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1.
Christof Janko Stefan Linke Thomas Romig Dorothea Thoma Wolfgang Schröder Andreas König 《European Journal of Wildlife Research》2011,57(5):1033-1042
This study investigated the epidemiological and ecological factors to assess the infection pressure of alveolar echinococcosis
to human which are living in villages and small towns. Foxes and fox faeces were examined for Echinococcus multilocularis and foxes were observed by radio telemetry in Upper Bavaria, Germany. Forty-three percent of the village foxes (n = 65) had been infected with E. multilocularis. This prevalence rate did not differ significantly from the prevalence among rural foxes, which was 39% (n = 33; χ
2 = 0.12, df = 1, p = 0.727) determined by the intestinal scraping technique. PCR analyses of fox faeces showed a higher infection rate of 35%
(n = 26) among rural foxes than among foxes in villages and small towns (26%, n = 69; χ
2 = 0.68, df = 1, p = 0.411). One quarter of the fox faecal samples come from private gardens of residents. The radio-tracking study on 17 foxes
showed that foxes preferred the built-up area and grassland outside the villages. Village foxes concentrated their activity
within a range of 500 m around the settlement. Sixty-four percent of all bearings for radio-tracked foxes showed positions
in areas outside the town, and 36% of bearings were within the settlement. Village foxes, which are infected with E. multilocularis, are able to carry the parasite continuously into settlements and fox faeces present an immediate source of infection to
humans, especially within their gardens. Therefore, foxes are responsible for environmental E. multilocularis egg contamination in the vicinity of humans, leading to an infection risk to inhabitants of villages and small towns. 相似文献
2.
Test of a digestion optimization model: effect of variable-reward feeding schedules on digestive performance of a migratory bird 总被引:1,自引:0,他引:1
Birds on migration often alternate between feeding and nonfeeding periods, in part because food resources may be patchily
distributed and in part because birds on migration may adopt a risk-prone foraging strategy characterized by selection of
variable rather than constant food rewards. Optimal digestion models predict that increases in intermeal interval like those
encountered by some migratory birds should result in longer retention time of digesta and higher digestive efficiency if birds
are maximizing their rate of energy intake. We tested these predictions by comparing residence time of digesta and extraction
efficiency of lipid for captive yellow-rumped warblers (Dendroica coronata) feeding adlibitum and when we added intervals of time when the birds received no food. We increased the likelihood that the warblers were maximizing
their rate of energy intake by increasing light levels during spring to induce hyperphagia (treatment birds (16L:8D light:
dark cycle) ate 2.13 ± 0.14 g dry food day−1 (n = 8) while control birds (10L:14D) ate 1.25 ± 0.03 g dry food day−1 (n = 6)). Treatment birds offered food only every other 2–3 h ate 50% more during the 4-h test period than when they were always
feeding adlibitum. Despite these differences in food intake, extraction efficiency of glycerol trioleate remained high and constant (93%),
and mouth-to-anus total mean retention time (TMRT) did not change (overall mean: 54.8 ± 6.0 min). Residence time of lipid
in the stomach increased whereas residence time of lipid in the intestine decreased when birds fed only every other 2–3 h
compared to when birds always fed ad libitum. None of the results were consistent with the predictions of the optimal digestion model unless we assume that birds were
minimizing their feeding time rather than maximizing their rate of energy gain. Furthermore, the ability of yellow-rumped
warblers to maintain high extraction efficiency with no change in TMRT suggests some spare digestive capacity when food intake
increases by as much as 50%.
Received: 14 June 1997 / Accepted: 20 November 1997 相似文献
3.
Information on the foraging of White Storks on rubbish dumps, a novel behaviour in Central European populations, is presented.
