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1.
1. This study reports the discovery of sympatric populations of antlions (Neuroptera: Myrmeleontidae) and wormlions (Diptera: Vermileonidae) in a unique system of sandy microhabitats in the lowland rainforest of Borneo. The two species convergently evolved sit‐and‐wait predatory larvae, which construct pitfall traps to hunt insects. Despite similar specialised foraging strategies, the two species coexist in the competitive environment of small, isolated sandy patches in the rainforest, which begs the question: what biological characteristics allow their coexistence? 2. Based on larval morphology alone, it was predicted that antlions would build larger traps, which would allow them to efficiently hunt larger prey. Addressing this hypothesis, this study compared the volumes of traps constructed by the two species under field and laboratory conditions. A laboratory experiment compared their efficiency of capture of three ant species that differed in body size. 3. The results show that antlions constructed larger traps and captured prey more efficiently. The difference between the species could not be explained by trap size alone. The findings demonstrate that the overlap in resource use in these two species was low, and it is suggested that there is a separation in prey utility between them, allowing their coexistence in the space‐limited habitat of the tropical rainforest.  相似文献   

2.
Abstract 1. Pit‐building antlions are small sit‐and‐wait arthropod predators, which dig conical pits in sandy soils. We studied how biotic (conspecific density and feeding regime) and abiotic (sand depth) factors affect pit diameter and depth, while taking into account the larval body mass. 2. Pit diameter increased with larval body mass at a decelerating rate. In addition, larger larvae tended to relocate less frequently than smaller ones. 3. Sand depth positively affected overall pit size, while increasing conspecific density had a weaker but negative effect on pit size. 4. Feeding the antlions resulted in an increase in pit diameter compared with an unfed control group. However, as prey size increased this positive effect diminished. This result suggests that the existence of prey provides information about the quality of the microhabitat, triggering pit extension. However, similarly to the reduction in the foraging effort of saturated predators, antlions provided with large prey invested only little effort in pit enlargement. 5. Antlions were previously shown to be sensitive to prey and conspecific vibrations in the sand. We thus expected the feeding regime of the neighbour to affect antlion behaviour – surrogate of discriminating between local and global shortage of prey. Nevertheless, antlions with fed neighbours (a local prey shortage) did not show different behaviour compared with a control group in which both antlions were unfed (a global prey shortage).  相似文献   

3.
1. Focusing on the current environmental characteristics, the ‘habitat template’ theory proposes that life‐history strategies summarise how evolution has shaped species to cope with the temporal and spatial variability of their present environment. The hierarchical ‘landscape filters’ concept predicts that the distribution of species reflects their specific traits that allow them to pass through multiple habitat filters. Together, these theories showed the importance of identifying the functional relationships of species to selective habitat forces in order to predict the organisation and response of communities to the environment. 2. We test the relationships between life‐history traits of European freshwater fish species’ and their habitat preferences, to detect the strategies adopted by fish to cope with their current habitat. For this purpose, we use published data on species traits and habitat preferences (microhabitat hydraulics, temperature and oxygen level). We use multivariate analyses to classify fish species’ strategies and test the relationships between strategies and habitat preferences. 3. We identified a continuum of life‐history patterns between two extremes, with opportunistic and periodic species. Our study supports the idea that microhabitat hydraulics plays a more important role as a template for these species ecological strategies than temperature and oxygen level. Indeed, riffle habitats may select opportunistic species whereas weak relationships are found between species strategies and both their temperature and oxygen level preferences. In addition, the ratio between mortality and growth rate (dimensionless trait), reflecting a trade‐off between growth and survival, varied among species according to the use of their hydraulic habitat, with species using deep habitats exhibiting the highest values. 4. These general relationships between hydraulics and traits may be of importance in community ecology to develop predictive models to understand how fish communities change with the hydraulic environment.  相似文献   

