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1.
After being free of rabies of terrestrial mammals since 1988, an outbreak of rabies occurred on the Island of Newfoundland in December 2002 and continued into the middle of 2003. Twenty-one cases, all due to the arctic fox strain of rabies virus, were reported. To explore the immediate origins of this outbreak, viruses from the Newfoundland epizootic were genetically compared to two other rabies viruses recovered in mid-2002 from Cartwright, a mainland coastal community near the Island. While all Island isolates from the 2002-03 outbreak were genetically very similar, consistent with a single introduction from the mainland, they were phylogenetically quite distant from the two samples from Cartwright. A broader-based study examined the relationships between the Island viruses and arctic fox strain viruses originating from across Canada over a period of 14 yr. This analysis indicated that the Newfoundland outbreak viruses were most similar to a variant identified in Labrador in 2004 but also widely distributed in northern Quebec both before and after the Newfoundland incursion. The eastern coastline of mainland Labrador has harbored a particularly large number of variants during the study period, some of which have not been detected elsewhere. A small number of Greenland isolates included in this study were dispersed within the clades of the Canadian samples rather than forming a discrete cluster, an observation that may underline the relative ease of movement of the rabies arctic lineage between these two countries as a result of animal movements over pack ice.  相似文献   

2.
A study was conducted to determine the prevalence and geographical distribution of Sarcocystis spp. infecting 2 subspecies of caribou (Rangifer tarandus) inhabiting Newfoundland and Labrador and its potential definitive hosts. Muscle samples of caribou were obtained, primarily from hunters, and feces of red foxes (Vulpes vulpes) and wolves (Canis lupus), from trappers, and Husky dogs (Canis familiaris), from owners. Histological sections of muscle and flotation methods for feces were used for parasitic detection. Sarcocystis sp. infected more than 50% of barren-ground caribou (R. t. tarandus) from 4 locations in Newfoundland, but it was significantly greater in the north, where 99% of woodland caribou (R. t. caribou) from Labrador harbored the infection. Sporocysts were observed in 27 of 32 red foxes from eastern and northern Newfoundland, whereas 15 of 15 wolves and 22 of the 38 Husky dogs were infected. Wolves and red foxes probably acquired the infection through scavenging, and Husky dogs, from meat they were fed.  相似文献   

3.
Melanocortin 1 receptor variation in the domestic dog   总被引:23,自引:0,他引:23  
The melanocortin 1 receptor (Mc1r) is encoded by the Extension locus in many different mammals, where a loss-of-function causes exclusive production of red/yellow pheomelanin, and a constitutively activating mutation causes exclusive production of black/brown eumelanin. In the domestic dog, breeds with a wild-type E allele, e.g., the Doberman, can produce either pigment type, whereas breeds with the e allele, e.g., the Golden Retriever, produce exclusively yellow pigment. However, a black coat color in the Newfoundland and similar breeds is thought to be caused by an unusual allele of Agouti, which encodes the physiologic ligand for the Mc1r. Here we report that the predicted dog Mc1r is 317 residues in length and 96% identical to the fox Mc1r. Comparison of the Doberman, Newfoundland, Black Labrador, Yellow Labrador, Flat-coated Retriever, Irish Setter, and Golden Retriever revealed six sequence variants, of which two, S90G and R306ter, partially correlated with a black/brown coat and red/yellow coat, respectively. R306ter was found in the Yellow Labrador, Golden Retriever, and Irish Setter; the latter two had identical haplotypes but differed from the Yellow Labrador at three positions other than R306ter. In a larger survey of 194 dogs and 19 breeds, R306ter and a red/yellow coat were completely concordant except for the Red Chow. These results indicate that the e allele is caused by a common Mc1r loss-of-function mutation that either reoccurred or was subject to gene conversion during recent evolutionary history, and suggest that the allelic and locus relationships for dog coat color genes may be more analogous to those found in other mammals than previously thought.  相似文献   

