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Dispersal by frugivorous birds facilitates invasion by many exotic plants. We measured the seed rain of ornithochorous native and exotic plants at three habitats of a fragmented landscape of the northeastern United States for 1 year. We studied maple-beech forests, old fields, and abandoned conifer plantations. Across all sites we collected 2,196 ornithochorous seeds, including seeds from six exotic species and 10 native species. The majority (90%) of collected seeds were from exotic species. Seed dispersal was broadly similar among habitats, though seed rain of exotic species was higher in old fields than forested habitats. Seed rain was not strongly influenced by artificial perches for most species. However, seeds of exotic species were more commonly found in traps under an artificial perch in old fields. Seed rains for the exotic Elaeagnus umbellata, Rhamnus cathartica, and Rosa multiflora were positively associated with local density of mature plants. Seed rain of R. cathartica was positively associated with abundance of seedlings but not saplings, suggesting that post-dispersal mortality was important. Seed dispersal of the exotic Lonicera spp. was high in all habitats, accounting for 66% of all seeds collected. With the exception of Lonicera spp., seed rain of common exotic invaders was affected by the abundance of seed sources, and these species might be effectively controlled by elimination of local fruiting plants. Fruits of Lonicera morrowii, which has extensively invaded our area, are apparently a common component in the diet of frugivores.  相似文献   

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Paleontological and molecular data suggest that the divergence of the European and Asian badgers (Meles meles and Meles leucurus, respectively) from their ancestor Meles thorali might have taken place in the Middle to Late Villafranchian boundary (ca. 1.8 Ma). However, the available record of Late Villafrachian European badgers is scanty and poorly known, and this hypothesis needs more paleontological data in order to be tested. The badger hemimandible from the Iberian locality of Fuente Nueva 3, a locality placed in the beginning of the Late Villafranchian, supports the idea of an early divergence between European and Asian badgers.  相似文献   

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To measure farmed foxes’ motivations for full, naturalistic social contact, we constructed an apparatus where they could perform an operant to access stimuli, but then leave freely and thence determine their own bout lengths. Motivational measures based on demand curves can be invalid in such set-ups, and we therefore sought to validate the measure ‘maximum price paid’. This was achieved by measuring six silver fox males’ maximum operant responding for access or proximity to three resources differing in biological significance: food, vixens in oestrus and males. We predicted that if valid, maximum price paid would be highest for food and vixens. Maximum price were 970 ± 399 (S.E.) for food, 677 ± 173 (S.E.) for vixens and 389 ± 101 (S.E.) for other males (P < 0.05). In contrast, our complementary measures of motivation – price elasticity, expenditure and consumer surplus – did not differentiate between the resources, and ranked them in different orders (albeit not significantly). This was because the foxes rescheduled their behaviour with increasing costs, decreasing bout number while increasing bout length, to different extents with the three resources. Additional findings showed that all subjects ‘overpaid’, performing the operant response more than was required. This increased as the costs increased, perhaps due to increasing ‘time outs’ on the time-restricted schedule (DRH) as the task got harder. However, the overpayment was also highest when males were the resource, suggesting that operant responding was slowest and least efficient when working for less-valued resources. The resources present also affected how the foxes used the rest of the apparatus and influenced their behaviour; subjects staying more in the operant compartment when the resource was social (especially a female), but retreating to a distant compartment when it was food. While proximity to oestrous vixens elicited higher levels of tail wagging and only low levels of pacing, indicating a positive motivation, proximity to males elicited relatively high levels of pacing plus agonistic gaping, suggesting that the motives for seeking contact with males related to aggression. Thus, although our operant set-up reveals a drive to approach other males, the possible aggressive motives suggest that this sort of social contact would not necessarily improve their welfare in a traditional housing system. Overall, these results help improve the design and interpretation of preference tests, and confirm maximum price paid as a useful motivational measure for farmed foxes.  相似文献   

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We characterized the diet of the Indian fox (Vulpes bengalensis) during the breeding season in a semi-desert region of Western India. Diet was estimated using scat analysis. We used Index of Relative Importance (IRI) to determine the contribution of prey items in the diet of the Indian fox.Indian foxes were observed to feed on a wide variety of prey items. Arthropods were the most frequently occurring prey in their diet. IRI scores were highest for the group Coleoptera and Orthoptera followed by rodents, termites, Ziziphus fruits and spiny tailed lizards (Uromastyx hardwickii). IRI scores for rodents were higher for pups, differing significantly from proportions present in adult diet, thus indicating that they are crucial food items for the young ones. Prey proportions in the fox diet differed between the two habitats in the study area (grassland and scrubland).Our data suggest that the Indian fox is essentially an omnivore showing similar diet (in terms of high incidence of arthropods) to foxes inhabiting arid and semi-arid regions. The opportunistic and generalist strategy has probably helped the species to survive in varied habitats across the Indian subcontinent.  相似文献   