4.
Behavioral plasticity allows animals to maximize their fitness in a variety of environmental conditions. Trap‐building predators represent case studies in such plasticity as the characteristics of their traps are dependent upon the substrate available. We investigated the effect of sand particle size on pit construction in antlions (Euroleon nostras), sand‐dwelling insect larvae that build pitfall traps to capture prey. The pit construction behavior of the species comprises six stages. When antlions were exposed to different sand particle sizes, their behavior differed in terms of the occurrence and duration of particular stages and in the frequency of jerks produced during sand tossing. Jerk frequency was negatively correlated with sand particle size and also changed during pit construction. Furthermore, at larger particle sizes, individuals occasionally constructed irregular traps with a figure of eight shape, and they crossed the center of the truncated cone during deepening. In the largest substrate, particle size of antlions did not construct pits. Our results demonstrate that variation in traps under differing environmental conditions stems directly from behavioral plasticity in this species.  相似文献   

5.
Summary Although it is well established that coexisting heteromyid rodent species forage in different microhabitats, we do not yet know the basis for divergent microhabitat choice. One possibility is that seed harvest rates differ among microhabitats, and each species forages where it can extract seeds most efficiently. Microhabitats vary in several factors that could affect heteromyid foraging efficiency, including seed density, soil organic content and particle size distribution. We have explored the effect of each of these variables on harvest rates of several species feeding from petri dishes containing known densities of millet seeds embedded in soil of known particle size and density. Results indicate that the number of seeds harvested per second increases uniformly with seed density and soil density and decreases with soil particle size. Body size affects these relationships: larger animals have higher harvest rates for a given set of conditions and experience a greater relative change in harvest rate for a give change in conditions. This implies that heteromyids can be expected to exhibit species-specific microhabitat preferences while foraging in nature.  相似文献   

6.
1. Animal personality is defined as the repeatable between‐individual differences in behaviour over time and contexts. Some personality traits, such as activity or aggression, have received much attention while other behaviours, such as habitat preference or learning, have been neglected. 2. Wormlion larvae are sit‐and‐wait dipteran predators that inhabit shaded microhabitats in the field and also prefer shade in the laboratory. The aim of the present study was to examine wormlion larvae behavioural repeatability in general and specifically in the context of habitat preference. In order to achieve this, three experiments were conducted to determine whether, to what extent and under which conditions wormlion preference for shaded microhabitats is repeatable. 3. Individual tendency to relocate when the environment conditions deteriorate was also assessed, by switching between shaded and illuminated conditions, either with or without pit destruction. 4. Larvae showed a highly repeatable preference for shade. Repeatability was detected in additional behavioural traits: pit construction, pit area and tendency to relocate. 5. This behavioural repeatability was demonstrated under constant microhabitat conditions, with distinct behaviours in each setting. Under constant illumination, wormlions constructed smaller pits, moved over longer distances and were found at the tray edges more frequently than under constant shade conditions, suggesting that illuminated environments are perceived as risky or unsuitable. 6. Switching between the two microhabitat conditions without pit destruction induced fewer relocations than switching with pit destruction, suggesting that wormlions do not tend to abandon their pits, even if their microhabitat conditions deteriorate.  相似文献   

7.
Summary Habitat selection whereby individuals within a population have different microhabitat preferences is possibly important for genetic diversity and stability. It has received a good deal of attention, especially forDrosophila populations. The literature is summarized and an attempt is made to reconcile what appear to be contradictory findings. Some generalizations are drawn: (1) individualDrosophila choose habitats in consistent and characteristic ways; (2) some microhabitat differences are more important to flies than others; (3) genetic factors influence habitat preferences; (4) experiential factors influence habitat preferences; (5) differences in processing ability moderate the influence of experience on habitat choice. It is argued that the traditional analysis of variance models are frequently not very helpful for visualizing the process, and a computational model is suggested instead.  相似文献   

8.
Wildlife management policies are often based on expert perceptions of the ecological importance of certain species and poorly informed perceptions of how public attitudes toward management are formed. Little is known about why preferences vary greatly and how this affects support for management actions. This paper explores preferences for a range of wildlife species among a sample of the rural population adjacent to Serengeti National Park in Tanzania. We also examine the degree of acceptance for alternative management interventions when potentially dangerous animals pose different levels of problems to human beings, and the extent to which these attitudes are related to species preferences. Gender has a significant effect on species preferences. Men like most species better than women. Age has no significant effect, but level of education affects preference level for some species. Species preferences have a positive effect on support for management intervention when dangerous animals cause small or moderate problems to humans, i.e. there is a higher degree of acceptance of problems caused by animals that are well liked. In situations where human life is threatened, species preferences have no effect on preferred management actions. Appreciation of animals is a combination of functional, consumptive and cultural dimensions, and there is no simple link between species preferences and attitudes toward management actions. The local context and concrete experience with wildlife encounters is more important for shaping normative beliefs like attitudes towards management actions than global wildlife attitudes.  相似文献   