4.
Capelin (Mallotus villosus) is a commercially exploited, key forage-fish species found in the boreal waters of the North Pacific and North Atlantic Oceans. We examined the population structure of capelin throughout their range in the Canadian northwest Atlantic Ocean using genetic-based methods. Capelin collected at ten beach and five demersal spawning locations over the period 2002 through 2008 (N = 3,433 fish) were genotyped using six polymorphic microsatellite loci. Temporally distinct samples were identified at three beach spawning locations: Chance Cove, Little Lawn and Straitsview, Newfoundland. Four capelin stocks are assumed for fisheries management in the northwest Atlantic Ocean based on meristics, morphometrics, tag returns, and seasonal distribution patterns. Our results suggested groupings that were somewhat different than the assumed structure, and indicate at least seven genetically defined populations arising from two ancestral populations. The spatial mosaic of capelin from each of the two basal cluster groups explains much of the observed geographic variability amongst neighbouring samples. The genetic-defined populations were resolved at Jost’s D est ≥ 0.01 and were composed of fish collected 1) in the Gulf of St. Lawrence, 2) along the south and east coasts of Newfoundland, 3) along coastal northern Newfoundland and southern Labrador, 4) along coastal northern Labrador, 5) near the Saguenay River, and at two nearshore demersal spawning sites, 6) one at Grebes Nest off Bellevue Beach on the east coast of Newfoundland, and 7) one off the coast of Labrador at Domino Run. Moreover, the offshore demersal spawners on the Scotian Shelf and Southeast Shoal appeared to be related to the inshore demersal spawners at Grebes Nest and in Domino Run and to beach spawners from the Gulf of St. Lawrence.  相似文献   

5.
Three genes, Mc1r, Agouti, and CBD103, interact in a type-switching process that controls much of the pigmentation variation observed in mammals. A deletion in the CBD103 gene is responsible for dominant black color in dogs, while the white-phased black bear (“spirit bear”) of British Columbia, Canada, is the lightest documented color variant caused by a mutation in Mc1r. Rare all-white animals have recently been discovered in a new northeastern population of the coyote in insular Newfoundland and Labrador, Canada. To investigate the causative gene and mutation of white coat in coyotes, we sequenced the three type-switching genes in white and dark-phased animals from Newfoundland. The only sequence variants unambiguously associated with white color were in Mc1r, and one of these variants causes the amino acid variant R306Ter, a premature stop codon also linked to coat color in Golden Retrievers and other dogs with yellow/red coats. The allele carrying R306Ter in coyotes matches that in the Golden Retriever at other variable amino acid sites and hence may have originated in these dogs. Coyotes experienced introgression with wolves and dogs as they colonized northeastern North America, and coyote/Golden Retriever interactions have been observed in Newfoundland. We speculate that natural selection, with or without a founder effect, may contribute to the observed frequency of white coyotes in Newfoundland, as it has contributed to the high frequency of white bears, and of a domestic dog-derived CBD allele in gray wolves.  相似文献   

6.
S Ratnam  C B Head  R W Butler 《CMAJ》1986,134(8):905-907
Epidemiologic knowledge of hepatitis D virus (HDV) infection is limited. A seroepidemiologic study was undertaken to determine the prevalence of the infection in Newfoundland and Labrador. Between October 1983 and October 1985 over 200 people were recognized through routine serodiagnosis and screening as having hepatitis B seromarkers. A total of 223 serum samples from 186 of these people were tested for anti-HDV. The subjects were mainly asymptomatic carriers of hepatitis B surface antigen or patients with acute or chronic hepatitis B from the native Indian and Inuit and the non-native populations. None of the serum samples were positive for anti-HDV. The absence of anti-HDV in a substantial number of people in the province who are infected with hepatitis B virus is strong evidence that HDV infection is not prevalent in the local population, including native people.  相似文献   