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Habitat fragmentation can lead to substantial genetic depletion. As a consequence, restoration schemes often involve the introduction of propagules into isolated plant populations to improve genetic diversity. To avoid introducing maladapted seed material, such measures need to account for landscape genetic processes. However, surprisingly little is known as to whether different species within a distinct fragmented ecosystem respond similarly or idiosyncratically to eco-geographical variation.Using AFLP markers, we studied the population genetic structure in three species of the highly fragmented Kulunda steppe (South Siberia): Adonis villosa, Jurinea multiflora and Paeonia hybrida. In each population, we conducted a vegetation survey. We performed Mantel tests and an RDA approach to investigate how genetic structure was affected by three spatio-environmental variables: spatial distance, floristic composition and climate.Despite strong fragmentation, genetic diversity was moderate (A. villosa, J. multiflora) to high (P. hybrida), while differentiation was weak (A. villosa) to moderate (P. hybrida, J. multiflora). Mantel tests showed that spatial distance correlated with genetic distance in A. villosa and P. hybrida. Floristic composition was significantly associated with genetic differentiation in A. villosa. Climate did not have an effect on genetic structure in any species.All three species are long-lived, which may contribute to explaining why genetic effects of recent fragmentation are still limited. We highlight that floristic composition can be a powerful predictor of population differentiation in species that show rather stable conditions in their recent population histories (e.g. A. villosa). This can have important implications for identifying source populations where restoration actions involve the (re)introduction of propagules. In contrast, for P. hybrida and J. multiflora, we could not identify deterministic drivers of differentiation. We advocate that future studies should aim at disentangling the interactive effects of varying life cycles, eco-evolutionary population histories and spatio-environmental heterogeneity in fragmented landscapes.  相似文献   

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Vocal individuality has been documented in a variety of mammalian species and it has been proposed that this individuality can be used as a vocal fingerprint to monitor individuals. Here we provide and test a classification method using Mel-frequency cepstral coefficients (MFCCs) to extract features from Bornean gibbon female calls. Our method is semi-automated as it requires manual pre-processing to identify and extract calls from the original recordings. We compared two methods of MFCC feature extraction: (1) averaging across all time windows and (2) creating a standardized number of time windows for each call. We analysed 376 calls from 33 gibbon females and, using linear discriminant analysis, found that we were able to improve female identification accuracy from 95.7% with spectrogram features to 98.4% accuracy when averaging MFCCs across time windows, and 98.9% accuracy when using a standardized number of windows. We divided our data randomly into training and test data-sets, and tested the accuracy of support vector machine (SVM) predictions over 100 iterations. We found that we could predict female identity in the test data-set with a 98.8% accuracy. Using SVM on our entire data-set, we were able to predict female identity with 99.5% accuracy (validated by leave-one-out cross-validation). Lastly, we used the method presented here to classify four females recorded during three or more recording seasons using SVM with limited success. We provide evidence that MFCC feature extraction is effective for distinguishing between female Bornean gibbons, and make suggestions for future vocal fingerprinting applications.  相似文献   

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Ectoparasitism in bats seems to be influenced strongly by the type of roost preferred by the hosts, and group size; however, the effect of habitat loss and fragmentation on the prevalence of ectoparasites in bats has scarcely been studied. In northeastern Yucatan, Mexico, we estimated the prevalence of infestation by Streblidae flies in three phyllostomid bat species with different roost preferences (caves, trees, or both) in two types of landscape matrices (tropical semi‐deciduous forest and man‐made pastures) that differed in area of forest cover and the number of forest fragments. Habitat fragmentation and the presence of a contrasting matrix may limit the availability of roosts (trees) and the movement of bats across the landscape. Accordingly, we hypothesized higher prevalence of Streblidae infestation in the pasture matrix and in the group of bats that roost in trees. Bat abundance was higher in the pasture matrix; however, the prevalence of infestation was significantly higher in the continuous forest matrix and in bats that roosted in caves. The prevalence of some species of Streblidae was affected by habitat fragmentation in species that roost in caves, such as Desmodus rotundus, as well as those using foliage and caves, such as Artibeus jamaicensis. Our results provide evidence that some species of Streblidae may respond differently to habitat fragmentation than their hosts, generating changes to bat‐ectoparasite interactions in fragmented areas. Environmental variations involving roosts, not evaluated in this study, may influence our results, since these factors affect ectoparasite abundance and reproduction.  相似文献   