Observations were first made in 1999 and to date; they have been recorded on sixteen locations in Poland. From one to 348
White Storks (median = 2, N = 116) were observed on rubbish dumps, and most of the records (86%) were of 1–3 birds. Birds foraging on rubbish dumps were
recorded from late March to early September, but the highest numbers were seen during the summer months. Most of the birds
(77%, N = 171) were recorded foraging directly on an area where rubbish had been thrown, while a minor fraction (16%) was seen on
neighbouring recultivated grassy areas. Dumps were used as an additional food source probably in areas where natural foraging
grounds are limited. The increased frequency of observations during the summer months probably resulted from the greater nutritional
needs of large nestlings which force the adults to find alternative food sources or foraging habitat shift by non-breeding
birds. 相似文献
4.
Sharon Gursky 《International journal of primatology》2010,31(1):117-131
One of the most widely accepted explanations for the difference in the sex bias between mammals and birds is that male-biased
dispersal in mammals is due to the preponderance of polygynous mating systems exhibited by this class, whereas birds are predominantly
monogamous. Spectral tarsiers (Tarsius spectrum) are unusual in that they exhibit variation in its mating system. Although the majority of spectral tarsier groups are monogamous,
ca. 15% are polygynous. If mating system influences dispersal, then I predicted that the polygynous groups would exhibit male
biased dispersal whereas I predicted that the dispersal patterns of the monogamous groups would be analogous to that exhibited
by birds, specifically female biased. Alternatively, I hypothesized that ecological variation may influence dispersal habits
in this species. Specifically, I predicted that polygynous groups would exhibit greater habitat quality than monogamous groups.
The 2 hypotheses are not mutually exclusive. On the basis of 14 individuals birdbanded between 1994 and 1999, I determined
that individuals of both sexes were equally likely to disperse (males, n = 5; females, n = 9). Males dispersed twice as far as females did. The mean dispersal distance for males was 660 m, and for females it was
266 m. Females (77%) were more likely to form a territory adjacent to the parental territory than were males (20%). Individuals
exhibited relatively high amounts of site fidelity (86%) that were related to physical characteristics of the sleeping site.
Adults that dispersed a second time (n = 4) initially resided in trees that were shorter and had a smaller diameter-at-breast height than the trees of individuals
that exhibited site fidelity. The results of my study partly support the parental mating system hypothesis and also support
the habitat quality hypothesis. 相似文献
5.
Bisson Isabelle-A. Marra Peter P. Burtt Jr Edward H. Sikaroodi Masoumeh Gillevet Patrick M. 《Microbial ecology》2009,58(1):212-220
Migratory birds can be efficient dispersers of pathogens, yet we know little about the effect of migration and season on the
microbial community in avian plumage. This is the first study to describe and compare the microbial plumage community of adult
and juvenile migratory birds during the annual cycle and compare the plumage community of migrants to that of resident birds
at both neotropical and nearctic locations. We used length heterogeneity PCR (16S rRNA) to describe the microbial assemblage
sampled from the plumage of 66 birds in two age classes and from 16 soil samples. Resident birds differed significantly in
plumage microbial community composition from migrants (R ≥ 0.238, P < 0.01). Nearctic resident birds had higher plumage microbial diversity than nearctic migrants (R = 0.402, P < 0.01). Plumage microbial composition differed significantly between fall premigratory and either breeding (R ≥ 0.161, P < 0.05) or nonbreeding stages (R = 0.267, P < 0.01). Six bacterial operational taxonomic units contributed most to the dissimilarities found in this assay. Soil microbial
community composition was significantly different from all samples of plumage microbial communities (R ≥ 0.700, P < 0.01). The plumage microbial community varies in relation to migration strategy and stage of the annual cycle. We suggest
that plumage microbial acquisition begins in the first year at natal breeding locations and reaches equilibrium at the neotropical
wintering sites. These data lead us to conclude that migration and season play an important role in the dynamics of the microbial
community in avian plumage and may reflect patterns of pathogen dispersal by birds. 相似文献
6.
