migration routes by dams. If this management tool is to be meaningful for conserving fish species, it must provide a fully permeable connection and assure both upward and downward movements. However, because reservoirs have very different hydrodynamics than the original river, it is expected that, at least in the inner area, they may constitute an additional barrier to this movement, especially for descending fish. Thus, the present study sought to determine if migratory fish and their offspring disperse downstream from the dam after ascending a ladder and spawning in the upper reaches of a basin. To achieve this purpose, we evaluated the limitation imposed by lentic areas to the descent of eggs, larvae and adults of migratory species; we also determined the abundance and composition of larvae present in the plankton near the dam, and compared the intensity of the upward and downward movements of adult fish. Samples of ichthyoplankton were taken upriver, inside the reservoir, in the river downstream from the dam, and in the forebay of the Lajeado Dam on the Tocantins River (Luis Eduardo Magalhães Hydroelectric Plant), from October, 1999 through September, 2004. The densities of fish ascending and descending the ladder were determined experimentally on eight occasions, from June, 2004 to March, 2005. Due to difficulties in identifying the true fish origin (up or down) in the environments connected by the fish passage system, the evaluation of the distribution of migratory fish in reservoirs was based on the landings of the commercial fishery conducted along the Itaipu Reservoir during the four years preceding (2001 through 2003) the construction of the lateral channel (fish-passage mechanism). Fish eggs and larvae drifting down the Tocantins River did not appear in samples taken in the lower half of the reservoir; those found in water flowing through the spillways, turbines or fish ladder of Lajeado Dam belonged essentially to non-migratory clupeids that spawn in the inner part of the reservoir. In addition, results showed that in a reservoir with no fish-passage mechanism, migrants select habitats that still maintain riverine characteristics, in the upper parts of the impounded area. The downward movements are negligible compared to those upward, in the experiments conducted in the fish ladder. It is concluded, therefore, that the Lajeado fish ladder, and possibly those at other dams, is essentially a one-way route that promotes upstream movements of migrants, without the necessary return of adults or their offspring. Thus, the low permeability of the connections provided by these management tools can drastically increase the level of environmental impact that they were actually intended to reduce.
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BOWONG, SAMUEL, JEAN JULES TEWA, and JURGEN KURTHS. "DYNAMICS OF THE SPREAD OF TUBERCULOSIS IN HETEROGENEOUS COMPLEX METAPOPULATIONS." International Journal of Bifurcation and Chaos 23, no. 07 (2013): 1350128. http://dx.doi.org/10.1142/s0218127413501289.
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This paper analyzes the dynamics of the spread of tuberculosis (TB) on complex metapopulation, that is, networks of populations connected by migratory flows whose configurations are described in terms of connectivity distribution of nodes (patches) and the conditional probabilities of connections among classes of nodes sharing the same degree. The migration and transmission processes occur simultaneously. For uncorrelated networks, we give a necessary and sufficient condition for the instability of the disease-free equilibrium. The existence of endemic equilibria is also discussed. Finally, the prevalence of the TB infection across the metapopulation as a function of the path connectivity is studied using numerical simulations.
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Bălan, Mariana, and Svitlana Bilan. "Recent Dimensions of Regional Migration." Journal of Intercultural Management 12, no. 4 (2020): 91–105. http://dx.doi.org/10.2478/joim-2020-0053.
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Abstract Objective: The purpose of this article is to make an analysis of the size and structure of migratory flows at regional and sub-regional level. Methodology: Descriptive statistical analysis was mainly used to visualize and synthesize information about the evolution of the structure and size of migratory flows in major regions of the world. Findings: The importance of contemporary migration is related not only to the number of migrants, but also to the fact that the migratory phenomenon has become global and takes on more and more diverse forms. People travel for various periods of time, but shorter. They adopt a pattern of circulatory migration, continue to maintain strong connections with where they left from or practice unregulated migration. Migration has become a defining feature of the modern global economy, and the main factors underlying its expansion are the processes of globalization, technical progress, the new economic order, etc. In 2019, the number of l migrants at world level reached 271.6 million, well above the values forecast by international bodies in recent years. In the last three decades, more developed regions have received 69 million international migrants, while less developed regions have received only 50 million. The highest migratory flows were recorded in high-income countries (98 million persons), and middle and low-income countries added only about 20 million persons to migrants’ stock (17 million and 3 million, respectively). Value Added: The paper presents an analysis of the size and structure of migratory flows at the regional level, providing a more detailed picture of migration, and presenting a different but complementary perspective of migrants and movements from different parts of the world. A comparative analysis of migrant flows at regional level and on large migration corridors is performed, but also of the structure by age groups and gender of regional migrants. Recommendations: The analysis of data on regional migration shows significant differences in migration patterns between regions. Greater recognition of regional migration patterns, variations and complexities can help shape strategic and sustainable responses of the migration policies. It is also necessary to pay attention to the regional dimensions and variations of international migration that may have critical implications for debates and regulations, especially (but not only) globally.
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Casillas, Rodolfo. "Migración internacional y cambio climático: conexiones y desconexiones entre México y Centroamérica/ International Migration and Climate Change: Connections and Disconnections between Mexico and Central America." URVIO. Revista Latinoamericana de Estudios de Seguridad, no. 26 (February 10, 2020): 73–92. http://dx.doi.org/10.17141/urvio.26.2020.4038.
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El cambio climático en Centroamérica genera, entre otros efectos, migraciones en el interior o al exterior de los países de origen. La migración centroamericana que transita por México es importante por su volumen, por ser indocumentada y por su diversificación social, de género y etaria. Algunas localidades mexicanas susceptibles al cambio climático están en las rutas migratorias que atraviesan el país, mientras que otras con la misma susceptibilidad posiblemente sean receptoras de emergentes asentamientos indefinidos de quienes desde 2019 esperan respuesta a su solicitud de refugio en Estados Unidos. El objetivo de este artículo es analizar la posible relación entre las localidades mexicanas con problemas climáticos y el tránsito de migraciones centroamericanas, así como referir los riesgos de aquellas que sean receptoras de los nuevos asentamientos. Con base en fuentes documentales y hemerográficas y resultados empíricos, se analizan esos procesos desde una perspectiva histórico- procesual. Las conclusiones apuntan a vacíos de conocimiento; flujos migratorios mixtos, que incluyen a migrantes por razones climáticas; a tránsito por un bajo número de localidades mexicanas con riesgo climático, dispersas por las rutas migratorias; a procesos con algunas conexiones y a otros que, sin tenerlas, no escapan al riesgo de potenciar posibles intolerancias sociales.
