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1.
Foraging distance is a key determinant of colony survival and pollination potential in bumblebees Bombus spp. However this aspect of bumblebee ecology is poorly understood because of the difficulty in locating colonies of these central place foragers. Here, we used a combination of molecular microsatellite analyses, remote sensing and spatial analyses using kernel density estimates to estimate nest location and foraging distances for a large number of wild colonies of two species, and related these to the distribution of foraging habitats across an experimentally manipulated landscape. Mean foraging distances were 755 m for Bombus lapidarius and 775 m for B. pascuorum (using our most conservative estimation method). Colony‐specific foraging distances of both species varied with landscape structure, decreasing as the proportion of foraging habitats increased. This is the first time that foraging distance in wild bumblebees has been shown to vary with resource availability. Our method offers a means of estimating foraging distances in social insects, and informs the scale of management required to conserve bumblebee populations and enhance their pollination services across different landscapes.  相似文献   

2.
Molecular methods have greatly increased our understanding of the previously cryptic spatial ecology of bumble bees (Bombus spp.), with knowledge of the spatial ecology of these bees being central to conserving their essential pollination services. Bombus hypnorum, the Tree Bumble Bee, is unusual in that it has recently rapidly expanded its range, having colonized much of the UK mainland since 2001. However, the spatial ecology of B. hypnorum has not previously been investigated. To address this issue, and to investigate whether specific features of the spatial ecology of B. hypnorum are associated with its rapid range expansion, we used 14 microsatellite markers to estimate worker foraging distance, nest density, between‐year lineage survival rate and isolation by distance in a representative UK B. hypnorum population. After assigning workers to colonies based on full or half sibship, we estimated the mean colony‐specific worker foraging distance as 103.6 m, considerably less than values reported from most other bumble bee populations. Estimated nest density was notably high (2.56 and 0.72 colonies ha?1 in 2014 and 2015, respectively), estimated between‐year lineage survival rate was 0.07, and there was no evidence of fine‐scale isolation by distance. In addition, genotyping stored sperm dissected from sampled queens confirmed polyandry in this population (mean minimum mating frequency of 1.7 males per queen). Overall, our findings establish critical spatial ecological parameters and the mating system of this unusual bumble bee population and suggest that short worker foraging distances and high nest densities are associated with its rapid range expansion.  相似文献   

3.
1. Bees are ecologically important pollinators that are threatened by disease, habitat degradation, and habitat loss. Bee species that share ecological traits (e.g. body size, diet breadth, and sociality) may often respond similarly to environmental disturbance; however, few studies have examined the extent to which closely related, ecologically similar species exhibit divergent responses to the same forms of disturbance. 2. In the present study, the responses of bumble bees (Apidae: genus Bombus) to urbanization are examined by combining field surveys with the quantification of local‐ and landscape‐level variables using Geographic Information Systems (GIS). During the spring and summer of 2012 and 2013, 57, bumble bees were surveyed in 1‐ha plots in San Diego County, California that spanned a gradient of urbanisation. Species‐level, occurrence (presence/absence) data and logistic regressions were then used to identify determinants of Bombus occurrence across this landscape. 3. Approximately 1000 Bombus individuals belonging to three species were observed: B. californicus Smith, B. melanopygus Cresson, and B. vosnesenskii Radoszkowski. The occurrence of all Bombus species was negatively related to impermeable surface cover within study plots, but species responded uniquely to other plot‐scale variables and exhibited distinctive patterns of scale‐dependency with respect to impermeable surface cover surrounding plots. 4. Urbanisation negatively affected all three focal bumble bee species in this study. Species‐specific responses to plot‐scale and landscape‐scale variables presumably reflect interspecific trait differences (e.g. body size, tongue length, and foraging behaviour). Unique responses to urbanisation caution against pooling species into functional groups based merely on taxonomic relationships or perceived ecological similarities.  相似文献   