9.
1. Starvation tolerance is an important trait for animals, as most will encounter starvation within their lifetime. Sit‐and‐wait predators are better adapted to starvation owing to their naturally low encounter rate with prey. 2. Starvation tolerance was studied under three levels of disturbance of wormlion larvae, a strict sit‐and‐wait predator that constructs pits. 3. Frequently disturbed wormlions constructed pits less often, and larger individuals continued to construct pits more frequently than smaller ones. It was expected that a high disturbance level would lead to a high rate of mass loss, however, surprisingly, the rate of mass loss was not higher for the frequently disturbed group. This suggests that the energetic cost of pit construction and maintenance is not as high as previously suggested for other pit‐building predators. 4. Larger individuals tolerated starvation better, in losing a lower proportion of their initial body mass and having higher chances of survival throughout the experiment. 5. The effect of starvation on the distance to neighbours was also investigated, and starved individuals were expected to maximise this distance in order to avoid interference competition. However, wormlions were usually clumped, and starvation or feeding had no effect on the pits' spatial pattern, suggesting that interference competition plays a minor role in this species. 6. Generally, wormlion larvae demonstrated a high starvation tolerance and low mortality rates even after 9 weeks of starvation.  相似文献   

10.
Contrary to assumptions of habitat selection theory, field studies frequently detect ‘ecological traps’, where animals prefer habitats conferring lower fitness than available alternatives. Evidence for traps includes cases where birds prefer breeding habitats associated with relatively high nest predation rates despite the importance of nest survival to avian fitness. Because birds select breeding habitat at multiple spatial scales, the processes underlying traps for birds are likely scale‐dependent. We studied a potential ecological trap for a population of yellow warblers Dendroica petechia while paying specific attention to spatial scale. We quantified nest microhabitat preference by comparing nest‐ versus random‐site microhabitat structure and related preferred microhabitat features with nest survival. Over a nine‐year study period and three study sites, we found a consistently negative relationship between preferred microhabitat patches and nest survival rates. Data from experimental nests described a similar relationship, corroborating the apparent positive relationship between preferred microhabitat and nest predation. As do other songbirds, yellow warblers select breeding habitat in at least two steps at two spatial scales; (1) they select territories at a coarser spatial scale and (2) nest microhabitats at a finer scale from within individual territories. By comparing nest versus random sites within territories, we showed that maladaptive nest microhabitat preferences arose during within‐territory nest site selection (step 2). Furthermore, nest predation rates varied at a fine enough scale to provide individual yellow warblers with lower‐predation alternatives to preferred microhabitats. Given these results, tradeoffs between nest survival and other fitness components are unlikely since fitness components other than nest survival are probably more relevant to territory‐scale habitat selection. Instead, exchanges of individuals among populations facing different predation regimes, the recent proliferation of the parasitic brown‐headed cowbird Molothrus ater, and/or anthropogenic changes to riparian vegetation structure are more likely explanations.  相似文献   

11.
Understanding the microhabitat preferences of animals can help managers to develop better conservation and recovery strategies but this is challenging. Traditional methods are limited by cost, accuracy and human resources. In this study, we investigated avian microhabitat preferences using microphone arrays that are capable of accurately locating vocalizing birds. Our objective was to identify the microhabitat associations of two common species in steep population decline, the Boreal Chickadee Poecile hudsonicus and the Cape May Warbler Setophaga tigrina. We deployed 68 eight-channel arrays at random locations in Labrador, Canada, during the 2016 avian breeding season. We returned in 2017 to the 18 array locations where the target species had been detected the previous year and characterized the microhabitat at the exact locations where they had been detected. We also characterized the microhabitat at randomly determined control locations. Results show that Boreal Chickadees select trees with greater diameter-at-breast-height that are surrounded by greater stem density. We did not find evidence that Cape May Warblers exhibit microhabitat selection during song production. The study shows that microphone arrays are an effective tool for identifying preferred microhabitat that could be incorporated into future conservation or recovery strategies.  相似文献   