7.
Polymorphisms at five microsatellite DNA loci provide evidence that Atlantic cod Gadus morhua inhabiting Gilbert Bay, Labrador are genetically distinguishable from offshore cod on the north-east Newfoundland shelf and from inshore cod in Trinity Bay, Newfoundland. Antifreeze activity in the blood suggests that Gilbert Bay cod overwinter within the Bay. Gilbert Bay cod are also smaller (weight and length) for their age and consequently less fecund for their age, than cod elsewhere within the northern cod complex. The productivity and recruitment potential of coastal cod off Labrador may thus be much lower than that of offshore northern cod or of inshore cod farther south, implying that a more conservative management strategy may be required for cod from coastal Labrador than traditionally practised for northern cod inhabiting less harsh environments. Relatively high F ST and R ST measures of population structure suggest that important barriers to gene flow exist among five components that include two inshore (Gilbert and Trinity Bay) and three offshore cod aggregations on the north-east Newfoundland Shelf and the Grand Bank. D A and D SW estimates of genetic distance that involve Gilbert Bay cod are approximately three- and 10–fold larger, respectively, than estimates not involving Gilbert Bay cod. The differences between inshore cod from Gilbert Bay and Trinity Bay raise the possibility that other genetically distinguishable coastal populations may exist, or may have existed prior to the northern cod fishery collapse. Harvesting strategies for northern cod should recognize the existence of genetic diversity between inshore and offshore components as well as among coastal components.  相似文献   

8.
Among highly migratory fish species, nursery areas occupied by juveniles often differ from adult habitats. To better understand the spatial dynamics of Canada's Northern cod stock, juveniles caught off the east coast of Newfoundland and Labrador were compared to adults from the same region as well as individuals from other areas in Atlantic Canada using double-digest restriction site-associated DNA sequencing–derived single nucleotide polymorphisms. A reduced proportion of homozygotes with a chromosomal inversion located in linkage group 1 (LG1) was detected between juvenile and adult samples in the Northern cod stock region, potentially indicating age-dependent habitat use or ontogenetic selection for attributes associated with the many genes located in LG1. No selectively neutral genetic differences were found between samples from the Northern cod stock; nevertheless, significant differences were found between some of these samples and cod collected from St. Pierre Bank, Bay of Fundy, Browns Bank and the southern Scotian Shelf. Clustering analysis of variants at neutral loci provided evidence for three major genetic units: (a) the Newfoundland Atlantic Coast, (b) eastern and southern Gulf of St. Lawrence and Burgeo Bank and (c) the Bay of Fundy, Browns Bank and southern Scotian Shelf. Both adaptive and neutral population structure within the Northern cod stock should be considered by managers to promote demographic rebuilding of the stock.  相似文献   

9.
This is the first published report of tardigrades in Newfoundland and Labrador. Twenty-six species have been identified so far, including four new records for Canada and one new record for North America. Although there is some overlap of species with those found in earlier Canadian studies, there are some interesting discrepancies. The rare occurrence and restricted distribution of the very few heterotardigrades (three species and 30 specimens) found so far in Newfoundland is noteworthy, as is the occurrence of several tardigrade species whose former records have been mainly for Greenland. It appears the environmental conditions in Newfoundland can support a number of species that would normally be restricted to a more northerly distribution. A comparison of the species found in Newfoundland with those of a number of other northern countries suggests that the Newfoundland species are most similar to those found in Greenland and mainland Canada.  相似文献   

10.
The delimitation award of the Tribunal in the Second Phase of the Arbitration between Newfoundland and Labrador and Nova Scotia is analyzed in light of the terms of reference establishing the Tribunal and the positions of the Parties throughout the delimitation phase of the Arbitration. The application of the principles of international law governing maritime boundary delimitation and the reasoning of the Tribunal in the creation of this boundary puts the Newfoundland and Labrador-Nova Scotia boundary on a par with international maritime boundary awards.  相似文献   