4.
Genetic bottlenecks can limit the success of populations colonizing new ranges. However, successful colonizations can occur despite bottlenecks, a phenomenon known as the genetic paradox of invasion. Eusocial Hymenoptera such as bumblebees (Bombus spp.) should be particularly vulnerable to genetic bottlenecks, since homozygosity at the sex-determining locus leads to costly diploid male production (DMP). The Tree Bumblebee (Bombus hypnorum) has rapidly colonized the UK since 2001 and has been highlighted as exemplifying the genetic paradox of invasion. Using microsatellite genotyping, combined with the first genetic estimates of DMP in UK B. hypnorum, we tested two alternative genetic hypotheses (‘bottleneck’ and ‘gene flow’ hypotheses) for B. hypnorum''s colonization of the UK. We found that the UK population has not undergone a recent severe genetic bottleneck and exhibits levels of genetic diversity falling between those of widespread and range-restricted Bombus species. Diploid males occurred in 15.4% of reared colonies, leading to an estimate of 21.5 alleles at the sex-determining locus. Overall, the findings show that this population is not bottlenecked, instead suggesting that it is experiencing continued gene flow from the continental European source population with only moderate loss of genetic diversity, and does not exemplify the genetic paradox of invasion.  相似文献   

5.
Changes in agricultural practice across Europe and North America have been associated with range contractions and local extinction of bumblebees (Bombus spp.). A number of agri‐environment schemes have been implemented to halt and reverse these declines, predominantly revolving around the provision of additional forage plants. Although it has been demonstrated that these schemes can attract substantial numbers of foraging bumblebees, it remains unclear to what extent they actually increase bumblebee populations. We used standardized transect walks and molecular techniques to compare the size of bumblebee populations between Higher Level Stewardship (HLS) farms implementing pollinator‐friendly schemes and Entry Level Stewardship (ELS) control farms. Bumblebee abundance on the transect walks was significantly higher on HLS farms than ELS farms. Molecular analysis suggested maximum foraging ranges of 566 m for Bombus hortorum, 714 m for B. lapidarius, 363 m for B. pascuorum and 799 m for B. terrestris. Substantial differences in maximum foraging range were found within bumblebee species between farm types. Accounting for foraging range differences, B. hortorum (47 vs 13 nests/km2) and B. lapidarius (45 vs 22 nests/km2) were found to nest at significantly greater densities on HLS farms than ELS farms. There were no significant differences between farm type for B. terrestris (88 vs 38 nests/km2) and B. pascuorum (32 vs 39 nests/km2). Across all bumblebee species, HLS management had a significantly positive effect on bumblebee nest density. These results show that targeted agri‐environment schemes that increase the availability of suitable forage can significantly increase the size of wild bumblebee populations.  相似文献   

6.
Wildlife-friendly management practices promote pollinators and pollination services in agricultural landscapes. Wild bee densities are driven by landscape composition, as they benefit from an increased availability of nesting and foraging resources at landscape scale. However, effects of landscape composition on bee foraging decisions and consequences for crop pollination have rarely been studied. We investigated, how landscape composition affects bee densities and foraging behavior in faba bean (Vicia faba L.) fields and how this impacts faba bean yield. We recorded densities and nectar robbing behavior of honeybees, long- tongued and short-tongued bumblebees in faba bean fields in eleven landscapes with varying landscape composition (e.g. land cover of oilseed rape, faba bean and semi-natural habitats). Moreover, we assessed yield components of faba beans via pollinator exclusion experiments. Increasing covers of faba bean and semi-natural habitats positively influenced bumblebee densities, while high oilseed rape covers negatively affected short-tongued bumblebee densities in bean fields. Increased faba bean covers enhanced the proportion of nectar-robbing short-tongued bumblebees. The number of beans per pod was increased by insect pollination, while the number of pods was decreased; these effects however depended on variety. Landscape composition interacted with bee densities in shaping yield components in V. faba. Our study emphasizes the importance of considering landscape management to maximize crop yields, as shown for the case of faba beans. The composition of agricultural landscape can modulate bee densities in crop fields, bees foraging behavior and pollination services.  相似文献   