To detect Babesia-infected Ixodes persulcatus Shulze in a suburb of St. Petersburg, Russia, 738 adult ticks were studied using Babesia specific primers and PCR techniques. The entire sample (more than 1,200 individuals) was screened for the presence of Borrelia spp., Ehrlichia spp. and tick-borne encephalitis virus (TBEV). All 7 ticks infected with Babesia microti, were also infected with other pathogens (all 7 among 417 infected ticks, zero amongst the remaining 321 naive ones (χ2 = 5.25, p < 0.05). Babesia microti occurred twice with Borrelia afzelii, 3 times with Borrelia garinii, once with both, and once with both B. garinii and TBEV. The prevalence of infection with Borrelia spp. was 34.0%, with Ehrlichia spp. 6.2%, with TBEV 1.5%, and with Ba microti 0.9%. Babesia microti infection was not found in combination with Ehrlichia sp. or Borrelia burgdorferi sensu stricto. The latter pathogen (prevalence 2.6%), just like Ba. microti, was not encountered as a monoinfection. The data suggest that Ba. microti infection can only survive in I. persulcatus in combination with Borrelia spp. (7 of 7 infections). The disease in humans is more severe and longer-lasting when more than one pathogen is involved.
Our observations show that the well known St. Petersburg focus of tick-borne encephalitis and Lyme disease is also a focus
of ehrlichiosis and babesiosis.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
7.
R. P. Wilson B. Alvarrez L. Latorre D. Adelung B. Culik R. Bannasch 《Polar Biology》1998,19(6):407-413
The movements of gentoo penguins (Pygoscelis papua) in Antarctica were studied by equipping a total of 37 birds captured at Ardley Island, South Shetlands between December
1991 and May 1996 with position-determining devices. Information on area usage was derived from 20 of these devices and covered
the incubation period (N = 3 birds), the chick-rearing period (N = 14 birds) and the over-wintering period (N = 3 birds). During incubation birds only ventured further than 50 km from the colony 20% of the time and no individual ranged
further than 200 km from the colony. In contrast, no individuals attending chicks ranged further than 16 km from the colony.
During winter the maximum distance ranged from the colony was 268 km. Mean distances between the birds and the colony were
80, 81 and 127 km. Individual birds tended to associate with one spot, making short (10 day) forays away before returning
to nodal areas. The ranging capacity of gentoo penguins appears considerably less than that of sympatric congeners and may
reflect the ability of gentoo penguins to dive deeper and thus exploit prey not accessible to congeners.
Received: 1 October 1997 / Accepted: 3 February 1998 相似文献
8.
Sixty nine hammerhead sharks, Sphyrna lewini, were tagged at Malpelo Island (Colombia) with ultrasonic transmitters during March 2006, 2007 and 2008, as part of a study
to understand their residency at the island and their horizontal and vertical movements. Five sharks visited Cocos Island,
627 km distant from Malpelo. One of the sharks that appeared at Cocos Island also visited the Galapagos Islands, 710 km from
Cocos, a month later. There is connectivity of Sphyrna lewini between Malpelo, Cocos and the Galapagos Islands, but the frequency of movements between the islands appears to be relatively
low (<7% of the tagged sharks). The most common depth at which the sharks swam coincided with the thermocline (rs = 0.72, p < 0.01). The depth of the thermocline varied depending on the time of the year. Nocturnal detections of the sharks were more
frequent during the cold season than during the warm season (W = 60, p < 0.01). We also found that hammerheads spent significantly more time on the up-current side of the island (Kruskal-Wallis = 31.1008;
p < 0.01). This study contributes to the knowledge of hammerhead sharks not only in Malpelo Island but also at a regional level
in the Eastern Tropical Pacific. 相似文献
9.
Dennis Hasselquist ?rjan ?stman Jonas Waldenstr?m Staffan Bensch 《Journal of Ornithology》2007,148(4):401-409
We studied the prevalence and intensity of the haemosporidian blood parasite Haemoproteus payevskyi in great reed warblers at Lake Kvismaren (6 years) and Lake Segersj? (3 years) in Sweden. Based on microscopic inspection
of slides from 282 adult birds, 20.6% showed infection of H. payevskyi in circulating red blood cells in at least 1 year. For parasite prevalence, there was no difference between years, sex, and
age classes. However, parasite intensity was higher in females than in males, and this was most pronounced in 1-year-old birds.