12.
M. Z. Sadique and R. Legood Women’s preferences regarding options for management of atypical, borderline or low‐grade cervical cytological abnormalities: a review of the evidence Objectives: To review the evidence on women’s preferences for and valuation of alternative management pathways following identification of low‐grade cytological abnormalities as part of routine cervical cancer screening. The aim was to identify empirical studies evaluating women’s preferences regarding alternative management pathways and to compare the impact of alternative elicitation methods on results. Methods: A systematic review of the literature was conducted using the online bibliographic information service PubMed database. Empirical studies were identified that elicited general preferences, utilities or valuations based on willingness to pay (WTP) with respect to management of low‐grade cytology results. Data were extracted on the methodology used and the empirical results. Results: Where quality of life data were elicited directly from patients that were undergoing management of low‐grade abnormalities utilizing direct elicitation techniques such as WTP, general preference questionnaires and the Euroqol, the studies tended towards a preference in favour of HPV testing (and colposcopy referral if HPV positive) rather than repeat cytology. In contrast, where studies included the general population and presented hypothetical scenarios of treatment pathways, and explicitly tried to incorporate assessment of process utility, the evidence indicated a slight tendency to favour repeat cytology. Conclusion: Consideration of patient preferences in the management of low‐grade cytology is important for designing screening protocols. The reviewed studies indicate that potentially different conclusions may be drawn depending on the elicitation methodology and selection of participants in the research.  相似文献   

13.
By selecting codistributed, closely related montane sedges from the Rocky Mountains that are similar in virtually all respects but one—their microhabitat affinities—we test predictions about how patterns of genetic variation are expected to differ between Carex nova, an inhabitant of wetlands, and Carex chalciolepis, an inhabitant of drier meadows, slopes, and ridges. Although contemporary populations of the taxa are similarly isolated, the distribution of glacial moraines suggests that their past population connectedness would have differed. Sampling of codistributed population pairs from different mountain ranges combined with the resolution provided by over 24,000 single nucleotide polymorphism loci supports microhabitat‐mediated differences in the sedges’ patterns of genetic variation that are consistent with their predicted differences in the degree of isolation of ancestral source populations. Our results highlight how microhabitat preferences may interact with glaciations to produce fundamental differences in the past distributions of presently codistributed species. We discuss the implications of these findings for generalizing the impacts of climate‐induced distributional shifts for communities, as well as for the prospects of gaining insights about species‐specific deterministic processes, not just deterministic community‐level responses, from comparative phylogeographic study.  相似文献   

14.
微生境选择分化是生境相似的物种间共存的重要原因。社鼠和大林姬鼠为北京东灵山地区常见鼠种,生境需求、活动节律及食物组成等相似,但二者共存的原因尚不清楚。2016—2017年,我们对北京东灵山地区社鼠和大林姬鼠的微生境选择进行了研究。不同季节和生境类型中,社鼠和大林姬鼠微生境选择存在明显分化。灌丛生境中,春季社鼠偏好于乔木密度、草本盖度更高和落叶盖度相对偏低的微生境,而大林姬鼠选择郁闭度、落叶盖度较高而草本盖度较低的微生境;主成分分析表明,地表覆盖物是影响二者微生境选择的主要因素;秋季社鼠喜好乔木种类多、灌木密度和草本盖度更高的微生境,而大林姬鼠选择乔木胸径、灌木距离、落叶盖度和空地比例更高的微生境,食物丰富度是影响社鼠和大林姬鼠微生境选择的主要因素。弃耕地生境中,春季社鼠倾向于灌木密度和草本盖度较高的微生境,而大林姬鼠首选郁闭度、乔木胸径、落叶盖度较大而草本盖度较低的微生境,地表覆盖物是影响二者微生境选择的主要因素;秋季社鼠偏好郁闭度和落叶盖度都相对较低的微生境,大林姬鼠则相反,食物多度是影响二者微生境选择的主要因素。次生林生境中,春季因样本量太少,未作分析;秋季社鼠优先选择灌木密度、灌木基径和草本盖度更高的微生境,大林姬鼠更倾向乔木胸径、落叶盖度较高,而灌木密度、草本盖度较低的微生境,地表覆盖物是影响二者微生境选择的主要因素。结果表明,不同生境和季节,两种鼠的微生境选择具有明显分化,这可能是二者共存的重要原因之一。  相似文献   