7.
We used live-trapping and foraging to test for the effect of habitat selection and diet on structuring a community of six small mammals and one bird within the Soutpansberg, South Africa. We established grids that straddled adjacent habitats: woodland, rocky hillside, and grassland. Trapping and foraging were used to estimate abundance, habitat use, and species-specific foraging costs. The species with the highest abundance and foraging activity in a habitat, activity time, or food was considered the most efficient and presumed to have a competitive advantage. All species exhibited distinct patterns of spatial and temporal habitat preference which provided the main mechanism of coexistence, followed by diet selection. The study species were organized into three assemblages (α diversity): grassland, Rhabdomys pumilio, Dendromus melanotis, and Mus minutoides.; woodland, Aethomys ineptus and Micaelamys namaquensis; and rock-dwelling, M. namaquensis and Elephantulus myurus. Francolinus natalensis foraged in open rocky areas and under wooded islands within the grassland. Species organization across the habitats suggested that feeding opportunities are available within all habitats; however, distinct habitat preferences resulted from differing foraging aptitudes and efficiencies of the competing species. At Lajuma, species distribution and coexistence are promoted through distinct habitat preferences that were shaped by competition and species-specific foraging costs. The combination of trapping and foraging provided a mechanistic approach that integrates behavior into community ecology by ‘asking’ the animal to reveal its perspective of the environment. Using spatial and temporal foraging decisions—as behavioral indicators—enables us to guide our understanding for across-taxa species coexistence.  相似文献   

8.
9.
For habitat specialists, fragmentation has major consequences as it means less suitable habitat for the species to live in. In a fragmented landscape, we would expect larger, but spatially more clustered, foraging ranges. We studied the impact of landscape fragmentation on the foraging range and habitat exploitation of a specialised forest bat by radiotracking 16 female lesser horseshoe bats Rhinolophus hipposideros in a landscape with connected woodland structures and in a highly fragmented landscape in Carinthia, Austria.Contrary to our expectations, spatial foraging behaviour was not influenced by fragmentation. No differences in the behaviour of the bats between the sites were evident for the foraging ranges (minimum convex polygon, MCP), the core foraging areas (50% kernel), nor the mean or the maximum distances from the roost. However, in the highly fragmented landscape, the foraging activity of individuals was spatially more clustered and the overall MCP of all bats of a colony was greater compared to the less fragmented landscape.Woodland was the most important foraging habitat for the lesser horseshoe bats at both study sites. Habitat selection at the individual MCPs was evident only at the site with low fragmentation. However, in the core foraging areas, woodland was significantly selected over all other habitat types at both study sites.We conclude that (1) conservation measures for colonies of lesser horseshoe bats should be undertaken within 2.5 km of the nursery roost, (2) woodland is the key foraging habitat particularly in the vicinity of the roost, and (3) any loss of woodland near the colonial roosts are likely to negatively influence the colony, since these bats do not seem to be able to adapt their spatial foraging behaviour in a degraded landscape. The inflexible spatial behaviour of this specialised bat highlights the need to compensate for any habitat loss within the foraging range of a bat colony.  相似文献   

10.
In response to global declines in bee populations, several studies have focused on floral resource provisioning schemes to support bee communities and maintain their pollination services. Optimizing host-plant selection for supplemental floral provisioning requires an understanding of bee foraging behavior and preferences for host-plant species. However, fully characterizing these preferences is challenging due to multiple factors influencing foraging, including the large degree of spatiotemporal variability in floral resources. To understand bee pollen foraging patterns, we developed a highly controlled mechanistic framework to measure pollen foraging preferences of the bumble bee Bombus impatiens to nine plant species native to Pennsylvania. We recorded continuous observations of foraging behavior of the experimental bee community and individual bees, while simultaneously standardizing for the number of foragers in the environment and differences in floral display of each plant species, while controlling for flowering phenology such that bees only foraged when all plant species’ flowers were open. Our results demonstrate that B. impatiens exhibit predictable daily patterns in their pollen foraging choices, and their preferences are dominated by the host-plants they visit first. We hypothesize that these patterns at the community and individual levels are driven by the interplay between pollen abundance and quality. We recommend that daily cycles of host-plant visitation be considered in future studies to ensure precise and accurate interpretations of host-plant preference. Such precision is critical for comprehensive analyses of the proximate and ultimate mechanisms driving bee foraging behavior and the selection of host-plant species to use in habitat restoration protocols.  相似文献   

