共查询到20条相似文献，搜索用时 218 毫秒
1.
2.
3.
- 1 Dogs Canis familiaris are the world's most common carnivore and are known to interact with wildlife as predators, prey, competitors, and disease reservoirs or vectors.
- 2 Despite these varied roles in the community, the interaction of dogs with sympatric wild carnivore species is poorly understood. We review how dogs have been classified in the literature, and illustrate how the location and ranging behaviour of dogs are important factors in predicting their interactions with wild prey and carnivores.
- 3 We detail evidence of dogs as intraguild competitors with sympatric carnivores in the context of exploitative, interference and apparent competition.
- 4 Dogs can have localized impacts on prey populations, but in general they are not exploitative competitors with carnivores. Rather, most dog populations are highly dependent on human‐derived food and gain a relatively small proportion of their diet from wild prey. However, because of human‐derived food subsidies, dogs can occur at high population densities and thus could potentially outcompete native carnivores, especially when prey is limited.
- 5 Dogs can be effective interference competitors, especially with medium‐sized and small carnivores. Dogs may fill the role of an interactive medium‐sized canid within the carnivore community, especially in areas where the native large carnivore community is depauperate.
- 6 Dogs can also be reservoirs of pathogens, because most populations around the world are free‐ranging and unvaccinated. Diseases such as rabies and canine distemper have resulted in severe population declines in several endangered carnivores coexisting with high‐density dog populations. Dogs can therefore be viewed as pathogen‐mediated apparent competitors, capable of facilitating large‐scale population declines in carnivores.
- 7 Based on this information, we propose conceptual models that use dog population size and ranging patterns to predict the potential for dogs to be intraguild competitors. We discuss how interactions between dogs and carnivores might influence native carnivore communities.
4.
5.
6.
7.
8.
9.
- 1 Environmental heterogeneity is important in determining the distribution and abundance of organisms at various spatial scales. The ability to understand and predict distribution patterns is important for solving many management problems in conservation biology and wildlife epidemiology.
- 2 The badger Meles meles is a highly adaptable, medium‐sized carnivore, distributed throughout temperate Eurasia, which shows a wide diversity of social and spatial organization. Within Britain, badgers are not only legally protected, but they also serve as a wildlife host for bovine tuberculosis Mycobacterium bovis. An evaluation of the role of badgers in the dynamics of this infection depends on understanding the responses of badgers to the environment at different spatial scales.
- 3 The use of digital data to provide information on habitats for distribution models is becoming common. Digital data are increasingly accessible and are generally cheaper than field surveys. There has been little research, however, to compare the accuracy of models based on field‐derived and remotely derived data.
- 4 In this paper, we make quantified comparisons between large‐scale presence/absence models for badgers in Britain, based on field‐surveyed habitat data and remotely derived digital data, comprising elevation, geology and soil.
- 5 We developed four models: 1980s badger survey data using field‐based and digital data, and 1990s badger survey data using field‐based and digital data. We divided each of the four datasets into two subsets and used one subset for training (developing) the model and the other for testing it.
- 6 All four training models had classification accuracies in excess of 69%. The models generated from digital data were slightly more accurate than those generated from field‐derived habitat data.
- 7 The high classificatory ability of the digital‐based models suggests that the use of digital data may overcome many of the problems associated with field data in wildlife‐habitat modelling, such as cost and restricted geographical coverage, without any significant impact on model performance for some species. The more widespread use of digital data in wildlife‐habitat models should enhance their accuracy, repeatability and applicability and make them better‐suited as tools to aid policy‐ and decision‐making processes.
10.
11.
12.
13.
Spatial patterns in brown bear Ursus arctos diet: the role of geographical and environmental factors
- 1 We reviewed worldwide spatial patterns in the food habits of the brown bear Ursus arctos in relation to geographical (latitude, longitude, altitude) and environmental (temperature, snow cover depth and duration, precipitation, primary productivity) variables.