Individuals scored to carry parasites in year
n
were more likely to show parasite infection year
n + 1 than birds scored to be parasite-free in year
n
. None of 99 juvenile birds examined at the breeding site in late summer, 4–9 weeks after hatching, showed infection of H. payevskyi. Parasite intensity in infected adult birds decreased in the course of the breeding season and no new or relapse infections
were observed during this period. Thus, our data imply that in the great reed warbler, a long-distance migrant to tropical
Africa, transmission of H. payevskyi occurs on wintering sites or at stopover sites during migration. 相似文献
10.
Sandra Díaz-Sánchez Ainhoa Mateo Moriones Fabián Casas Ursula H?fle 《European Journal of Wildlife Research》2012,58(1):99-105
For hunting purposes, several millions of red-legged partridges (Alectoris rufa) are released each year in Spain, and these releases have the potential to introduce new parasites and disease into wild
populations. We studied the prevalence of Escherichia coli, Campylobacter sp. and Salmonella sp. in the intestinal flora of red-legged partridges from three different husbandry groups: farm-reared, restocked and natural
populations. Prevalence of E. coli was significantly higher in farm-reared (45%, p = 0.01) and restocked partridges (60%, p < 0.001) than in wild ones (6%, p > 0.05). The prevalence of Campylobacter sp. (23%, 100 out of 444) did not differ significantly between these three husbandry groups, and Salmonella sp. was only detected in a group of partridge chicks on one of the farms studied (0.9%, 5 out of 544). These results suggest
that farm-reared and restocked partridges can act as carriers of these three enteropathogens and highlight a potential risk
of transmission to natural populations via the releases of farm-reared partridges. However, future investigations are needed
regarding the relation of the isolated bacteria with zoonotic strains and dissemination of antibiotic resistant microorganisms,
especially E. coli, and to better evaluate the effect that these three enteropathogens have on partridge health and on the success of restocking
with farm-reared birds. 相似文献
11.
A. L. Brochet M. Gauthier-Clerc M. Guillemain H. Fritz A. Waterkeyn á. Baltanás A. J. Green 《Hydrobiologia》2010,637(1):255-261
Invertebrate propagules may survive internal and external transports by waterbirds, thus facilitating their dispersal between
aquatic habitats. However, field data on such transport remain limited, especially for exozoochory. We quantified and compared
the rates of internal and external invertebrate transports simultaneously in a wintering population of teal (Anas crecca) in the Camargue (southern France). We inspected lower gut (rectum) contents of birds that had been shot (N = 366) and washed birds that had been live-trapped (N = 68) during the winters 2006–2007 and 2007–2008. At least one propagule was recorded in 2.5% and 10.3% of internal and external
samples, respectively. Cladoceran, ostracod, plumatellid bryozoan and anostracan propagules were all recorded in both internal
and external samples. Hatching confirmed their viability, except for anostracan eggs. At least three cladoceran species and
two ostracod species were recorded, none of which had previously been shown to be dispersed by birds. Amongst external samples,
we recorded a significant seasonal trend in 1 year with most propagules recorded before December, keeping with a seasonal
decline in the availability of propagules on the water surface. This study provides evidence that teal may be important vectors
of invertebrate dispersal both within the Camargue and along migratory flyways. 相似文献
12.
We observed a group of capped langurs for 12 mo in the Pakhui Wildlife Sanctuary, Arunachal Pradesh, India. We recorded the
time of feeding on different food plant species, food categories, and the feeding heights of monkeys in trees. Capped langurs
spent 68% of their feeding time on leaves, 16% on flowers, and 16% on fruits. Feeding on leaves was consistently high (p < 0.01) during the year, with the highest feeding in May (85%) and the lowest in January (47%). The seasonal difference in
feeding on leaves is significant (p < 0.05): it was higher in summer and during monsoon. The feeding time on flowers was maximal (35%) in March and that on fruits
and seeds was minimal (38%) in January. Langurs ate 52 plant species throughout the year. The largest number of plants (6)
were species of Moraceae, and langurs spent more feeding time (20%) on them alone. The number of plants eaten per month varied
significantly (p < 0.05). Langurs ate Gmelina arborea, Albizzia lucida, Ficus glomereta, and Makania micrantha throughout the year. They spent 44% of their feeding time in terminal canopies and their average feeding height was 30–35 m.