 
 Abstract
 Climate change in Central America generates, among other effects, migrations inside and outside the countries of origin. The Central American migration that travels through Mexico is important because of its volume, because it is undocumented and diversified socially, by gender and age. Some Mexican localities susceptible to climate change are on the migratory routes through Mexico, while others with the same susceptibility may be receivers of emerging indefinite settlements from those who expect a response to their request for refuge in the United States, since 2019. The objective of this article is to analyze the possible relationship between the Mexican localities with climatic problems and the transit of Central American migrations, as well as referring the risks of those who are receivers of the new settlements. Based on secondary sources and empirical results, these processes are analyzed from a procedural historical perspective. The conclusions point to knowledge gaps, mixed migratory flows that include migrants for climatic reasons, transit through a low number of Mexican towns with climate risk, dispersed by migratory routes and also to processes with some connections and others that, without having them, do not escape the risk of fostering possible social intolerances.
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Introini, Fabio. "Tra media e socialitŕ. I consumi culturali nelle sfere relazionali." IKON, no. 56 (November 2009): 75–107. http://dx.doi.org/10.3280/ikr2008-056004.
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- Sociologists of migration are paying increasing attention to the transnational aspects of migratory phenomena. In particular, the term ‘transnationalism' refers mainly to the tight-knit network of exchanges and two-way connections that migrants create between their countries of origin and of destination. It also refers to the fact that often - but not always - these same migrants commit to, and simultaneously participate in, the social lives of their places of origin and of residence. This article analyzes how the first and second generation Egyptians and Peruvians, living in Milan, interact with the society in which they live and with the society they come from. Relations in which the role of communication and information media is almost always crucial.
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Caballero, Susana, Debbie Steel, Logan Pallin, et al. "Migratory connections among breeding grounds off the Eastern Pacific and feeding areas in the Antarctic Peninsula based on genotype matching." Boletín de Investigaciones Marinas y Costeras 50, SuplEsp (2021): 31–40. http://dx.doi.org/10.25268/bimc.invemar.2021.50.suplesp.933.
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We analysed 114 DNA samples collected in different locations within the stock G breeding grounds, including Ecuador and the northern and southern Pacific of Colombia. We genotyped 15 microsatellite loci, sexed all samples, and performed genotype comparisons. Genotype comparisons were done using a DNA register of previously genotyped individuals from the Colombian breeding ground and the Antarctic Peninsula feeding Area. We confirmed connectivity between feeding grounds in Antarctic Peninsula and breeding grounds in Colombia and Ecuador using microsatellite loci. We found recaptures within each sampling location in the same year, but we also found a few recaptures in the same locations between years both in breeding and feeding grounds. Interestingly, we found recaptures between breeding and feeding grounds using samples collected 20 years apart, providing some information about longevity in this stock. Further comparisons with other data sets (Brazil, North Pacific) are needed to understand the migratory connectivity of this stock.
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Constantine, Rochelle, Kirsty Russell, Nadine Gibbs, Simon Childerhouse, and C. Scott Baker. "PHOTO-IDENTIFICATION OF HUMPBACK WHALES (MEGAPTERA NOVAEANGLIAE) IN NEW ZEALAND WATERS AND THEIR MIGRATORY CONNECTIONS TO BREEDING GROUNDS OF OCEANIA." Marine Mammal Science 23, no. 3 (2007): 715–20. http://dx.doi.org/10.1111/j.1748-7692.2007.00124.x.
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Puelles, Luis. "Comments on the Updated Tetrapartite Pallium Model in the Mouse and Chick, Featuring a Homologous Claustro-Insular Complex." Brain, Behavior and Evolution 90, no. 2 (2017): 171–89. http://dx.doi.org/10.1159/000479782.
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This essay reviews step by step the conceptual changes of the updated tetrapartite pallium model from its tripartite and early tetrapartite antecedents. The crucial observations in mouse material are explained first in the context of assumptions, tentative interpretations, and literature data. Errors and the solutions offered to resolve them are made explicit. Next, attention is centered on the lateral pallium sector of the updated model, whose definition is novel in incorporating a claustro-insular complex distinct from both olfactory centers (ventral pallium) and the isocortex (dorsal pallium). The general validity of the model is postulated at least for tetrapods. Genoarchitectonic studies performed to check the presence of a claustro-insular field homolog in the avian brain are reviewed next. These studies have indeed revealed the existence of such a complex in the avian mesopallium (though stratified outside-in rather than inside-out as in mammals), and there are indications that the same pattern may be found in reptiles as well. Peculiar pallio-pallial tangential migratory phenomena are apparently shared as well between mice and chicks. The issue of whether the avian mesopallium has connections that are similar to the known connections of the mammalian claustro-insular complex is considered next. Accrued data are consistent with similar connections for the avian insula homolog, but they are judged to be insufficient to reach definitive conclusions about the avian claustrum. An aside discusses that conserved connections are not a necessary feature of field-homologous neural centers. Finally, the present scenario on the evolution of the pallium of sauropsids and mammals is briefly visited, as highlighted by the updated tetrapartite model and present results.
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Makrakis, Sergio, Ana P. S. Bertão, Jhony F. M. Silva, Maristela C. Makrakis, Fco Javier Sanz-Ronda, and Leandro F. Celestino. "Hydropower Development and Fishways: A Need for Connectivity in Rivers of the Upper Paraná Basin." Sustainability 11, no. 13 (2019): 3749. http://dx.doi.org/10.3390/su11133749.
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South American rivers have become intensely affected by the construction of hydroelectric dams that block the river’s connectivity for migratory fish species. In order to mitigate the problems caused by dams and to reestablish connections between habitats, fishways are implemented. Fishways are structures that aid fish in overcoming obstacles and help preserve migratory, reproductive, and feeding routes. This study performed an inventory of all hydropower plants—present and future—in the Upper Paraná River, with the objective of identifying fishways unknown to scientific literature, as well as the task of mapping them. By doing so, the current situation of structural connectivity via fishways in the Upper Paraná River Basin was described. Overall, 389 dams along 209 rivers were identified; of these, only 9% (35 dams) have fishways. In addition, an alarming explosion of future medium-sized hydropower plants was observed, with an expectation of an almost 500% increase in relation to those existing. This data reveals a trend of reduction of free-flowing river stretches, which are crucial habitats for Neotropical potamodromous species, and point to a deficiency in the structural connectivity of existing hydropower dams. Furthermore, if the implementations of these expected constructions are associated with limited connectivity as a result of the absence of fishways, the management of fisheries and their resources in the Upper Paraná River may become unsustainable.