- 2 We collected data from 28 studies on brown bear diet based on faecal analysis, covering the entire geographical range of this widely distributed large carnivore. We analysed separately four data sets based on different methods of diet assessment.
- 3 Temperature and snow conditions were the most important factors determining the composition of brown bear diet. Populations in locations with deeper snow cover, lower temperatures and lower productivity consumed significantly more vertebrates, fewer invertebrates and less mast. Trophic diversity was positively correlated with temperature, precipitation and productivity but negatively correlated with the duration of snow cover and snow depth. Brown bear populations from temperate forest biomes had the most diverse diet. In general, environmental factors were more explicative of diet than geographical variables.
- 4 Dietary spatial patterns were best revealed by the relative biomass and energy content methods of diet analysis, whereas the frequency of occurrence and relative biomass methods were most appropriate for investigating variation in trophic diversity.
- 5 Spatial variation in brown bear diet is the result of environmental conditions, especially climatic factors, which affect the nutritional and energetic requirements of brown bears as well as the local availability of food. The trade‐off between food availability on the one hand, and nutritional and energetic requirements on the other hand, determines brown bear foraging decisions. In hibernating species such as the brown bear, winter severity seems to play a role in determining foraging strategies. Large‐scale reviews of food habits should be based on several measures of diet composition, with special attention to those methods reflecting the energetic value of food.
14.
- 1 Evidence from the literature, interviews, market surveys, general rapid field surveys and camera trapping was reviewed to infer the regional status of 33 recorded carnivores in South China (Guangxi, Guangdong, Hainan, Hong Kong and Macau).
- 2 The carnivore fauna in South China is among the most depleted for any continental area in the world.
- 3 The tiger Panthera tigris, leopard Panthera pardus, grey wolf Canis lupus and binturong Arctictis binturong are probably extirpated.
- 4 The dhole Cuon alpinus, Asiatic golden cat Catopuma temmincki and clouded leopard Neofelis nebulosa are at great risk of regional extirpation, as are the more ecologically adaptable red fox Vulpes vulpes, raccoon dog Nyctereutes procyonoides, Asian badger Meles leucurus, Eurasian otter Lutra lutra, Oriental small‐clawed otter Aonyx cinereus and large Indian civet Viverra zibetha.
- 5 Though more widely reported, the Asiatic black bear Ursus thibetanus, yellow‐throated marten Martes flavigula, hog badger Arctonyx collaris and Siberian weasel Mustela sibirica are at regional risk.
- 6 The status of the Burmese ferret‐badger Melogale personata, stripe‐backed weasel Mustela strigidorsa, smooth‐coated otter Lutrogale perspicillata, large‐spotted civet Viverra megaspila and Owston's palm civet Chrotogale owstoni is uncertain due to inadequate information.
- 7 Five carnivore species – the Chinese ferret‐badger Melogale moschata, masked palm civet Paguma larvata, yellow‐bellied weasel Mustela kathiah, small Indian civet Viverricula indica and leopard cat Prionailurus bengalensis– are relatively secure (though not common) in the region, along with the Asian palm civet Paradoxurus hermaphroditus and the Javan mongoose Herpestes javanicus in some areas, while the spotted linsang Prionodon pardicolor and crab‐eating mongoose Herpestes urva may have been under‐reported.
- 8 The main threats have been habitat destruction and unsustainable exploitation. Only in Hong Kong, where enforcement of protection legislation has been stronger, are the surviving carnivore species easily encountered.
- 9 Improved enforcement and monitoring are essential to retaining the remainder of South China's carnivores. Support could be boosted by conservation education and better research.
15.