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Male songbirds often move off-territory to pursue extra-pair fertilizations. This movement represents a trade-off between paternity gain and loss and can be influenced by male quality and access to fertile females. Access to females could be reduced in fragmented landscapes that have small patches and low connectedness. We studied movement and extra-pair fertilization success of radio-tracked male American Redstarts (Setophaga ruticilla) in forest patches in an agricultural landscape in Alberta, Canada, over 2 years. Males spent an average of 18% of their time off-territory, mostly intruding onto adjacent territories and rarely moving between patches. They averaged 0.8 trips/h, with mean trip duration of 17 min and mean trip distance of 104 m. Less time was spent off-territory when their mate was nest-building and males intruded most often onto territories with nest-building females. Males with higher song rates and more nearby females intruded most onto other territories. Monogamous males in better condition with higher song rates spent the most time off-territory. However, males with more nearby females and higher local breeding synchrony spent the least time off-territory, suggesting these males face a trade-off between seeking extra-pair fertilizations and protecting against cuckoldry. Forest cover was not an important predictor of movement. Investment in off-territory movement did not predict extra-pair fertilization success or probability of cuckoldry. However, few tracked males achieved extra-pair fertilizations (1/22 tracked males vs 18/57 non-tracked males), possibly an artefact of low sample size or the effect of radio transmitters on female choice.  相似文献   

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Disa cardinalis and three populations within the D. tripetaloides species complex contain variation in their chloroplast DNA (cpDNA) variability. All four taxa possessed unique cpDNAs and sequence divergence values ranged from 0.34 to 1.03%. A phylogeny of these genomes was reconstructed, along with the genomes of three other species, D. racemosa, D. uniflora and D. venosa, all of which are also section Disa and series RAcemosae, to determine the relationship of these closely related species to the D. tripetaloides complex. A phylogeny of the taxa using morphological data was also reconstructed. Outgroup comparison was made with D. sagittalis, a member of section Coryphaea. Although the molecular and morphological data were not completely congruent, both data types revealed D. cardinalis, rather than D. tripetaloides ssp. aurata, to be more closely allied with D. tripetaloides ssp. tripetaloides, suggesting that D. tripetaloides ssp. aurata should be elevated to species rank. Additionally, the high sequence divergence observed between the Natal and Cape populations, coupled with their geographical isolation and alternate flowering seasons, suggests that these two D. tripetaloides ssp. tripetaloides populations may, in fact, be more appropriately ranked as subspecies.  相似文献   

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Terrestrial isopods were collected in 13 forest fragments differing in area (within the range of 0.1 and 254.5 ha), shape and composition of forest vegetation (thermophilous oak, mesophilous oak-hornbeam, thermophilous oak-hornbeam, acidophilous oak, basiphilous oak, beech oak-hornbeam, moist mixed deciduous forest, plantations of deciduous and coniferous trees), all situated in the Český kras Protected Landscape Area, Czech Republic, Central Europe. Number of sites sampled in each fragment of forest depended on its size and ranged from 1 to 7. Altogether 30 sites were sampled. Soil samples (5 per site collected twice a year) and pitfall trapping (5 traps per site in continuous operation throughout a year) during 2008–2009 yielded a total of 14 species of terrestrial isopods. The highest densities and highest epigeic activities of terrestrial isopods were recorded in the smallest fragments of woodland. Although a wider range of habitats were sampled in the larger fragments of woodland there was not a greater diversity of species there and the population densities and epigeic activities recorded there were lower. Porcellium collicola was most abundant in small fragments of woodland regardless the vegetation there. Armadillidium vulgare and Protracheoniscus politus were statistically more abundant in the larger fragments of woodland. The results indicate that forest fragmentation does not necessarily result in a decrease in the species richness of the isopod assemblages in such habitats.  相似文献   

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Little is known about the population characteristics of Alouatta pigra under conditions of forest fragmentation-information that is important to understanding its tolerance to habitat loss. In this work we present data on forest loss and on troop size, age, and sex composition for a population of black howler monkeys existing in the fragmented landscape surrounding the Mayan site of Palenque, Chiapas, Mexico. Two aerial photos (1:70,000) of the study area (261 km(2)) taken in 1984 and 2001 were examined to assess forest loss. Between June and December 2001 and January and March 2002 we surveyed 44 forest fragments for the presence of howler monkeys. Examination of aerial photos showed that 33% of the forest present in 1984 had disappeared by 2001, and detected an increment in the number of forest fragments present in the landscape. We discovered a total of 115 howler monkeys living in 22 of the 44 forest fragments studied, of which 107 were members of 18 troops. The rest were solitary males or small groups of males living in isolated forest fragments. Troop size ranged from two to 15 individuals (mean 5.9+3.0 ind). 31% and 15% of individuals in the troops were juveniles and infants, respectively, suggesting continued reproductive activity. Howler monkey troops in the forest fragments were on average smaller (5.9+/-3.0 ind) than troops in the nearby protected forest of the Mayan site (7.0+/-2.8 ind). The mean density of howlers in the forest fragments was 119+/-82.9 ind/km(2). The establishment of corridors is suggested as a possible conservation scenario for the fragmented howler population investigated, and as a conservation measure to connect this population with the howler population found in the protected forest of the Mayan site.  相似文献   