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Zhang, Yamian, Yi Zhu, Aojie Zuo, Li Wen, and Guangchun Lei. "Numerical Response of Migratory Shorebirds to Prey Distribution in a Large Temperate Arid Wetland, China." Scientifica 2016 (2016): 1–9. http://dx.doi.org/10.1155/2016/1297603.
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Wuliangsuhai Lake provides important breeding and stopover habitats for shorebirds. The health of this wetland ecosystem is rapidly deteriorating due to eutrophication and water pollution and environmental management is urgently needed. To explore the connections among ecosystem health, prey density, and shorebird populations, we conducted surveys of both the benthic macroinvertebrates and shorebirds in the shorebird habitat of the wetland during the 2011 autumn migration season. The abundance of both shorebirds and benthic macroinvertebrates varied significantly in both space and time. Our data showed a clear association between shorebird populations and the density of benthic macroinvertebrates, which explained 53.63% of the variation in shorebird abundance. The prey density was strongly affected by environmental factors, including water and sediment quality. Chironomidae were mainly found at sites with higher total phosphorus, but with lower sediment concentrations of Cu. Lymnaeidae were mainly found at sites with a higher pH, lower salinity, and lower concentrations of total phosphorus and Cu. Habitats with very high concentrations of total phosphorus, heavy metals, or salinity were not suitable for benthic macroinvertebrates. Our findings suggest that the reductions of nutrient and heavy metal loadings are crucial in maintaining the ecological function of Wuliangsuhai as a stopover habitat for migratory shorebirds.
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Force, Pierre. "Eighteenth-Century Matrimonial Strategies and Emigration to the Americas: The House of Berrio in La Bastide Clairence." Annales (English ed.) 68, no. 01 (2013): 75–106. http://dx.doi.org/10.1017/s2398568200000327.
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Prior to the massive wave of emigration to South America during the nineteenth century, inhabitants of rural communities in the western French Pyrenees emigrated in large numbers to Saint-Domingue and other Caribbean islands. This article examines the connections between migratory movements and the organization of these communities into “house societies” (Lévi-Strauss) in which the continuation of the “house” was paramount and no new “houses” could be founded. Adopting a microhistorical approach, it analyzes the complex role of inheritance rights in the decision to emigrate and reconstructs the networks that made emigration possible. Unlike the traditional belief that sons were forced to leave because they were deprived of their share of inheritance, the family unit fully supported the emigration of its younger members. This article also argues that emigration simultaneously resulted from and undermined the “house system.”
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Hobson, Keith A., and Franz Bairlein. "Isotopic fractionation and turnover in captive Garden Warblers (Sylvia borin): implications for delineating dietary and migratory associations in wild passerines." Canadian Journal of Zoology 81, no. 9 (2003): 1630–35. http://dx.doi.org/10.1139/z03-140.
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There is currently a great deal of interest in using stable-isotope methods to investigate diet and migratory connections in wild passerines. To apply these methods successfully, it is important to understand how stable isotopes discriminate or change between diet and the tissue of interest and what the element-turnover rates are in metabolically active tissues. Of particular use are studies that sample birds non-destructively through the use of blood and feathers. We investigated patterns of isotopic discrimination between diet and blood and feathers of Garden Warblers (Sylvia borin) raised on an isotopically homogeneous diet (48% C, 5% N) and then switched to one of two experimental diets, mealworms (56.8% C, 8.3% N) and elderberries, Sambucus niger (47.4% C, 1.5% N). We established that the discrimination factors between diet and blood appropriate for stable carbon (δ13C) and nitrogen (δ15N) isotopes are +1.7‰ and +2.4‰, respectively. For feathers, these values were +2.7‰ and +4‰, respectively. Turnover of elemental nitrogen in whole blood was best approximated by an exponential-decay model with a half-life of 11.0 ± 0.8 days (mean ± SD). Corresponding turnover of carbon was estimated to range from 5.0 ± 0.7 to 5.7 ± 0.8 days. We conclude that this decoupling of nitrogen- and carbon-turnover rates can be explained by differences in metabolic routing of dietary macromolecules. Our results suggest that tracking frugivory in migratory passerines that switch diets between insects and fruits may be complicated if only a trophic-level estimate is made using δ15N measurements.
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Steel, D., M. Anderson, C. Garrigue, et al. "Migratory interchange of humpback whales (Megaptera novaeangliae) among breeding grounds of Oceania and connections to Antarctic feeding areas based on genotype matching." Polar Biology 41, no. 4 (2017): 653–62. http://dx.doi.org/10.1007/s00300-017-2226-9.
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Zueck González, Silvia Leticia. "De Brez, Trento al mineral de Sierra Mojada, Coahuila, México. Redes transnacionales de mineros italianos." Frontera norte 31 (January 1, 2019): 1–24. http://dx.doi.org/10.33679/rfn.v1i1.2033.
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This paper examines the migration flow of a community of farmers from Brez, Trentino – at the time part of the Austro-Hungarian Empire – that headed to Sierra Mojada in Coahuila to work as miners. It describes the political and cultural characteristics of the receiving country, the Italian settlers, and the transnational geographic spaces they had to cross. Numerically the miners are only a small fraction of the total emigration from northern Italy to Mexico, yet the microhistorical Italian perspective makes it possible to frame them within international migratory movements. The study found consistent connections between migrants’ city of origin and adopted city, and identified the importance of networks of family members and friends for support for subsequent migration flows. Those who returned as a result of World War I – as subjects of the Kingdom of Italy – continued to work as miners in different locations, making them difficult to trace.
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Pao, Angela. "What Are You Reading?" Theatre Survey 47, no. 1 (2006): 107–9. http://dx.doi.org/10.1017/s0040557406000081.
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In one way or another, most of my recent readings have focused on diasporic and ethnic-minority literatures, experiences, and performances. From the late spring through midsummer, the readings I did in the context of a migratory experience in Europe produced new perspectives on questions of displacement, marginalization, and cross-cultural connections. I was invited to teach a graduate course on a departmental exchange with the Comparative Literature program of the University of Lisbon, and I designed a course called “Crossing Continents: Multiethnic Literatures of Europe and North America.” The course, taught in spring 2005, focused on understanding ways in which the critical paradigms used by literary and cultural critics in the United States might be extended profitably to the examination of immigrant and racial-minority cultures in Western Europe, and how diasporic and postcolonial models of migration developed by European scholars could expand the dimensions of U.S. ethnic studies.