This is the first study to examine the feeding ecology of capped langurs and provides baseline data for the species. 相似文献
13.
A new method to measure and quantify human disturbance in seabirds is presented. The stomach temperatures of moulting emperor
penguin chicks and adults (Aptenodytes forsteri) were recorded continuously using temperature loggers while the birds were exposed to various man-induced stimuli. Stimuli
resulted in typical temperature rises that varied with the duration and strength of the stimulus. On average, the temperature
rose by 1.5 K, the maximum reached being 2.6 K following a stimulus of more than 2 h duration. Minimal energy costs inducing
the temperature rises could be estimated. Depending on the intensity of disturbance, minimal energy expenditure ranged between
3.2 kJ/kg and 9.7 kJ/kg, being slightly higher in chicks. This represented up to 10% of the daily energy demand during moult.
The estimated minimal increase in metabolic rate during stress averaged 2.3 W/kg in chicks and 2.0 W/kg in adults (maxima
of 4.2 W/kg and 3.3 W/kg, respectively).
Received: 12 September 1996 / Accepted: 5 March 1997 相似文献
14.
Segalés J Valero O Espinal A López-Soria S Nofrarías M Calsamiglia M Sibila M 《International journal of biometeorology》2012,56(6):1167-1171
The objective of the present work was to elucidate the potential relationship between Mycoplasma hyopneumoniae infection and seroconversion dynamics and climatological conditions in four groups of pigs from the same farm born in different seasons of the year. Nasal swabs and blood samples were taken from 184 pigs at 1, 3, 6, 9, 12, 15, 18, 22 and 25 (slaughter age) weeks of age. Outside climatologic parameters, including temperature (°C), relative humidity (%), precipitation (l/m2) and wind speed (m/s) were recorded weekly from January 2003 to June 2004. Percentage of nPCR detection of M. hyopneumoniae in nasal swabs was associated significantly with the weekly precipitation rate [P = 0.0018, OR = 1.31 (IC = 1.11–1.55)]; the higher the precipitation rate, the higher the probability of being M. hyopneumoniae nPCR-positive. On the other hand, the percentage of seropositive pigs had a significant association with mean weekly temperature rate [P = 0.0012, OR = 0.89 [IC = 0.84–0.95]); the lower the temperature, the higher the probability of being M. hyopneumoniae seropositive. Animals born in autumn (when higher precipitations rates were recorded), entering finishing units in winter (when lower temperatures were recorded), and reaching slaughter in spring, had the highest probability of being infected by M. hyopneumoniae and the highest probability of being M. hyopneumoniae seropositive. 相似文献
15.
Christian Pietri Paulo Célio Alves José Melo-Ferreira 《European Journal of Wildlife Research》2011,57(2):313-321
The Italian hare, Lepus corsicanus, was first described in Corsica more than 100 years ago, but the knowledge on the status of the species in this island remains
scarce. Moreover, frequent introductions of thousands of individuals from other hare species, namely Lepus europaeus and Lepus granatensis, into Corsica are known to have occurred and an updated assessment of the prevalence of L. corsicanus in Corsica is therefore of utmost importance. Here, to estimate the relative prevalence of the hare species present in Corsica,
we conducted a molecular analysis on 67 samples collected by hunters between 2002 and 2007 in 36 Corsican communes. Sequencing
of portions of the nuclear gene transferrin and of the control region of the mitochondrial DNA allowed classifying most of
the collected samples as belonging to L. corsicanus (70.1%). Of the sampled Corsican communes, 86.1% contained this species, while only in 11.1%, L. europaeus was present. Three of the analyzed specimens showed an inconsistent molecular assignment between markers suggesting a hybrid
origin: L. corsicanus × L. europaeus, L. corsicanus × L. granatensis, and L. europaeus × L. granatensis. The first two cases of hybridization had never been described in nature, even in studies focusing on hares from Italy where
L. corsicanus and L. europaeus are often sympatric. These results stress the real risk of corrosion of the native gene pool of L. corsicanus via hybridization with introduced species. We highlight the need of urgently rethinking the management plan of hare populations
in Corsica. 相似文献
16.