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Knowledge of threatened species’ distributions is essential for effective conservation decision‐making. Species distribution models (SDMs) are widely used to map species’ geographic ranges, identify new areas of suitable habitat and guide field surveys. In New South Wales (NSW), Australia, there are grave doubts about whether populations of the critically endangered long‐footed potoroo (Potorous longipes) remain extant, and identification of occupied sites is a high priority for its conservation. We used an SDM (Maxent) to identify regions in NSW that may have suitable habitat for the potoroo. The SDM was built with seven climate layers and had strong predictive performance (cross‐validated AUC = 0.94). We then combined this information on habitat suitability with vegetation and topography, to identify 58 survey sites across NSW. From April 2016 to May 2017, we undertook six field trips deploying six to eight cameras at each site for 52–63 days, resulting in 25 120 camera trap nights. A total of 215 759 images captured 43 native and feral animal species, but no long‐footed potoroos. Following the survey, newly available, independent presence and absence data were used to validate our model. A Kruskal–Wallis H test indicated that habitat suitability values were significantly higher at presence locations than absence locations (H = 58.66, d.f. = 1, P < 0.001). Finally, we refitted the Maxent model with the new data and identified additional regions that future surveys could explore. We conclude, however, that if the long‐footed potoroo remains extant in NSW, it is extremely rare.  相似文献   

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The bumblebee fauna of the North of European Russia includes 34 species. The trends in bumblebee diversity within the region are characterized. The species richness is the greatest in the middle taiga subzone and decreases from south to north, reaching its minimum in the Arctic tundra. Based on analysis of the zonal differentiation of bumblebee species, only four of them were found to be true arctic forms: Bombus (Alpinobombus) polaris, B. (Al.) balteatus, B. (Al.) hyperboreus, and B. (Pr.) lapponicus glacialis, whereas the rest belong to the temperate, boreal, and subboreal groups.  相似文献   

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A. Salda?a  E. Gianoli  C. H. Lusk 《Oecologia》2005,145(2):251-256
In Chilean evergreen temperate forest, fern species of the genus Blechnum occur in diverse microhabitats ranging from large gaps to heavily shaded understoreys. We hypothesised that differences in the ecological breadth of three co-occurring Blechnum species would be associated with differences in magnitude of ecophysiological responses to light availability. We quantified the field distribution of each species in relation to diffuse light availability (% canopy openness), and measured in situ variation in photosynthetic capacity (A), dark respiration (R d) and specific leaf area (SLA) across the light gradient. The response of SLA of each species was also evaluated in a common garden in two light conditions (understorey and forest edge). The three Blechnum species differed significantly in the range of light environments occupied (breadth: B. chilense > B. hastatum > B. mochaenum). Despite significant interspecific differences in average A and R d, the response of these traits to light availability did not differ among species. However, there was significant interspecific variation in both the mean value and the plasticity of SLA to light availability, the species with least ecological breadth (B. mochaenum) showing a flatter reaction norm (lower response) than its two congeners. This pattern was also found in the common garden experiment. The adjustment of leaf morphology (SLA) to light availability appears to be an important mechanism of acclimation in these Blechnum species. The narrow range of light environments occupied by B. mochaenum may be at least partly attributable to its inability to display phenotypic plasticity in SLA to changes in light availability.  相似文献   

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This paper examines a cryptic species complex comprising three nominal bee species: Colletes halophilus, Colletes hederae, and Colletes succinctus. Multiple individuals of each were sequenced for four gene fragments: mitochondrial cytochrome oxidase 1 (CO-1), internal transcribed spacer 2 (ITS-2) and flanking regions, elongation factor 1 alpha (EF-1α), and 28S. In addition, the distribution patterns and phenology of all species were examined. Fixed substitutions distinguishing the three species are present in EF-1α and ITS-2. Their distribution patterns differ clearly: Colletes halophilus is endemic to coastal habitats of the southern North Sea and the English Channel; Colletes hederae occurs from Slovenia in the southeast to southern England in the northwest; the range of Colletes succinctus covers most of Europe and reaches western Kazakhstan. Where the three species occur jointly in western Europe, their flight activities differ significantly. The genetic distinctions and the differences in distribution, phenology and flower specialisation clearly support their status as distinct species.  相似文献   

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