15.
In bryophytes, the possibility of intragametophytic selfing creates complex mating patterns that are not possible in seed plants, although relatively little is known about patterns of inbreeding in natural populations. In the peat‐moss genus Sphagnum, taxa are generally bisexual (gametophytes produce both sperm and egg) or unisexual (gametes produced by separate male and female plants). We sampled populations of 14 species, aiming to assess inbreeding variation and inbreeding depression in sporophytes, and to evaluate correlations between sexual expression, mating systems, and microhabitat preferences. We sampled maternal gametophytes and their attached sporophytes at 12–19 microsatellite loci. Bisexual species exhibited higher levels of inbreeding than unisexual species but did generally engage in some outcrossing. Inbreeding depression did not appear to be common in either unisexual or bisexual species. Genetic diversity was higher in populations of unisexual species compared to populations of bisexual species. We found a significant association between species microhabitat preference and population genetic diversity: species preferring hummocks (high above water table) had populations with lower diversity than species inhabiting hollows (at the water table). We also found a significant interaction between sexual condition, microhabitat preference, and inbreeding coefficients, suggesting a vital role for species ecology in determining mating patterns in Sphagnum populations. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 115 , 96–113.  相似文献   

16.
Schistosoma mansoni is an important human parasitic disease which is widespread throughout Africa. As Biomphalaria pfeifferi snails act as intermediate host, knowledge of their population ecology is an essential prerequisite towards understanding disease transmission. We conducted a field study and assessed the density and microhabitat preferences of B.pfeifferi in a natural habitat which was a residual pool of a river. Repeated removal collecting revealed a density of 26.6 [95% confidence interval (CI): 24.9-28.3] snails/m2. B. pfeifferi showed microhabitat preferences for shallow water (depths: 0-4cm). They were found most abundantly close to the shoreline (distances: 0-40cm), and preferred either plant detritus or bedrock as substratum. Lymnaea natalensis, a snail which may act as a host for human Fasciola gigantica, also occurred in this habitat with a density of 34.0 (95% CI: 24.7-43.3) snails/m2, and preferred significantly different microhabitats when compared to B.pfeifferi. Microhabitat selection by these snail species was also investigated in a man-made habitat nearby, which consisted of a flat layer of concrete fixed on the riverbed, covered by algae. Here, B.pfeifferi showed no preference for locations close to the shoreline, probably because the habitat had a uniform depth. We conclude that repeated removal collecting in shallow habitats provides reliable estimates of snail densities and that habitat changes through constructions may create favourable microhabitats and contribute to additional disease transmission.  相似文献   

17.
Because they provide a high density and diversity of vertebrate species, small water pools and shaded environments, zoological gardens offer ideal living conditions for numerous mosquito species. Depending on their host preferences and vector competencies, these species may be able to transmit pathogens between native and non‐adapted exotic blood host species, thereby causing morbidity and mortality among valuable zoo animals. To determine the extent to which native mosquito species feed on captive and wild animals, as well as on humans, in two German zoological gardens, mosquitoes were collected over two seasons by trapping and aspirating. A total of 405 blood‐fed specimens belonging to 16 mosquito taxa were collected. Genetic bloodmeal analysis revealed 56 host species, mainly representing mammals of the zoo animal population, including exotic species previously not known as blood hosts of the mosquito species collected. These results indicate opportunistic feeding patterns with low host‐specificity in the analysed mosquitoes, although these could be grouped, according to their bloodmeals, into ‘amphibian‐’, ‘non‐human mammal‐’ and ‘non‐human mammal and human‐’ feeding species. As the blood‐feeding preferences of vector‐competent mosquito species are major determinants of vector capacity, information on the blood‐feeding behaviour of mosquitoes in zoos is crucial to the success of targeted vector management.  相似文献   