Omaima Abou-Shady Mona S El Raziky Mayssa Mohamed Zaki Reham Kamal Mohamed 《Biological trace element research》2011,140(1):1-6
The aim of this study is to evaluate the serological levels of zinc, copper and iron in Giardia lamblia-infected children and to study the effect of giardiasis on their weight compared to controls. We studied 30 children, 1–10 years
old, who attended the outpatient clinics of Cairo university pediatric hospital, with gastrointestinal complaints and diagnosed
as having giardiasis by stools examination, they were enrolled as a study group. The control group consisted of 30 age- and
sex-matched healthy children, free of gastrointestinal complaints and free of giardiasis. Serological levels of zinc, copper,
and iron were measured by atomic absorption spectrophotometer. The infected group had significantly lower weight, serum iron,
and zinc than controls (P = 0.035, <0.001, and <0.001 respectively) and 63.3% of patients infected with giardiasis were 1–5 years old. In the infected
cases, 60% suffered from of abdominal pain, 50% from weight loss, and 40% had intermittent diarrhea. Infected cases with weight
percentiles below the fifth had significantly lower serum iron than those with normal percentiles (>5th). In conclusion, most
giardiasis-infected children were between 1 and 5 years, with significant affection of weight, abdominal pain, and/or intermittent
diarrhea. Serum zinc and iron levels were significantly decreased in the infected group compared to control (P < 0.001). 相似文献
17.
The effects of elevated CO2 on plant biomass and community structure have been studied for four seasons in a calcareous grassland in northwest Switzerland.
This highly diverse, semi-natural plant community is dominated by the perennial grass Bromus erectus and is mown twice a year to maintain species composition. Plots of 1.3 m2 were exposed to ambient or elevated CO2 concentrations (n = 8) using a novel CO2 exposure technique, screen-aided CO2 control (SACC) starting in March 1994. In the 1st year of treatment, the annual harvested biomass (sum of aboveground biomass
from mowings in June and October) was not significantly affected by elevated CO2. However, biomass increased significantly at elevated CO2 in the 2nd (+20%, P = 0.05), 3rd (+21%, P = 0.02) and 4th years (+29%, P = 0.02). There were no detectable differences in root biomass in the top 8 cm of soil between CO2 treatments on eight out of nine sampling dates. There were significant differences in CO2 responsiveness between functional groups (legumes, non-leguminous forbs, graminoids) in the 2nd (P = 0.07) and 3rd (P < 0.001) years of the study. The order of CO2 responsiveness among functional groups changed substantially from the 2nd to the 3rd year; for example, non-leguminous forbs
had the smallest relative response in the 2nd year and the largest in the 3rd year. By the 3rd year of CO2 exposure, large species-specific differences in CO2 response had developed. For five important species or genera the order of responsiveness was Lotus corniculatus (+271%), Carex flacca (+249%), Bromus erectus (+33%), Sanguisorba minor (no significant CO2 effect), and six Trifolium species (a negative response that was not significant). The positive CO2 responses in Bromus and Carex were most closely related to increases in tiller number. Species richness was not affected by CO2 treatment, but species evenness increased under elevated CO2 (modified Hill ratio; P = 0.03) in June of the 3rd year, resulting in a marginally significant increase in species diversity (Simpson's index; P = 0.09). This and other experiments with calcareous grassland plants show that elevated atmospheric CO2 concentrations can substantially alter the structure of calcareous grassland communities and may increase plant community
biomass.
Received: 12 July 1997 / Accepted: 14 September 1998 相似文献
18.