G. Nieto Feliner M. Rosato G. Alegre P. San Segundo J. A. Rossell T. Garnatje S. Garcia 《Plant biology (Stuttgart, Germany)》2019,21(6):1072-1082
- Introgression is a poorly understood evolutionary outcome of hybridisation because it may remain largely undetected whenever it involves the transfer of small parts of the genome from one species to another. Aiming to understand the early stages of this process, a putative case from the southernmost border of the Armeria pungens range from its congener A. macrophylla is revisited following the discovery of a subpopulation that does not show phenotypic signs of introgression and resembles typical A. pungens.
- We analysed morphometrics, nuclear ribosomal DNA ITS and plastid DNA (trnL‐trnF) sequences, genome size, 45S and 5S rDNA loci‐FISH data and nrDNA IGS sequences.
- Within the study site, most individuals match morphologies of either of the two hybridising species, particularly the new subpopulation, with intermediate phenotypes being scarce. This pattern does not fully fit molecular evidence revealing two ITS ribotypes co‐occurring intragenomically in most plants from the study site and one single plastid haplotype. Genome size and structural features of the IGS sequences both indicate that A. pungens from the study site is genetically more similar to its sympatric congener than to the remainder of its conspecifics.
- Introgression of A. macrophylla into A. pungens and plastid capture explain all the evidence analysed. However, important features to understand the origin and fate of the introgressed population, such as the degree and direction of introgression, which are important for understanding early stages of hybridisation in plants with low reproductive barriers, should be addressed with new data.
16.
17.
18.
- 1 The endemic maned sloth Bradypus torquatus is globally threatened due to deforestation, habitat fragmentation and isolation of populations. Despite increased interest in the species in recent years, information on its geographic distribution is limited and is derived mainly from a few museum species and from a survey based mostly on interviews carried out more than 20 years ago. Information on its habitat and altitudinal preferences is lacking. We therefore compile, update and review all occurrence records of this species using geographical information system (GIS) tools and produce a distribution map for the species.
- 2 Our compilation totalled 188 occurrence records, of which 130 (69%) were considered confirmed (museum specimens or individuals captured or seen in the field), most of which (62%) were restricted to the states of Bahia and central‐south Espírito Santo (29%). The species occurs predominantly in ombrophilous forest (80%), from sea level to 1290m, but mainly (79%) below 200m altitude.
- 3 We used GIS techniques and the alpha shape algorithm to calculate the extent of occurrence of the species and compared the resulting map with distribution maps available in the literature. We found a great deal of variation in distribution area shape and an almost two‐fold variation in distribution area size among sources.
- 4 We confirmed the existence of a main distribution gap between southern Bahia and northern Espírito Santo and discovered a second smaller gap between southern Espírito Santo and northern Rio de Janeiro.
- 5 We also confirmed that B. torquatus is sympatric with the common three‐toed sloth Bradypus variegatus in a large part of the Atlantic forest and that the two species are syntopic in at least 11 locations.
19.
20.
Luke C. Evans Richard M. Sibly Pernille Thorbek Ian Sims Tom H. Oliver Richard J. Walters 《Ecology and evolution》2020,10(7):3200-3208
- Dispersal ability is key to species persistence in times of environmental change. Assessing a species' vulnerability and response to anthropogenic changes is often performed using one of two methods: correlative approaches that infer dispersal potential based on traits, such as wingspan or an index of mobility derived from expert opinion, or a mechanistic modeling approach that extrapolates displacement rates from empirical data on short‐term movements.
- Here, we compare and evaluate the success of the correlative and mechanistic approaches using a mechanistic random‐walk model of butterfly movement that incorporates relationships between wingspan and sex‐specific movement behaviors.
- The model was parameterized with new data collected on four species of butterfly in the south of England, and we observe how wingspan relates to flight speeds, turning angles, flight durations, and displacement rates.
- We show that flight speeds and turning angles correlate with wingspan but that to achieve good prediction of displacement even over 10 min the model must also include details of sex‐ and species‐specific movement behaviors.
- We discuss what factors are likely to differentially motivate the sexes and how these could be included in mechanistic models of dispersal to improve their use in ecological forecasting.