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61.
A comparison of the efficiencies of the shotgun and the bow in neotropical forest hunting 总被引:3,自引:3,他引:0
Raymond B. Hames 《Human ecology: an interdisciplinary journal》1979,7(3):219-252
Whenever introduced into Amazonia and its neighboring regions, the shotgun has quickly replaced the bow and arrow and other aboriginal weapons of the hunt. The quick and widespread adoption of the shotgun is plainly a matter of its superiority over most aboriginal weapons. This paper compares the hunting efficiencies of the shotgun and the bow by means of a controlled field experiment among the Ye'kwana and Yanomamö Indians of the Upper Orinoco River of southern Venezuela. It also examines the impact of the shotgun on local animal populations and the economic changes brought about by the need to cash-crop in order to purchase Western hunting technology.Funds for the research and writing of this paper were made possible by an NIMH predoctoral fellowship to Napoleon A. Chagnon, Grant No. NIMH 5 R01 MH 26008-SSR. 相似文献
62.
Isolation with asymmetric gene flow during the nonsynchronous divergence of dry forest birds
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Jessica A. Oswald Isaac Overcast William M. Mauck III Michael J. Andersen Brian Tilston Smith 《Molecular ecology》2017,26(5):1386-1400
Dry forest bird communities in South America are often fragmented by intervening mountains and rainforests, generating high local endemism. The historical assembly of dry forest communities likely results from dynamic processes linked to numerous population histories among codistributed species. Nevertheless, species may diversify in the same way through time if landscape and environmental features, or species ecologies, similarly structure populations. Here we tested whether six co‐distributed taxon pairs that occur in the dry forests of the Tumbes and Marañón Valley of northwestern South America show concordant patterns and modes of diversification. We employed a genome reduction technique, double‐digest restriction site‐associated DNA sequencing, and obtained 4407–7186 genomewide SNPs. We estimated demographic history in each taxon pair and inferred that all pairs had the same best‐fit demographic model: isolation with asymmetric gene flow from the Tumbes into the Marañón Valley, suggesting a common diversification mode. Overall, we also observed congruence in effective population size (Ne) patterns where ancestral Ne were 2.9–11.0× larger than present‐day Marañón Valley populations and 0.3–2.0× larger than Tumbesian populations. Present‐day Marañón Valley Ne was smaller than Tumbes. In contrast, we found simultaneous population isolation due to a single event to be unlikely as taxon pairs diverged over an extended period of time (0.1–2.9 Ma) with multiple nonoverlapping divergence periods. Our results show that even when populations of codistributed species asynchronously diverge, the mode of their differentiation can remain conserved over millions of years. Divergence by allopatric isolation due to barrier formation does not explain the mode of differentiation between these two bird assemblages; rather, migration of individuals occurred before and after geographic isolation. 相似文献
63.
Antagonism and conflict within newly resident UK Polish migrants has been typically related to labour market competition. Without denying the relevance of this argument, we argue that explanations of antagonism within the Polish community should also take into account the role of a Polish intelligentsia habitus. This habitus provides a repertoire of available discursive strategies used for interpreting antagonistic and “risk” situations both in Poland and among Poles abroad. It is argued that not only can this intelligentsia habitus critically legitimize intergroup inequalities in status and symbolic power but also may impact on the patterns of a migrant’s integration, linkage to social networks, access to different capital resources, and interactions with the indigenous population. 相似文献
64.
Sophie Watson 《Ethnic and racial studies》2017,40(15):2635-2652
Urbanists seeking to undermine or challenge pessimistic accounts of prevalent racism and anti-migrant feeling in cities have articulated and mobilized discourses of everyday multiculturalism, cosmopolitanism, multicultural drift, rubbing along and transculturalism. This paper, through a range of ethnographic methods, explores these notions in a locality of Camden, North London, arguing for the notion of “making multiculturalism” as a way of emphasizing how everyday multiculturalism is situated and plays out in specific local socio-cultural and historical contexts. In so doing, it considers the extent to which the locality follows the perceived trend in many globalized cities towards the acquisition of habits or capacities for diverse individuals to share space with relative harmony and tolerance. Second, it seeks to explore what are the elements and components of everyday multiculturalism, cosmopolitanism or conviviality assembled in this space. Third, it asks the question – how are these multicultural settlements disrupted and fractured? 相似文献
65.
Juliet Pietsch 《Ethnic and racial studies》2017,40(14):2463-2480
A review of the research literature on migrant voting in Australia shows that the “ethnic vote” has almost disappeared now that migrants tend to vote in a similar way to the rest of the population according to traditional class cleavages. In addition, it is argued that migrants in Australia predominantly reside in safe Labor seats that are represented by cabinet or shadow cabinet ministers. As such their group-based interests are often neglected by the major parties. Using findings from the ABS census and the 1993–2013 AES, this article re-examines whether there is a migrant vote, and if so, the extent to which migrant voting patterns have changed since the 1990s when the migrant and ethnic vote reached its peak. This study reveals patterns of migrant voting among certain birthplace subgroups that are more volatile than in previous decades but at the same time distinctive. 相似文献
66.