Y. Winter O. von Helversen 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1998,168(2):105-111
Flapping flight is one of the most expensive activities in terms of metabolic cost and this cost has previously been considered
equal for the two extant vertebrate groups which evolved flapping flight. Owing to the difficulty of obtaining accurate measurements
without disturbing flight performance, current estimates of flight cost within the group of small birds and bats differ by
more than a factor of five for given body masses. To minimize the potential problem that flight behaviour may be affected
by the measurements, we developed an indirect method of measuring flight energy expenditure based on time budget analysis
in which small nectar-feeding bats (Glossophaginae) could continue their natural rhythm of flying and resting entirely undisturbed.
Estimates of metabolic flight power based on 172 24-h time and energy budget measurements were obtained for nine individual
bats from six species (mass 7–28 g). Metabolic flight power (PF) of small bats was found to increase with body mass following the relation PF = 50.2 M0.771 (r2 = 0.96, n = 13, PF in W, M in kg). This is about 20–25% below the majority of current predictions of metabolic flight cost for small birds.
Thus, either the flight cost of small birds is significantly lower than has previously been thought or, contrary to current
opinion, small bats require less energy to fly than birds.
Accepted: 29 September 1997 相似文献
19.
K. M. Pagenkopp J. Klicka K. L. Durrant J. C. Garvin R. C. Fleischer 《Conservation Genetics》2008,9(6):1577-1588
Our current understanding of migration routes of many birds is limited and researchers have employed various methods to determine
migratory patterns. Recently, parasites have been used to track migratory birds. The objective of this study was to determine
whether haemosporidian parasite lineages detect significant geographic structure in common yellowthroats (Geothlypis trichas). We examined liver tissue or blood from 552 birds sampled from multiple locations throughout the continental United States,
southern Canada, and the Bahamas. We found a 52.7% overall prevalence of haematozoan infection. We identified 86.1% of these
infections to genus: 81% were Plasmodium; 5% were Haemoproteus; and 0.1% were Leucocytozoon. There were significant differences in the prevalence of different parasite genera among regions (χ2 = 36.82, P < 0.0001) and in the proportion of Plasmodium infections versus other parasites among regions (χ2 = 35.52, P < 0.0001). Sequence information identified three Haemoproteus lineages, two Leucocytozoon lineages, and thirteen Plasmodium lineages. Due to the low number of Haemoproteus and Leucocytozoon, only Plasmodium lineages were used in the geographic comparison of lineages. Six Plasmodium lineages were found in eight or more birds and the prevalence of these varied significantly among regions (χ2 = 172.33, P < 0.0001). Additionally, 45 juvenile birds were sampled to determine what parasites could be obtained in the breeding grounds
and we found only one lineage. In conclusion, parasite lineages show some geographic structure, with some lineages being more
geographically specific than others, but are not useful for determining migratory connectivity in this species.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
The U.S. Government’s right to retain a non-exclusive, royalty-free license in and to any copyright is acknowledged. 相似文献
20.
We studied the possible role of resource limitation and interspecific competition in assemblages of dabbling ducks on breeding
lakes in Finland and Sweden with observational and experimental data. After initial vegetation mapping and yearly censuses
of ducks in 1985–1990, we collected observational data in 1991–1994 from 28 lakes with natural populations of mallard Anas platyrhynchos and teal A. crecca. Mallard and teal co-occur over vast areas in the Holarctic and they are the only breeding dabbling ducks on many oligotrophic
lakes. Both species are migratory in our study regions, teal arriving later in spring than mallards. Log-linear model analysis
of observational presence/absence data revealed a positive, not a negative, association between the species. This association
was independent of habitat diversity as well as of lake size. Mallard-teal interaction was also studied in a cross-over introduction
experiment in 32 other lakes in two years. Wing-clipped mallards were introduced to breeding lakes before the arrival of teal
to induce resource limitation and interspecific competition, hypothesized to reduce lake use by teal. The density of mallard
pairs on experimental lakes was 2.9–8.0 times higher than on controls, but there was no negative response by teal to the treatment.
This is the first combined observational-experimental demonstration of lack of interspecific competition in waterfowl. Our
results indicate that heterospecific attraction may affect species co-existence in dabbling ducks.
Received: 28 October 1996 / Accepted: 13 January 1997 相似文献