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Casas-Agustench, Patricia, Albert Salas-Huetos, and Jordi Salas-Salvadó. "Mediterranean nuts: origins, ancient medicinal benefits and symbolism." Public Health Nutrition 14, no. 12A (2011): 2296–301. http://dx.doi.org/10.1017/s1368980011002540.
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AbstractObjectiveTo consider historical aspects of nuts in relation to origin and distribution, attributed medicinal benefits, symbolism, legends and superstitions.DesignReview of historical aspects of nuts.SettingMediterranean region.SubjectsThe varieties reviewed include almonds, walnuts, hazelnuts, pine nuts and pistachios.Results and conclusionsLike other foods, nuts have a wide variety of cultural connections to the areas where they grow and to the people who live there or eat them. History, symbolism and legends reveal the ancient tradition of nuts and how they are related to the lives of our ancestors. Archaeological excavations in eastern Turkey have uncovered the existence of a non-migratory society whose economy centred on harvesting nuts. This shows that nuts have been a staple in the human diet since the beginnings of history. Moreover, since ancient times nuts have been used for their medicinal properties. They also play a role in many old legends and traditions.
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Yeakel, Justin D., Jean P. Gibert, Thilo Gross, Peter A. H. Westley, and Jonathan W. Moore. "Eco-evolutionary dynamics, density-dependent dispersal and collective behaviour: implications for salmon metapopulation robustness." Philosophical Transactions of the Royal Society B: Biological Sciences 373, no. 1746 (2018): 20170018. http://dx.doi.org/10.1098/rstb.2017.0018.
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The spatial dispersal of individuals plays an important role in the dynamics of populations, and is central to metapopulation theory. Dispersal provides connections within metapopulations, promoting demographic and evolutionary rescue, but may also introduce maladapted individuals, potentially lowering the fitness of recipient populations through introgression of heritable traits. To explore this dual nature of dispersal, we modify a well-established eco-evolutionary model of two locally adapted populations and their associated mean trait values, to examine recruiting salmon populations that are connected by density-dependent dispersal, consistent with collective migratory behaviour that promotes navigation. When the strength of collective behaviour is weak such that straying is effectively constant, we show that a low level of straying is associated with the highest gains in metapopulation robustness and that high straying serves to erode robustness. Moreover, we find that as the strength of collective behaviour increases, metapopulation robustness is enhanced, but this relationship depends on the rate at which individuals stray. Specifically, strong collective behaviour increases the presence of hidden low-density basins of attraction, which may serve to trap disturbed populations, and this is exacerbated by increased habitat heterogeneity. Taken as a whole, our findings suggest that density-dependent straying and collective migratory behaviour may help metapopulations, such as in salmon, thrive in dynamic landscapes. Given the pervasive eco-evolutionary impacts of dispersal on metapopulations, these findings have important ramifications for the conservation of salmon metapopulations facing both natural and anthropogenic contemporary disturbances. This article is part of the theme issue ‘Collective movement ecology’.
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Huang, Yanyan, Michelle Wille, Ashley Dobbin, et al. "A 4-year study of avian influenza virus prevalence and subtype diversity in ducks of Newfoundland, Canada." Canadian Journal of Microbiology 59, no. 10 (2013): 701–8. http://dx.doi.org/10.1139/cjm-2013-0507.
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The island of Newfoundland, Canada, is at the eastern edge of North America and has migratory bird connections with the continental mainland as well as across the North Atlantic Ocean. Here, we report a 4-year avian influenza virus (AIV) epidemiological study in ducks in the St. John’s region of Newfoundland. The overall prevalence of AIV detection in ducks during this study was 7.2%, with American Black Ducks contributing the vast majority of the collected samples and the AIV positives. The juvenile ducks showed a significantly higher AIV detection rate (10.6%) compared with adults (3.4%). Seasonally, AIV prevalence rates were higher in the autumn (8.4%), but positives were still detected in the winter (4.6%). Preliminary serology tests showed a high incidence of previous AIV infection (20/38, 52.6%). A total of 43 viruses were characterized for their HA–NA or HA subtypes, which revealed a large diversity of AIV subtypes and little recurrence of subtypes from year to year. Investigation of the movement patterns of ducks in this region showed that it is a largely non-migratory duck population, which may contribute to the observed pattern of high AIV subtype turnover. Phylogenetic analysis of 4 H1N1 and one H5N4 AIVs showed these viruses were highly similar to other low pathogenic AIV sequences from waterfowl in North America and assigned all gene segments into American-avian clades. Notably, the H1N1 viruses, which were identified in consecutive years, possessed homologous genomes. Such detection of homologous AIV genomes across years is rare, but indicates the role of the environmental reservoir in viral perpetuation.
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Garrigue, C., S. Derville, C. Bonneville, et al. "Searching for humpback whales in a historical whaling hotspot of the Coral Sea, South Pacific." Endangered Species Research 42 (June 4, 2020): 67–82. http://dx.doi.org/10.3354/esr01038.
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Humpback whales Megaptera novaeangliae were severely depleted by commercial whaling. Understanding key factors in their recovery is a crucial step for their conservation worldwide. In Oceania, the Chesterfield-Bellona archipelago was a primary whaling site in the 19th century, yet has been left almost unaffected by anthropogenic activities since. We present the results of the first multidisciplinary dedicated surveys in the archipelago assessing humpback whale populations 2 centuries post-whaling. We encountered 57 groups during 24 survey days (2016-2017), among which 35 whales were identified using photographs of natural markings (photo-ID), 38 using genotyping and 22 using both. Humpback whales were sparsely distributed (0.041 whales km-1): most sightings concentrated in shallow inner-reef waters and neighbouring offshore shallow banks. The recently created marine protected area covers most of the areas of high predicted habitat suitability and high residence time from satellite-tracked whales. Surprisingly for a breeding area, sex ratios skewed towards females (1:2.4), and 45% of females were with calf. Connectivity was established with the New Caledonia breeding area to the east (mtDNA FST = 0.001, p > 0.05, 12 photo-ID and 10 genotype matches) and with the Australian Great Barrier Reef breeding area to the west (mtDNA FST = 0.006, p > 0.05). Movement of satellite-tracked whales and photo-ID matches also suggest connections with the east Australian migratory corridor. This study confirms that humpback whales still inhabit the Chesterfield-Bellona archipelago 2 centuries post whaling, and that this pristine area potentially plays a role in facilitating migratory interchange among breeding grounds of the western South Pacific.
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MANFREDINI, MATTEO, and MARCO BRESCHI. "Living alone in nineteenth-century rural Italy: was there any way out?" Continuity and Change 32, no. 3 (2017): 411–35. http://dx.doi.org/10.1017/s0268416017000327.