11.
Characterizing insect pollen carriage between closely related plant species is especially challenging where source species possess morphologically identical pollen and share many pollinators in common. Here, we use an SNP-based assay using the plant DNA barcoding locus matK to characterize pollen carriage between cultivated Brassica napus and wild Brassica rapa in three sites across southern England. The assay differentiated B. napus and B. rapa pollen carried by honey bees (Apis melifera), bumblebees (Bombus spp.), mining bees (Andrena spp.) and hoverflies (Syrphidae) captured on B. napus plants 1–2 m from wild B. rapa, and on B. rapa plants at various distances from the crop . Apis individuals foraging on B. rapa and carrying B. napus pollen were rarely found beyond 10 m from the crop. However, Bombus and Andrena individuals captured on B. rapa occasionally carried crop pollen up to 300 m from the source field. Hoverflies carried less pollen overall but featured high proportions of B. napus pollen even at the most distant capture points. We predict that different pollinator species will evoke markedly different patterns of interspecific hybrid formation. We conclude that more exhaustive surveys of this kind will help parameterize future mechanistic models to predict the distribution of hybrids between Genetically Modified B. napus and B. rapa on a landscape scale.  相似文献   

12.
Pollinators and the pollination services they provide are critical for seed set and self‐sustainability of most flowering plants. Despite this, pollinators are rarely assessed in restored plant communities, where their services are largely assumed to re‐establish. Bird–pollinator richness, foraging, and interaction behavior were compared between natural and restored Banksia woodland sites in Western Australia to assess their re‐establishment in restored sites. These parameters were measured for natural communities of varying size and degree of fragmentation, and restored plant communities of high and low complexity for three years, in the summer and winter flowering of Banksia attenuata and B. menziesii, respectively. Bird visitor communities varied in composition, richness, foraging movement distances, and aggression among sites. Bird richness and abundance were lowest in fragmented remnants. Differences in the composition were associated with the size and degree of fragmentation in natural sites, but this did not differ between seasons. Restored sites and their adjacent natural sites had similar species composition, suggesting proximity supports pollinator re‐establishment. Pollinator foraging movements were influenced by the territorial behavior of different species. Using a network analysis approach, we found foraging behavior varied, with more frequent aggressive chases observed in restored sites, resulting in more movements out of the survey areas, than observed in natural sites. Aggressors were larger‐bodied Western Wattlebirds (Anthochaera chrysoptera) and New Holland Honeyeaters (Phylidonyris novaehollandiae) that dominated nectar resources, particularly in winter. Restored sites had re‐established pollination services, albeit with clear differences, as the degree of variability in the composition and behavior of bird pollinators for Banksias in the natural sites created a broad completion target against which restored sites were assessed. The abundance, diversity, and behavior of pollinator services to remnant and restored Banksia woodland sites were impacted by the size and degree of fragmentation, which in turn influenced bird–pollinator composition, and were further influenced by seasonal changes between summer and winter. Consideration of the spatial and temporal landscape context of restored sites, along with plant community diversity, is needed to ensure the maintenance of the effective movement of pollinators between natural remnant woodlands and restored sites.  相似文献   

13.
《Animal behaviour》1987,35(3):794-806
Over the course of one winter, the food supply of birds living in a deciduous woodland in southern England was supplemented and unsupplemented during alternating periods. In the presence of substantial predation pressure from hawks, the sociality of blue tits, Parus caeruleus, and great tits, P. major, showed significant partial correlations with several weather and temporal factors when the woodland was unsupplemented. Such correlations between social behaviour and abiotic factors diminished significantly when the birds had access to extra food. Blue tits and great tits without access to supplemental food flocked significantly more often with other species while foraging than when they were food-supplemented. Long-tailed tits, Aegithalos caudatus, ignored the artificial food and foraged in mixed-species flocks to the same extent in both unsupplemented and food-supplemented periods. Results disprove the hypothesis that mixed-species foraging groups are caused by increased predation protection alone, and they support the hypotheses that mixed-species foraging groups are caused by increased foraging efficiency alone or by a combination of increased foraging efficiency and increased protection from predators.  相似文献   

