Coexistence and host use by a large community of Pierid butterflies: habitat is the templet

Summary We report studies on the butterfly-hostplant communities in the species-rich area of west central Morocco. Pieridae feeding on Capparales form two distinct ecological guilds: inflorescence feeders and folivores. Several members of each guild may synchronously occur in sympatry. Substantial levels of cannibalism and inter-specific predation occur amongst the inflorescence feeders. No evidence was obtained for segregation of butterfy species on different hosts. Host plants included in the diet of specialists were also used by generalists. Despite substantial differences observed in laboratory trials of larval survivorship on different hostplants, results were congruent for all Pieridae, suggesting that little one-to-one insect-host coevolution has occurred. Host specialization was instead related to the year-to-year stability of host numbers in an area. High levels of pierid infestation occurred on host species with numerically stable populations. Host numerical stability was correlated with habitat type. There is little evidence for segregation of competing inflorescence feeders by hostplant species, but some evidence for segregation by habitat type (particularly by shading levels). We interpret our results as indicating that the hostplant affiliations of Moroccan Capparales-feeding Pieridae are subject to (at best) diffuse coevolutionary effects from hosts and competitors, and are strongly influenced by habitat characteristics.     

Putting competition strategies into ideal free distribution models: habitat selection as a tug of war

When resources are patchily distributed in an environment, behavioral ecologists frequently turn to ideal free distribution (IFD) models to predict the spatial distribution of organisms. In these models, predictions about distributions depend upon two key factors: the quality of habitat patches and the nature of competition between consumers. Surprisingly, however, no IFD models have explored the possibility that consumers modulate their competitive efforts in an evolutionarily stable manner. Instead, previous models assume that resource acquisition ability and competition are fixed within species or within phenotypes. We explored the consequences of adaptive modulation of competitive effort by incorporating tug-of-war theory into payoff equations from the two main classes of IFD models (continuous input (CI) and interference). In the models we develop, individuals can increase their share of the resources available in a patch, but do so at the costs of increased resource expenditures and increased negative interactions with conspecifics. We show how such models can provide new hypotheses to explain what are thought to be deviations from IFDs (e.g., the frequent observation of fewer animals than predicted in "good" patches of habitat). We also detail straightforward predictions made uniquely by the models we develop, and we outline experimental tests that will distinguish among alternatives.     

Gradients of salinity stress, environmental stability and water chemistry as a templet for defining habitat types and physiological strategies in inland salt waters

The search for pattern in the geographic occurrence of salt lake flora and fauna often reveals strong associations of specific taxa with certain types of water chemistry. Solute composition, along with salinity and habitat stability, may provide a templet shaping the distribution of many organisms inhabiting saline lakes. A review of studies demonstrating habitat associations, specific solute tolerance, and ionic and osmotic adaptations provide evidence of fidelity to particular conditions of environmental chemistry across a wide taxonomic spectrum. Under low salinity conditions, some species show osmoregulatory adaptability to varied solute composition but the capacity for such flexibility is reduced with increased salinity and only certain taxa are found in hypersaline waters dominated by a particular solute. Anionic ratios of chloride, bicarbonate–carbonate, and sulfate appear to be especially important determinants of distribution. Specific solute tolerance presents an alternative explanation to disrupted hydrographic connections in describing how biogeographic distributions may be restricted to certain aquatic habitats in arid regions. Physiological adaptations to chemistry, exemplified in the brine fly genus Ephydra, may be an integral part of the evolution, ecology and diversification of saline water organisms.     

Species‐habitat associations change in a subtropical forest of China

Question: Do tree and shrub species in an evergreen broadleaf forest show similar habitat associations across different life stages? Location: A 24‐ha evergreen broadleaf forest plot in a heterogeneous landscape in Gutianshan National Nature Reserve, Zhejiang Province, Eastern China. Methods: Species having positive associations with four habitat types (low valley, low ridge, upper valley, and upper ridge) at three life stages (sapling, juvenile, and mature stages) were compared for 60 tree and shrub species using torus‐translation tests. Results: A total of 117 significant positive associations with the four habitats were observed at the three life stages (43, 41, and 33 at the sapling, juvenile, and mature stages, respectively). For the 52 species significantly associated with habitats, only 16 were associated with the same habitat across all three stages. The majority of associated species at the juvenile stage (34 out of 40) were associated with the same habitat at their sapling stage, whereas half of species at the mature stage had consistent associations with the same habitat at their sapling stage. More species were associated with the upper ridge at the sapling and juvenile stages compared to the mature stage. Conversely, more species were associated with the low valley at the mature stage compared to the sapling and juvenile stages. Conclusions: Our results indicate that species ecological habitat associations can differ between developmental stages beyond 1 cm DBH, as most species habitat preferences were consistent from the sapling stage to the juvenile stage but changed at the mature stage.     