18.
动物的生境选择具有空间尺度依赖性, 在不同空间尺度上影响生境选择的环境因素有所不同。研究不同空间尺度下动物生境选择的关键影响因子及其季节性变化, 对于全面了解物种的生境资源需求和开展生境保护具有重要意义。绿尾虹雉(Lophophorus lhuysii)是中国特有的高山雉类, 国家一级重点保护野生动物, 具有极高的保护价值。然而, 目前尚未对其不同尺度和时期的生境选择进行过探究。本研究于2019年10月至2020年10月, 在四川卧龙国家级自然保护区的羊角湾、魏家沟和文扎都3个区域共布设15条样线、303个样方, 并结合红外相机监测(176个红外相机位点), 对保护区内绿尾虹雉种群的生境利用状况进行了调查, 使用主成分分析和逻辑斯蒂回归模型分别从景观和微生境两个尺度对繁殖期(3‒8月)和非繁殖期(9月至翌年2月)的生境选择模式进行了分析。结果显示, 在景观尺度上, 在繁殖期和非繁殖期都显著偏好海拔较高(3,700‒ 4,300 m)、坡度较小(27°‒33°)、靠近阳坡、草甸和流石滩比例较高而森林和灌丛比例较低的生境。在微生境尺度上, 绿尾虹雉在繁殖期显著偏好岩石盖度较高的生境; 而非繁殖期则显著偏好草本盖度较高、灌木盖度和落叶盖度较低的生境。研究表明, 绿尾虹雉在景观和微生境尺度上均对生境有明显的选择性, 并且其微生境选择还存在季节性变化, 反映了该物种在生活史不同阶段具有不同的资源需求。本研究丰富了绿尾虹雉的基础生态学信息, 为卧龙及其他自然保护区绿尾虹雉的生境管理和种群保护工作提供了参考。  相似文献   

19.
Testate amoebae (Protozoa: Rhizopoda) are common inhabitants of peatlands. Strong relationships between community composition and substrate moisture in Sphagnum‐dominated peatlands have made them particularly useful as hydrological proxies in environmental and palaeoenvironmental research. However, stability of these relationships in geographical space is important for widespread applicability. In this study, we compared testate amoeba communities inhabiting Sphagnum‐dominated peatlands of the Great Lakes and Rocky Mountain regions of North America. Our primary objectives were to describe patterns of community composition in the two regions, develop hypotheses to explain differences, and determine if taxa occupy similar ecological niches with respect to substrate moisture in both places. Our results indicated that testate amoeba communities are relatively different in the two regions, and these differences are probably caused by differences in climate and peatland trophic status, although other factors may also play a role. However, many taxa do occur in both regions and these taxa had comparable moisture preferences in each region, suggesting that the ecological niches of taxa with respect to substrate moisture are similar even within communities of relatively different composition.  相似文献   

20.
Different environments are expected to exert differential selective pressures, often generating distinct sets of traits in organisms inhabiting different geographic regions. Starvation endurance is an important trait for organisms in harsh (i.e., extreme climate and/or biotically poor) and unpredictable environments. This is especially true for sit-and-wait predators, such as antlions, which experience stronger fluctuations in prey arrivals than do actively searching predators. We conducted an experimental comparison of starvation endurance in pit-building antlions, originating from semi-arid and hyper-arid environments. We hypothesized that individuals from the climatically harsher and biotically poor environment (i.e., hyper-arid) should be better adapted to endure long starvation periods. Additionally, we posited that faster-growing individuals are expected to be more sensitive to starvation because of their need to sustain higher metabolic rates. We found that antlions originating from the semi-arid region maintained higher activity levels, which led to slightly higher mass loss rates during starvation, but enabled faster recovery when food supply was renewed. Conversely, antlions originating from the hyper-arid region had lower activity levels, consistent with their lower rate of mass loss during starvation, but this came at the expense of decreased response to prey and lower growth rate when food became available again. Each strategy holds its advantages for coping with long starvation periods, and we cannot say decisively which strategy is better. Results from both regions were consistent with the predictions of the growth compensation phenomenon: antlions that were fed less frequently pre-starvation grew at faster rates when food supply was renewed. Our study demonstrates that individuals originating from different environments adopt different strategies in order to endure starvation, exemplifying antlions’ ability to compensate for mass lost during starvation.  相似文献   

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