14.
《Journal of Asia》2023,26(2):102047
Oilseed rape is the third-largest source of vegetable oil and the second-largest source of protein meal in the world. Pollinators are vital in the production of oilseed rape. However, pollination efficiency could be influenced by the morphology and foraging behaviors of pollinators. To evaluate the effect of pollinator size and foraging behavior on pollination efficiency, the intertegular distances (ITDs) of five bumble bees (Bombus pyrosoma, B. lantschouensis, B. melanurus, B. sichelii and B. sibiricus) and two honey bees (Apis mellifera and A. cerana) were evaluated. Their foraging activities and single visit depositions (SVDs) on oilseed rape were observed and counted. The ITDs of bumble bees were significantly larger than honey bees (P < 0.05). The single-visit duration of A. mellifera (2.43 ± 0.06 s) was significantly longer than other bees (P < 0.05). The interval time of the A. cerana was longer than other bees (P < 0.05). Larger bees tended to deposit more pollen on stigmas at each visit than smaller bees. The interspecific ITD of bees had a positive effect on SVD (P < 0.001). There was no correlation between ITD and SVD among individuals of the same species. In conclusion, the size of bees had a positive impact on pollination efficiency. Bees with a greater ITD deposited substantially more pollen and had a significantly shorter interval between flowers. Understanding the foraging behavior and pollination efficiency of these bee species and developing habitats to support them should enable growers to achieve resilient production.  相似文献   

15.
The genus Phaius is distributed mainly in pantropical areas, and most species reported are autogamous. In contrast, Phaius delavayi, an alpine plant endemic to temperate zones of China, is strictly pollinator dependent. Only female workers and males of the bumblebee species B. hypnorum and B. lepidus are effective pollinators. The pollinaria are deposited on top of the head or the prothorax of the pollinators. The different depositions of pollinaria are regarded as an adaptation of the chamber dimensions of the flower to the size of the pollinator. The natural fruit set reported here (24.6–37.1%) suggests that pollination is successful in the deceptive P. delavayi. The yellow perianth and sweet floral scent of P. delavayi are important cues in attracting pollinators, while flowering time and mass population are associated with the process of “learning and avoidance” of the rewardless flowers. This orchid, therefore, employs a deceptive pollination strategy with diverse pollinators and pollinaria depositions rather than autogamy as do its congeners.  相似文献   

16.
The effects of floral species composition on offspring performance of solitary bees are rarely studied under conditions where foraging behaviour of mothers is allowed to play a role. In a semi-field experiment, we restricted foraging choices of the polylectic mason bee Osmia bicornis L. to flower species belonging to plant families presumably used to different extent: Borago officinalis L. (Boraginaceae), Centaurea cyanus L. (Asteraceae) and Brassica napus L. (Brassicaceae). We quantified the foraging behaviour and brood cell production by mother bees, and compared the quality of offspring in pure and mixed flower species stands. Offspring survival in pure stands was expected to reflect the mothers’ foraging preferences in the mixed stand. Pure stands of B. napus supported highest offspring survival, body mass and fraction of females produced. Offspring survival on C. cyanus and B. officinalis was very low. Larval mortality occurred earlier in brood cells provided with B. officinalis pollen than in brood cells provided with C. cyanus pollen suggesting different effects of pollen quality on early larval and later development. The time spent on different foraging activities correlated with lifetime reproductive output. However, in mixed stands, the proportion of time the bees were foraging on the different flower species did not differ significantly. Foraging behaviour may therefore not generally be a good proxy for the quality of floral resources for offspring production. Our results suggest that resources collected from one plant species may influence the usefulness of resources from another plant species. Bees may therefore overcome potentially deleterious effects of the suboptimal resources by mixing low- and high-quality resources. This may help generalist bees, such as O. bicornis, to cope with an unpredictable environment.  相似文献   

17.
Spatial analysis of remotely-sensed land cover data in conjunction with species distribution atlases can reveal large-scale relationships between animal taxa and their habitats. We investigated the historical distribution patterns of three declining woodland birds, the Marsh Tit (Poecile palustris), Willow Tit (Poecile montana) and Lesser Spotted Woodpecker (Dendrocopos minor), in relation to a parsimonious landscape metric for describing habitat availability in Britain. Bird distributions were derived from two field-based atlas surveys, conducted in 1968–1972 and 1988–1991, and used to classify areas of the landscape for each species as retained, lost or gained between atlas periods, or unoccupied in both. We used remotely-sensed land cover data from 1990 to compare percentage habitat cover between landscape areas classified by bird occupation, and regional summary data from national woodland inventories to investigate changes in habitat cover and bird distributions. Percentage habitat cover was a sufficient landscape metric to explain the distribution pattern of all three bird species; habitat cover was greatest in areas where each species was retained between atlas surveys, significantly less in areas from which species were lost, and least in areas that remained unoccupied. Reductions in Marsh Tit distribution were less in regions that showed greater increases in habitat cover, but there was no such relationship for other species. Results indicated that spatial studies could be used to infer aspects of the spatial ecology of species where field data is lacking: by comparing distribution patterns with the relatively well-studied Marsh Tit, we found support for the assumption that the Lesser Spotted Woodpecker occupies very large territories in Britain, and provided evidence that the spatial habitat requirements of the Marsh Tit could be used as a proxy for the data-poor Willow Tit. The results showed that the habitat cover required to retain each species in the landscape had increased over time, illustrating how spatial studies can be used to identify priorities for further research and suggest conservation measures for declining species, and these are discussed.  相似文献   