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AbstractFew studies have dealt with the issue of people living alone in pretransitional rural populations. Alone by choice or circumstances, usually poor and sometimes stigmatised, solitaries often had a hard life. This article analyses the characteristics and life-histories of people living alone in two rural villages in nineteenth-century Italy with the aim of understanding whether and how solitaries managed to find a way out from solitude. The results show that solitaries got married, joined another household, and especially emigrated more than the rest of the population, which is a strong indication of their willingness to break out of solitariness. The individuation of the demographic profile associated with such specific behaviours, namely being male, young, and widowed, allowed us also to draw some hypotheses on the role of availability and quality of social connections on the chances to escape from a solitary condition, as well as on the characteristics of migratory flows of solitaries from the countryside to the cities.
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Kalter, Frank, and Gisela Will. "Social Capital in Polish-German Migration Decision-Making." ANNALS of the American Academy of Political and Social Science 666, no. 1 (2016): 46–63. http://dx.doi.org/10.1177/0002716216643506.
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In this article we use a combination of retrospective and prospective data from the Polish Migration Project to examine the effect of social capital on the likelihood of migrating to Germany. We derive hypotheses from social capital theory about how personal connections to people with migratory experience affect the probability of migration, and we specify models to be estimated using both the retrospective and prospective data. Estimates of retrospective event history models confirm prior findings about social capital’s influence on migration decisions, and these findings are also generally confirmed using prospective data, even when potentially confounding variables are controlled. The prospective data also enable estimation of a two-stage decision model in which people first come to consider migration as an option and then rationally consider whether to depart. The estimates suggest that weak social ties are especially influential in predicting whether migration is considered, while strong ties are important in the decision to move.
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Vion, Anne-Clémence, Silvanus Alt, Alexandra Klaus-Bergmann, et al. "Primary cilia sensitize endothelial cells to BMP and prevent excessive vascular regression." Journal of Cell Biology 217, no. 5 (2018): 1651–65. http://dx.doi.org/10.1083/jcb.201706151.
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Blood flow shapes vascular networks by orchestrating endothelial cell behavior and function. How endothelial cells read and interpret flow-derived signals is poorly understood. Here, we show that endothelial cells in the developing mouse retina form and use luminal primary cilia to stabilize vessel connections selectively in parts of the remodeling vascular plexus experiencing low and intermediate shear stress. Inducible genetic deletion of the essential cilia component intraflagellar transport protein 88 (IFT88) in endothelial cells caused premature and random vessel regression without affecting proliferation, cell cycle progression, or apoptosis. IFT88 mutant cells lacking primary cilia displayed reduced polarization against blood flow, selectively at low and intermediate flow levels, and have a stronger migratory behavior. Molecularly, we identify that primary cilia endow endothelial cells with strongly enhanced sensitivity to bone morphogenic protein 9 (BMP9), selectively under low flow. We propose that BMP9 signaling cooperates with the primary cilia at low flow to keep immature vessels open before high shear stress–mediated remodeling.
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Goff, Loretta. "The Hyphenated Persona: Aidan Quinn’s Irish-American Performances." Persona Studies 3, no. 1 (2017): 60–75. http://dx.doi.org/10.21153/ps2017vol3no1art646.
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This article examines the hyphenated Irish-American identity performed by actor Aidan Quinn across a number of his media appearances. Hyphenated identities are frequently used in our increasingly globalised, migratory world to consolidate two or more national identifications into a singular, new identity. However, the performances of such identities are often complicated by shifting levels of identification, in line with the concept of identity salience, which result in multiple, protean identity performances—from either side of the hyphen—drawn upon as needed. “Celebrity identities” as a construct forms an ideal category for a broader exploration of hyphenated identity performance, as their highly visible public identities most overtly demonstrate the continuous processes of (economically influenced) construction, performance and negotiation that comprise all identity formation. Aidan Quinn, who holds dual United States and Irish citizenship, has spent significant time living in each country, is vocal about his connection to both and is often framed accordingly in the media, makes an ideal case study for examining the nuances of Irish-American identity performance which are magnified as a result his stardom. By looking at how the actor frames (and is framed regarding) his national connections, I interrogate the intricacies of how his experiences in each country are combined in some instances and separated in others, and ultimately argue that the two sides of his hyphenated Irish-American persona are largely kept separate, resulting in multiple identity performances rather than forming a cohesive, singular performance.
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Krissman, Fred. "Sin Coyote Ni Patrón: Why the “Migrant Network” Fails to Explain International Migration." International Migration Review 39, no. 1 (2005): 4–44. http://dx.doi.org/10.1111/j.1747-7379.2005.tb00254.x.
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The “migrant network” concept cannot explain large-scale international migratory flows. This article goes beyond a critique of its ahistorical and post factum nature. First, I argue that restrictions on its composition and functions also render the migrant network unable to explain why such migratory flows continue or expand even further. Second, a review of five studies illustrates why this concept, the propositions on which it rests, the methods it employs, and the conclusions that it imparts must be reconsidered. Third, the network analysis literature, along with my research data from the Mexico-U.S. case, suggest an alternative approach. “International migration networks” include those from the labor-sending hometowns who are emphasized in migrant network studies, as well as a variety of other actors based in the militarized border zone and the labor-receiving regions. I conclude that accurate studies of migration must include the employers that demand new immigrant workers, as well as the labor smugglers and all other actors that respond to this demand. Immigration studies that fail to do so provide erroneous analyses which camouflage the activities of many network actors, and furnish an academic fig leaf behind which unintended, counterproductive, and even lethal public policies have been implemented. By and large, the effective units of migration were (and are) neither individuals nor households but sets of people linked by acquaintance, kinship, and work experience who somehow incorporated American destinations into the mobility alternatives they considered when they reached critical decision points in their individual or collective lives (Tilly, 1990:84, emphasis added). [Migrant n]etwork connections constitute a form of social capital that people can draw upon to gain access to foreign employment (Massey et al., 1993:448, emphasis added)
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Lemme Ribeiro, Clara. "Apontamentos sobre experiências contemporâneas femininas de migrações e trabalho/Notes on feminine contemporary experiences of migration and work." Geografares, no. 28 (April 25, 2019): 200–223. http://dx.doi.org/10.7147/geo28.24393.