Species richness is predicted to increase in the northern latitudes in the warming climate due to ranges of many southern species expanding northwards. We studied changes in the composition of the whole avifauna and in bird species richness in a period of already warming climate in Finland (in northern Europe) covering 1,100 km in south–north gradient across the boreal zone (over 300,000 km2). We compared bird species richness and species‐specific changes (for all 235 bird species that occur in Finland) in range size (number of squares occupied) and range shifts (measured as median of area of occupancy) based on bird atlas studies between 1974–1989 and 2006–2010. In addition, we tested how the habitat preference and migration strategy of species explain species‐specific variation in the change of the range size. The study was carried out in 10 km squares with similar research intensity in both time periods. The species richness did not change significantly between the two time periods. The composition of the bird fauna, however, changed considerably with 37.0% of species showing an increase and 34.9% a decrease in the numbers of occupied squares, that is, about equal number of species gained and lost their range. Altogether 95.7% of all species (225/235) showed changes either in the numbers of occupied squares or they experienced a range shift (or both). The range size of archipelago birds increased and long‐distance migrants declined significantly. Range loss observed in long‐distance migrants is in line with the observed population declines of long‐distance migrants in the whole Europe. The results show that there is an ongoing considerable species turnover due to climate change and due to land use and other direct human influence. High bird species turnover observed in northern Europe may also affect the functional diversity of species communities. 相似文献
67.
Fr?nzi Korner-Nievergelt Pius Korner-Nievergelt Edi Baader Luzius Fischer Werner Schaffner Matthias Kestenholz 《Journal of Ornithology》2008,149(4):579-586
We analysed the number of autumn migrants at a bird ringing station over 41 years in the Jura mountains of Switzerland. For
12 irruptive or potentially irruptive bird species, the correlations between their numbers per year were calculated and the
species were clustered accordingly. We found high correlations in the number of migrants between the Coal Tit Periparus ater, Great Tit Parus major and Blue Tit Cyanistes caeruleus. Most correlations of passage number between species pairs changed dramatically over time. Only Blue Tit and Coal Tit showed
continuously high correlation in this respect. The variation and changes over time in between-species correlations in the
number of migrants needs more attention. 相似文献
68.
The species composition of typically marine fishes in the lower course and mouth area of the Tumen River (Sea of Japan) is examined based on original faunistic collections and literature data. Thirty-three species belonging to 19 families were recorded. The ratio of species of boreal and subtropical origins was found; temporary and seasonal migrants were identified. Some species (Platichthys stellatus, Myoxocephalus stelleri, Strongylura anastomella, and Mugil cephalus) can be considered indicators of the state of the environment. It is noted that yearly surveys of the marine fish composition in the river zone are needed for monitoring climatic and anthropogenic influences. 相似文献
69.
This paper outlines population trends (with confidence intervals) for 49 species in woodland habitats in Britain as monitored by the British Trust for Ornithology's (BTO) Common Bird Census (CBC) between 1967 and 1999. Additionally, the possible causes of these population trends are investigated by relating the ecological characteristics of species to the degree of population change they have undergone over different time periods. Over the whole period, 17 species showed significant decreases in abundance and 12 species showed significant increases. Whilst population trajectories were diverse, long-distance migrants showed more negative trends than other species and the timing of the changes in their populations was related to their wintering latitude, suggesting that these species may be suffering from environmental changes in the non-breeding season. There was also support for habitat specializations being related to population changes, with species classified as scrub and understorey specialists declining on average, but this was only evident across the entire study period. Additionally, species eating seeds in summer declined and those eating vegetation and making use of the agricultural landscape matrix increased. Therefore wide-scale factors such as landscape-scale processes or processes operating outside of Britain appear to be important in addition to local habitat change, especially for long-distance migrants. 相似文献
70.
Rebecca D. Fink Catherine A. Lindell Emily B. Morrison Rakan A. Zahawi and Karen D. Holl 《Restoration Ecology》2009,17(4):479-486
Efforts to restore tropical forest in abandoned pasture are likely to be more successful when bird visitation is promoted because birds disperse seeds and eat herbivorous arthropods that damage leaves. Thus, it is critical to understand bird behavior in relation to different restoration strategies. We measured the likelihood of visitation, number of visits, and duration of visits for all birds and for Cherrie's Tanager ( Ramphocelus costaricensis ), a common seed disperser, in five sizes of forest restoration patches planted with four tree species in southern Costa Rica. We predicted that the largest patches, and the tree species with the greatest canopy cover, would be visited most frequently and have the longest visits because we assumed that these patch types had the greatest food resources and the lowest predation risk. We found that birds were more likely to visit large patches and the tree species with the highest canopy cover ( Inga edulis ). Birds visited Inga trees more often and stayed in Inga and Erythrina poeppigiana trees for longer periods of time than in other tree species. We found similar results for Cherrie's Tanagers. Thus, we identified two factors, tree species and patch size, which may be manipulated in restoration projects to increase bird visitation. 相似文献