18.
Highly variable microsatellites enabled a precise assessment of the number of queen matings in the colonies of five bumble bee species. Fifteen of the sixteen microsatellites initially cloned from B. terrestris had flanking regions similar enough to allow PCR amplification on the other Bombus species analysed. The microsatellites selected for intracolony study (four per species) were characterized by a high heterozygosity (0.58–0.93) and a large number of alleles (3–18) in the local populations from which the colonies originated. A single male appeared to have inseminated the queens in the colonies of four species, B. terrestris, B. lucorum, B. lapidarius and B. pratorum, which belong to three subgenera, whereas two of the three analysed colonies of B. hypnorum were polyandrous (minimum number of two and four patrilines, respectively).  相似文献   

19.
Sensitivity to habitat fragmentation often has been examined in terms of thresholds in landscape composition at which a species is likely to occur. Observed thresholds often have been low or absent, however, leaving much unexplained about habitat selection beyond initial thresholds of occurrence, even for species with strong habitat preferences. We examined responses to varying amounts of tree cover, a widely influential measure of habitat loss, for 40 woodland bird species in a mixed woodland/grassland landscape in eastern North Dakota, USA. We used LOESS smoothing to describe incidence for each species at three scales: within 200, 400, and 1200 m around sample locations. For the 200‐m scale, we also calculated the most‐preferred range of tree cover (within which at least half of observations were predicted to occur) for each species. Only 10 of 40 species had occurrence thresholds greater than about 10% tree cover. After initial occurrence, species showed three general patterns: some increased monotonically with tree cover; some increased up to an asymptote; some peaked at intermediate amounts of tree cover and then declined. These patterns approximate selection for interior woodlands and for edge‐rich environments, but incidence plots provide greater detail in landscape‐scale selection than do those categories. For most species, patterns persisted at larger scales, but for some, larger scales had distinctly different patterns than local scales. Preferred ranges of tree cover varied from <20% tree cover (common grackle, Quiscalus quiscula) to >60% (veery, Catharus fuscescens). We conclude that incidence patterns provide more information on habitat selection than do threshold measures for most species: in particular, they differentiate species preferring concentrated woodlands from those preferring mixed landscapes, and they show contrasting degrees of selectiveness. [Correction added on 16 October 2012, after first online publication: the Abstract section has been reworded].  相似文献   

20.
Incorporating ecological processes and animal behaviour into Species Distribution Models (SDMs) is difficult. In species with a central resting or breeding place, there can be conflict between the environmental requirements of the ‘central place’ and foraging habitat. We apply a multi-scale SDM to examine habitat trade-offs between the central place, roost sites, and foraging habitat in Myotis nattereri. We validate these derived associations using habitat selection from behavioural observations of radio-tracked bats. A Generalised Linear Model (GLM) of roost occurrence using land cover variables with mixed spatial scales indicated roost occurrence was positively associated with woodland on a fine scale and pasture on a broad scale. Habitat selection of radio-tracked bats mirrored the SDM with bats selecting for woodland in the immediate vicinity of individual roosts but avoiding this habitat in foraging areas, whilst pasture was significantly positively selected for in foraging areas. Using habitat selection derived from radio-tracking enables a multi-scale SDM to be interpreted in a behavioural context. We suggest that the multi-scale SDM of M. nattereri describes a trade-off between the central place and foraging habitat. Multi-scale methods provide a greater understanding of the ecological processes which determine where species occur and allow integration of behavioural processes into SDMs. The findings have implications when assessing the resource use of a species at a single point in time. Doing so could lead to misinterpretation of habitat requirements as these can change within a short time period depending on specific behaviour, particularly if detectability changes depending on behaviour.  相似文献   

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