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A feminização das migrações foi compreendida, nos últimos anos, como uma das principais tendências do século XXI. O objetivo deste artigo é investigar tal processo, dando relevância para as conexões possíveis de serem estabelecidas com o conjunto da reprodução social. Para isso, consideramos as trajetórias de mulheres bolivianas que se inseriram em oficinas de costura na cidade de São Paulo. As experiências femininas de migração podem ser compreendidas como conteúdo concreto da crise contemporânea de reprodução do capital que se desdobra, simultaneamente, em crise do trabalho e da reprodução.Palavras-chave: feminização das migrações, crise do trabalho, migração boliviana. ABSTRACTOver the last years, the feminization of migrations has been considered one of the main social trends of the 21st century. The present paper investigates this process, underlining possible connections with social reproduction as a whole, through the analysis of Bolivian female migration trajectories. Feminine migratory experiences can be understood as a concrete content of the contemporary crisis of capital reproduction that simultaneously unfolds as a crisis of labor and reproduction.Keywords: feminization of migrations, labor crisis, Bolivian migration.
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Bronner, Marianne E. "Migrating into Genomics with the Neural Crest." Advances in Biology 2014 (June 22, 2014): 1–8. http://dx.doi.org/10.1155/2014/264069.
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Neural crest cells are a fascinating embryonic cell type, unique to vertebrates, which arise within the central nervous system but emigrate soon after its formation and migrate to numerous and sometimes distant locations in the periphery. Following their migratory phase, they differentiate into diverse derivatives ranging from peripheral neurons and glia to skin melanocytes and craniofacial cartilage and bone. The molecular underpinnings underlying initial induction of prospective neural crest cells at the neural plate border to their migration and differentiation have been modeled in the form of a putative gene regulatory network. This review describes experiments performed in my laboratory in the past few years aimed to test and elaborate this gene regulatory network from both an embryonic and evolutionary perspective. The rapid advances in genomic technology in the last decade have greatly expanded our knowledge of important transcriptional inputs and epigenetic influences on neural crest development. The results reveal new players and new connections in the neural crest gene regulatory network and suggest that it has an ancient origin at the base of the vertebrate tree.
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Ilnicki, Dariusz. "Rural Areas as the Origin and Destination of Permanent Internal Migrations between 2002 and 2017 in Poland. A Local-Level Analysis (Nuts 5)." Quaestiones Geographicae 39, no. 2 (2020): 15–30. http://dx.doi.org/10.2478/quageo-2020-0015.
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AbstractThe main aim of the study is to identify the main streams of permanent migration and determine their reach. Special attention has been paid to rural areas (a rural commune, the rural area of an urban–rural commune) as the origin and destination of migration. The study has been conducted at the lowest level of territorial division in Poland (NUTS 5 – cities and communes). The analysed data cover the period between 2002 and 2017 and come from the online database Demografia GUS [Demography, Statistics Poland]. While presenting the volume and directions of migrations, the total and maximum values of migration have been considered. This approach allowed identifying the catchment areas as well as the areas of migratory attractiveness. These areas are highly similar in terms of their spatial extent. However, they differ significantly in terms of magnitude and reach of the main migration streams. Permanent internal migrations within rural areas are the least significant among all migration directions. One of their characteristics is the fact that they are short–distance migrations, occurring between neighbouring units. Permanent internal migrations appear to be a good indicator of urbanisation of suburban zones and the shaping of functional urban–rural–urban connections.
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Perzanowski, Kajetan, Katarzyna Pędziwiatr, Paulina Konieczna, and Jan Śmiełowski. "Proposed migration corridors for large mammals in the south-east of Polish Carpathians." Zoology and Ecology 30, no. 30 (2020): 63–72. http://dx.doi.org/10.35513/21658005.2020.1.9.
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The aim of the study was the delineation of migratory corridors migration for large mammals between the Ukrainian Carpathians and the western part of their range in Poland. Potential corridors for the wolf (Canis lupus), brown bear (Ursus arctos), lynx (Lynx lynx), wisent (Bison bonasus), red deer (Cervus elaphus), and wild boar (Sus scrofa) were identified within 534,818 ha with the ArcGIS Corridor Designer software. Corridors of regional importance (42,283 ha in total) and local connections between habitat patches (13,154 ha) were delineated separately according to the least-cost path criterion. We identified 115 critical points where heavy traffic, or the proximity of settlements, could obstruct animal movements. A considerable number of such critical points indicate the urgency for ensuring the functionality of the remaining linkage. The permeability of barriers between habitat patches was determined by ground observations, confirming the presence of target species. The highest proportion of patches estimated by experts as optimal and suboptimal was for wild boar (91%), while the lowest for lynx (52%). The proportion of habitats avoided or useless due to anthropogenic barriers was 34% for lynx, 25% for wisents, and 19% for brown bears.
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Landry, Michael R., Lynnath E. Beckley, and Barbara A. Muhling. "Climate sensitivities and uncertainties in food-web pathways supporting larval bluefin tuna in subtropical oligotrophic oceans." ICES Journal of Marine Science 76, no. 2 (2018): 359–69. http://dx.doi.org/10.1093/icesjms/fsy184.
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Abstract Compared with high-latitude seas, the ecological implications of climate change for top consumers in subtropical regions are poorly understood. One critical area of knowledge deficiency is the nature of food-web connections to larvae during their vulnerable time in the plankton. Bluefin tuna (BFT) are highly migratory temperate species whose early life stages are spent in ultra-oligotrophic subtropical waters. Dietary studies of BFT larvae provide evidence of prey-limited growth coupled with strong selection for specific prey types—cladocerans and poecilostomatoid copepods—whose paradoxical or poorly resolved trophic characteristics do not fit the conventional understanding of open-ocean food-web structure and flows. Current knowledge consequently leaves many uncertainties in climate change effects, including the possibility that increased nitrogen fixation by Trichodesmium spp. might enhance resiliency of BFT larvae, despite a projected overall decline in system productivity. To advance understanding and future predictions, the complementary perspectives of oceanographers and fisheries researchers need to come together in studies that focus on the trophic pathways most relevant to fish larvae, the factors that drive variability in spawning regions, and their effects on larval feeding, growth, and survival.
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Wilson, Robert E., Judy R. Gust, Margaret R. Petersen, and Sandra L. Talbot. "Spatial Genetic Structure of Long-tailed Ducks (Clangula hyemalis) among Alaskan, Canadian, and Russian Breeding Populations + Supplementary Appendix Tables S1 and S2 (See Article Tools)." ARCTIC 69, no. 1 (2016): 65. http://dx.doi.org/10.14430/arctic4548.