11.
In conservation genetics and management, it is important to understand the contribution of historical and contemporary processes to geographic patterns of genetic structure in order to characterize and preserve diversity. As part of a 10-year monitoring program by the Government of Newfoundland and Labrador, Canada, we measured the population genetic structure of the world's most northern native populations of brook trout (Salvelinus fontinalis) in Labrador to gather baseline data to facilitate monitoring of future impacts of the recently opened Trans-Labrador Highway. Six-locus microsatellite profiles were obtained from 1130 fish representing 32 populations from six local regions. Genetic diversity in brook trout populations in Labrador (average H(E)= 0.620) is within the spectrum of variability found in other brook trout across their northeastern range, with limited ongoing gene flow occurring between populations (average pairwise F(ST)= 0.139). Evidence for some contribution of historical processes shaping genetic structure was inferred from an isolation-by-distance analysis, while dual routes of post-Wisconsinan recolonization were indicated by STRUCTURE analysis: K= 2 was the most likely number of genetic groups, revealing a separation between northern and west-central Labrador from all remaining populations. Our results represent the first data from the nuclear genome of brook trout in Labrador and emphasize the usefulness of microsatellite data for revealing the extent to which genetic structure is shaped by both historical and contemporary processes.  相似文献   

12.
A well-preserved assemblage of dinoflagellate cysts, probably of Flandrian age, was recovered from two piston cores on the Grand Banks, off Newfoundland, Canada. The assemblage, dominated by the dinoflagellate cyst species Operculodinium centrocarpum, is regarded as a mixed Gulf Stream/North Atlantic Drift—Labrador current association.  相似文献   

13.
14.
L'hépatite C     
P. R. Gully  M. L. Tepper 《CMAJ》1997,156(10):1429-1430
Across Canada, residency programs are attempting to train more physicians to practise in rural and remote areas. The Northern Family Education Program developed in Newfoundland and Labrador is proving that physicians can learn to like life in remote areas.  相似文献   

15.
The relationship between sea ice and the phytoplankton springbloom over the Newfoundland and Labrador shelves is examinedusing remotely-sensed chlorophyll data and sea-ice data forthe period 1998–2004. A regression analysis between thetwo data sets shows that the retreat of sea ice precedes thespring bloom, and the inter-annual variation of the spring bloomis closely correlated with the start time of ice retreat. Thespring bloom off Canada's east coast usually starts on the easternGrand Banks. Here, the water properties are strongly influencedby sea ice on the Newfoundland shelves in early spring whenaccelerated ice melting causes the ice edge to retreat northand the melt water is advected south by the Labrador Current.After the ice retreat, the water on the eastern Grand Banksis rapidly stratified and the mixed layer shallows as a resultof surface freshening. The shallow mixed layer promotes phytoplanktongrowth. The regression analysis also reveals that an early springbloom or ice retreat tends to prolong the duration of the springbloom.  相似文献   

16.
Plankton samples were collected in the Northwest Atlantic on the Grand Banks of Newfoundland in August 1976 and on Flemish Cap in March 1977. The samples were taken using a Hardy Continuous Plankton Recorder towed at a depth of 9.1 m. On the Grand Banks the following species were found: Ceratium arcticum (Ehrenberg), C. longipes (Ehrenberg), C. lineatum (Ehrenberg), C. macroceros (Ehrenberg), C. fusus (Ehrenberg). C. tripos (Müller) and Ceratium spp. Other microplankton found in the samples included Radiolaria, Globigerina humilis (Brady), and the tintinnid ciliates Tintinnopsis cylindrica (Daday) and Tintinnopsis spp. In the samples from Flemish Cap only a single species of diatom was found in small numbers. The paucity of individuals in these samples is most probably related to the season of the survey, winter. The population density of C. arcticum had a patchiness with a length scale on the order of 104 m. The plankton tow on the Grand Banks was parallel to the north-south axis of the Labrador Current. This patchiness scale on the order of 104 m may reflect a meandering of the Labrador Current.  相似文献   