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<p class="Pa5" style="text-align: justify; text-justify: inter-ideograph;"><span style="font-size: 10.0pt; color: #221e1f;">Arctic ecosystems are changing at an unprecedented rate. How Arctic species are able to respond to such environmental change is partially dependent on the connections between local and broadly distributed populations. For species like the Long-tailed Duck (<em>Clangula hyemalis</em>), we have limited telemetry and band-recovery information from which to infer population structure and migratory connectivity; however, genetic analyses can offer additional insights. To examine population structure in the Long-tailed Duck, we characterized variation at mtDNA control region and microsatellite loci among four breeding areas in Alaska, Canada, and Russia. We observed significant differences in the variance of mtDNA haplotype frequencies between the Yukon-Kuskokwim Delta (YKD) and the three Arctic locations (Arctic Coastal Plain in Alaska, eastern Siberia, and central Canadian Arctic). However, like most sea duck genetic assessments, our study found no evidence of population structure based on autosomal microsatellite loci. Long-tailed Ducks use multiple wintering areas where pair formation occurs with some populations using both the Pacific and Atlantic Oceans. This situation provides a greater opportunity for admixture across breeding locales, which would likely homogenize the nuclear genome even in the presence of female philopatry. The observed mtDNA differentiation was largely due to the presence of two divergent clades: (A) a clade showing signs of admixture among all breeding locales and (B) a clade primarily composed of YKD samples. We hypothesize that the pattern of mtDNA differentiation reflects some degree of philopatry to the YKD and isolation of two refugial populations with subsequent expansion and admixture. We recommend additional genetic assessments throughout the circumpolar range of Long-tailed Ducks to further quantify aspects of genetic diversity and migratory connectivity in this species.</span></p>
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Malvaut, Sarah, and Armen Saghatelyan. "The Role of Adult-Born Neurons in the Constantly Changing Olfactory Bulb Network." Neural Plasticity 2016 (2016): 1–8. http://dx.doi.org/10.1155/2016/1614329.
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The adult mammalian brain is remarkably plastic and constantly undergoes structurofunctional modifications in response to environmental stimuli. In many regions plasticity is manifested by modifications in the efficacy of existing synaptic connections or synapse formation and elimination. In a few regions, however, plasticity is brought by the addition of new neurons that integrate into established neuronal networks. This type of neuronal plasticity is particularly prominent in the olfactory bulb (OB) where thousands of neuronal progenitors are produced on a daily basis in the subventricular zone (SVZ) and migrate along the rostral migratory stream (RMS) towards the OB. In the OB, these neuronal precursors differentiate into local interneurons, mature, and functionally integrate into the bulbar network by establishing output synapses with principal neurons. Despite continuous progress, it is still not well understood how normal functioning of the OB is preserved in the constantly remodelling bulbar network and what role adult-born neurons play in odor behaviour. In this review we will discuss different levels of morphofunctional plasticity effected by adult-born neurons and their functional role in the adult OB and also highlight the possibility that different subpopulations of adult-born cells may fulfill distinct functions in the OB neuronal network and odor behaviour.
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Manjunath, Yariswamy, David Porciani, Jonathan B. Mitchem, et al. "Tumor-Cell–Macrophage Fusion Cells as Liquid Biomarkers and Tumor Enhancers in Cancer." International Journal of Molecular Sciences 21, no. 5 (2020): 1872. http://dx.doi.org/10.3390/ijms21051872.
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Although molecular mechanisms driving tumor progression have been extensively studied, the biological nature of the various populations of circulating tumor cells (CTCs) within the blood is still not well understood. Tumor cell fusion with immune cells is a longstanding hypothesis that has caught more attention in recent times. Specifically, fusion of tumor cells with macrophages might lead to the development of metastasis by acquiring features such as genetic and epigenetic heterogeneity, chemotherapeutic resistance, and immune tolerance. In addition to the traditional FDA-approved definition of a CTC (CD45-, EpCAM+, cytokeratins 8+, 18+ or 19+, with a DAPI+ nucleus), an additional circulating cell population has been identified as being potential fusions cells, characterized by distinct, large, polymorphonuclear cancer-associated cells with a dual epithelial and macrophage/myeloid phenotype. Artificial fusion of tumor cells with macrophages leads to migratory, invasive, and metastatic phenotypes. Further studies might investigate whether these have a potential impact on the immune response towards the cancer. In this review, the background, evidence, and potential relevance of tumor cell fusions with macrophages is discussed, along with the potential role of intercellular connections in their formation. Such fusion cells could be a key component in cancer metastasis, and therefore, evolve as a diagnostic and therapeutic target in cancer precision medicine.
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Naffa, Randa, Rita Padányi, Attila Ignácz, et al. "The Plasma Membrane Ca2+ Pump PMCA4b Regulates Melanoma Cell Migration through Remodeling of the Actin Cytoskeleton." Cancers 13, no. 6 (2021): 1354. http://dx.doi.org/10.3390/cancers13061354.
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We demonstrated that the plasma membrane Ca2+ ATPase PMCA4b inhibits migration and metastatic activity of BRAF mutant melanoma cells. Actin dynamics are essential for cells to move, invade and metastasize, therefore, we hypothesized that PMCA4b affected cell migration through remodeling of the actin cytoskeleton. We found that expression of PMCA4b in A375 BRAF mutant melanoma cells induced a profound change in cell shape, cell culture morphology, and displayed a polarized migratory character. Along with these changes the cells became more rounded with increased cell–cell connections, lamellipodia and stress fiber formation. Silencing PMCA4b in MCF-7 breast cancer cells had a similar effect, resulting in a dramatic loss of stress fibers. In addition, the PMCA4b expressing A375 cells maintained front-to-rear Ca2+ concentration gradient with the actin severing protein cofilin localizing to the lamellipodia, and preserved the integrity of the actin cytoskeleton from a destructive Ca2+ overload. We showed that both PMCA4b activity and trafficking were essential for the observed morphology and motility changes. In conclusion, our data suggest that PMCA4b plays a critical role in adopting front-to-rear polarity in a normally spindle-shaped cell type through F-actin rearrangement resulting in a less aggressive melanoma cell phenotype.
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van Wijk, Rien E., Yahkat Barshep та Keith A. Hobson. "On the Use of Stable Hydrogen Isotope Measurements (δ2H) to Discern Trophic Level in Avian Terrestrial Food Webs". Diversity 13, № 5 (2021): 202. http://dx.doi.org/10.3390/d13050202.