17.
Coevolution is increasingly recognized as an important process structuring geographic variation in the form of selection for many populations. Here we consider the importance of a geographic mosaic of coevolution to patterns of crossbill (Loxia) diversity in the northern boreal forests of North America. We examine the relationships between geographic variation in cone morphology, bill morphology, and feeding performance to test the hypothesis that, in the absence of red squirrels (Tamiasciurus hudsonicus), black spruce (Picea mariana) has lost seed defenses directed at Tamiasciurus and that red crossbills (L curvirostra) and black spruce have coevolved in an evolutionary arms race. Comparisons of cone morphology and several indirect lines of evidence suggest that black spruce has evolved defenses in response to Tamiasciurus on mainland North America but has lost these defenses on Newfoundland. Cone traits that deter crossbills, including thicker scales that require larger forces to separate, are elevated in black spruce on Newfoundland, and larger billed crossbills have higher feeding performances than smaller billed crossbills on black spruce cones from Newfoundland. These results imply that the large bill of the Newfoundland crossbill (L. c. percna) evolved as an adaptation to the elevated cone defenses on Newfoundland and that crossbills and black spruce coevolved in an evolutionary arms race on Newfoundland during the last 9000 years since glaciers retreated. On the mainland where black spruce is not as well defended against crossbills, the small-billed white-winged crossbill (L leucoptera leucoptera) is more efficient and specializes on seeds in the partially closed cones. Finally, reciprocal adaptations between crossbills and conifers are replicated in black spruce and Rocky Mountain lodgepole pine (Pinus contorta ssp. latifolia), with coevolution most pronounced in isolated populations where Tamiasciurus are absent as a competitor. This study further supports the role of Tamiasciurus in determining the selection mosaic for crossbills and suggests that a geographic mosaic of coevolution has been a prominent factor underlying the diversification of North American crossbills.  相似文献   

18.
Entanglements of large whales in commercial fisheries in Newfoundland and Labrador, Canada, have been consistently recorded since 1979, as part of a program aimed at releasing captured animals and reducing costs to fishermen. This data set represented an opportunity to identify fisheries posing particular entanglement risks to local whale populations. Data were assessed over the periods 1979–1992 and 1993–2008, corresponding to distinct phases in fisheries distribution and intensity. Between 1979 and 2008, 1,209 large whale entanglements were recorded in Newfoundland and Labrador. These were mostly humpback whales (Megaptera novaeangliae; 80%) and minke whales (Balaenoptera acutorostrata; 15%). Dramatic declines in reported inshore whale entanglement rates were observed following the 1992 moratorium on Atlantic cod (Gadus morhua) fisheries. Recently, more entanglements have been reported further offshore, largely due to expansion of fisheries targeting snow crab (Chionoecetes opilio). For all whale species, entanglement rates and associated mortality rates varied considerably in different fishing gear. Fractions of humpback and minke whales found dead in different fishing gear differed substantially, with minke whales far more likely to be found dead than humpback whales.  相似文献   

19.
This study explores the association of 24 polychaete species with sandy and muddy habitats located in a sub-arctic fjord, and across Atlantic Canada including Labrador, Newfoundland, and the Gulf of St. Lawrence. Key characters used to facilitate species identification are also summarized. Within Bonne Bay, distinctive polychaete assemblages were associated with specific sediment types and polychaete species richness and density were significant both predictors of corresponding total (infaunal) density and species richness. Polychaetes were denser and more diverse in sandy sediments, partly because sandy locales were associated with the outer portion of the bay, and therefore were closer to the more productive and diverse Gulf of St. Lawrence. In general, species that occupied both sediment types were more widely distributed within Bonne Bay and across the region. The biogeography of most species also suggests that the Bonne Bay fauna is transitional between Labrador and Acadian biogeographic provinces.  相似文献   

20.
Bryan L.  Sage 《Ibis》1968,110(1):1-16
An analysis is presented of observations made in the North Atlantic from 14 August to 10 September 1966, and comparisons are made with previously published data relating to this area. The majority of the records were obtained during transects along latitudes 55° N. and 58° N., but other data were collected in Labrador and Newfoundland coastal waters. During the period spent at sea 30 species were recorded, including five passerine species that came aboard ship. Manx Shearwaters were seen in Newfoundland waters where there have been few previous records. The record of a Balearic Shearwater appears to be the most northerly to date. Some evidence of correlation was found between the numbers of Great Shearwaters seen and the surface water temperature, but there was little evidence of correlation in the case of the Fulmar. Other points of interest are the records of moult in the Great Shearwater, and the records of Grey Phalaropes and Sabine's Gulls. An analysis of the skua movements suggests that the Arctic Skuas seen originated from Scandinavia, the Great Skuas from Iceland and the Pomarine and Long-tailed Skuas from the Canadian arctic.  相似文献   

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