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The measurement of stable hydrogen isotope ratios (δ2H) in animal tissues is a popular means of inferring spatial origins and migratory connections. However, the use of this isotope to infer diet and potentially trophic position remains poorly understood, especially in non-aquatic terrestrial ecosystems. In many animal communities, tissue δ15N values are strongly associated with trophic position. Correlations between tissue δ2H and δ15N are expected, then, if δ2H is affected by trophic enrichment of 2H. In addition, within sites, we would expect higher tissue δ2H values in insectivorous species compared to granivores or nectarivores. We tested these hypotheses for two resident avian communities in Nigeria consisting of 30 species representing a range of dietary guilds (granivores, frugivores, nectarivores, omnivores, insectivores) by comparing feather δ2H, δ15N and δ13C values. We found considerable isotopic overlap among all guilds except granivores, with no clear pattern of enrichment in 2H with trophic position. However, at one of our sites (open scrubland), feather δ2H was positively correlated with feather δ15N (R2 = 0.30) compared to a closed canopy forest site (R2 = 0.09). Our results indicate weak evidence for predictable trophic enrichment in 2H in terrestrial environments and indicate that controlled studies are now required to definitively elucidate the behavior of H isotopes in terrestrial food webs.
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Hobson, Keith A. "Using endogenous and exogenous markers in bird conservation." Bird Conservation International 18, S1 (2008): S174—S199. http://dx.doi.org/10.1017/s0959270908000361.
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AbstractUnderstanding how avian populations are structured spatially and temporally is fundamental to their effective conservation. Protecting migratory species in one jurisdiction or period of the annual cycle may be ineffective if they periodically move to areas where they are not protected or are exposed to factors that limit populations or cause their decline. Unfortunately, for most species, our understanding of connectivity between breeding, wintering or stopover sites during the annual cycle are poorly understood and there is an urgent need to define such connections in order to achieve more effective conservation. This paper provides an overview of the methods used to mark individuals in order to track their movements. Passive exogenous markers such as numbered rings or bands are typically ineffective for most avian species. Active exogenous markers such as satellite tags have provided significant breakthroughs but are still prohibitive financially and still cannot be applied to species under 200g. Endogenous markers such as DNA markers, trace elements and stable isotopes show significant promise as a means of moving forward the field of animal tracking. The advantage of these endogenous approaches is that they depend only on sampling a population once and so are not biased by limitations of mark-recapture methods. Nonetheless, all methods have disadvantages and the path ahead must consider multiple approaches to tracking avian populations.
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Martins Junior, Angelo. "Jornadas Diferenciadas." Plural 27, no. 1 (2020): 114–44. http://dx.doi.org/10.11606/issn.2176-8099.pcso.2020.171532.
Full textAbstract:
This article question generic homogenising representations of ‘the migrant’ by providing an examination of the multivalent ways in which social differences contours migration processes. Migration scholars often reproduce generic homogenising typologies of ‘migrants’, such as the two opposing migrant analogies ‘from the Global South’ (‘the transnational migrant’, who flows through social networks from the Global South to the developed North, seeking economic gains) and ‘from the Global North’ (‘the lifestyle migrant’, who chooses to migrate from developed countries to places they believe offers them the potential of a better quality of life). Through the examination of the journeys of Brazilians in London, this article draws attention to the connections and contexts of both sending and receiving societies, as well as the diversity existing within the Brazilian population abroad. As is argued within this paper, such an analysis allows for better understanding of how the experiences of Brazilians in London are directly shaped by the intersection of multiple social markers, resulting in what I call ‘differentiated journeys’. Brazilians navigate different levels of constraints and constantly re-formulate their journeys due to their class, gender, nationality and documental status. This allow us to frame migratory experiences beyond generalizing and homogenising representations. The empirical research combines an 18-month ethnography in places of leisure with 33 in-depth interviews with Brazilians in London.
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Gray, Breda. "‘Leaving Dublin’: Photographic portrayals of post-Celtic Tiger emigration – a sociological analysis." Sociological Review 67, no. 3 (2018): 635–53. http://dx.doi.org/10.1177/0038026118795087.
Full textAbstract:
This article analyses David Monahan’s photographic portrait series of over 120 people before emigrating from post-Celtic Tiger Ireland, entitled ‘Leaving Dublin’. As a digital series that circulates across multiple media channels, it moves beyond the tradition of documentary photography into a more hybrid aesthetic, political and media environment. As well as inserting these images in multiple circulatory platforms and replicable formats, the series disrupts the dominant visual culture of emigration by expressively recasting how it is seen and thought. This article argues that the highly stylised and unsentimental aesthetic adopted by Monahan pushes the images beyond the established visual culture of sentimental departure, visualising instead transnational and multicultural histories and politics through complex circuits of migration. As such, it highlights what Mieke Bal sees as the instability of migratory culture in the city landscape. At the same time, however, it re-enacts particular social distinctions and divisions. Just as new trajectories, relationalites and stories ‘appear’ as constitutive of Dublin and contemporary mobility, so also other trajectories, relationalities and mobilities are disappeared in ways that keep an exclusionary topography and politics of mobility in place. This is evident in the insistent and persistent separation between Irish asylum-seeking/immigration and emigration-focused digital photographic projects. So, although digitisation facilitates reflexive ways of communicating contemporary migration, and Monahan’s project succeeds in forging subtle connections, it also re-enacts structured disconnection and forgetting.
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Robinson, Jane. "Prenatal programming of the female reproductive neuroendocrine system by androgens." Reproduction 132, no. 4 (2006): 539–47. http://dx.doi.org/10.1530/rep.1.00064.
Full textAbstract:
It has been clear for several decades that the areas of the brain that control reproductive function are sexually dimorphic and that the ‘programming actions’ of the male gonadal steroids are responsible for sex-specific release of the gonadotrophins from the pituitary gland. The administration of exogenous steroids to fetal/neonatal animals has pinpointed windows of time in an animals’ development when the reproductive neuroendocrine axis is responsive to the organisational influences of androgens. These ‘critical’ periods for sexual differentiation of the brain are trait- and species-specific. The neural network regulating the activity of the gonadotrophin releasing hormone (GnRH) neurones is vital to the control of reproductive function. It appears that early exposure to androgens does not influence the migratory pathway of the GnRH neurone from the olfactory placode or the size of the population of neurones that colonise the postnatal hypothalamus. However, androgens do influence the number and the nature of connections that these neurones make with other neural phenotypes. Gonadal steroid hormones play key roles in the regulation of GnRH release acting largely via steroid-sensitive intermediary neurones that impinge on the GnRH cells. Certain populations of hormonally responsive neurones have been identified that are sexually dimorphic and project from hypothalamic areas known to be involved in the regulation of GnRH release. These neurones are excellent candidates for the programming actions of male hormones in the reproductive neuroendocrine axis of the developing female.