Relationship among settling,demography and habitat selection: an approach and a case study

Summary We explore the demographic consequences of site selection by animals on their abundance among habitats. We found that pre and post settling survivorship are important links between the behavioral decisions where to settle and the distribution of a population among habitats. This was demonstrated for 10 generations of the desert isopod, Hemilepistus reaumuri, in three habitats in the Negev Desert, Israel. The populations exhibit low survivorship before settling (12%) and high survivorship (55%) after settling. According to our model this implies high site selection. Theoretical considerations and the case study led us to suggest the following relationship among settling, demography and habitat selection: 1) Individuals search for suitable settling sites to inhabit and reproduce. 2) Their decision where and when to settle is a cost benefit decision. They weigh the benefit of searching for a high quality site against mortality due to increased searching time. 3) The individual's decision to settle determines the pre and post settling survivorship pattern. 4) Survivorship pattern dictates density pattern in time and space. 5) Density pattern in a given habitat determines its quality for the individual. 6) Settling selection among habitats and the number of safe sites controls the distribution of densities among habitats.     

Environmental drivers inducing habitat expansion and shift of introduced alien trout in the Himalayan ecosystem and management concerns

There is a concern of the spread of introduced trout Salmo trutta and Oncorhynchus mykiss which might have potential effects on native fish species in the Himalaya. We present the first assessment of current habitat expansion of introduced trout induced by environmental drivers and posing threats to the local fish diversity. Maximum Entropy (MaxEnt) model was used and overlaid with presence-only data onto bioclimatic and environmental layers to characterize the conditions most suitable for the habitat expansion of trout. Mean AUC value for S. trutta was 0.919 and 0.881 for O. mykiss respectively showing that the MaxEnt model was highly accurate and statistically significant. The precipitation of driest quarter (Bio_17) alone accounted for 71.4% habitat expansion of S. trutta across rivers’ length and 61.1% in the case of O. mykiss. The Jackknife test of different environmental variable particularly Bio_17 and the coldest quarter (Bio_19) depicted their potential role in habitat expansion. The occurrences of trout in the Himalayan streams predicted trade-offs between few environmental variables and habitat expansion. The findings suggested that habitat expansion of trout was induced by identified environmental drivers impacting the array of biological and ecological integrity in the new geographic spaces concerning trout invasion.     

中国大陆鸟类栖息地选择研究十年

栖息地选择研究一直是鸟类生态学研究的重要内容之一。通过对2001年1月至2010年12月10年期间中国大陆鸟类学家在国内外期刊上发表的鸟类栖息地选择研究的论文进行分析,对我国鸟类栖息地选择研究提出展望。10年间,我国鸟类学家共发表有关鸟类栖息地选择或利用的论文170篇,共涉及到鸟类10目31科73种。在这10年里,中国大陆有关鸟类栖息地选择或利用的文章持续增长。然而,我国鸟类栖息地选择的研究也存在着如下问题:(1)存在栖息地选择和栖息地利用误用的现象,这种现象在10年内并无明显改善;(2)在选择研究方法时,很少考虑个体的可获得性、种群密度及抽样尺度对栖息地选择的影响;(3)大多数的栖息地选择的论文没有对鸟类的栖息地选择行为进行研究,也缺乏对其选择的适合度背景去进行研究。根据这些问题,对我国未来的鸟类栖息地选择研究提出了建议。     

Migratory strategies, fawn recruitment, and winter habitat use by urban and rural mule deer (Odocoileus hemionus)

We examined the migratory strategies of mule deer (Odocoileus hemionus) using adjacent urban and rural winter ranges in northern Utah in relation to deer demography and patterns of habitat use. Urban deer were more likely to be migratory than rural deer, even though migratory animals from the two herds intermixed on a common, high-elevation summer range. Urban deer exhibited lower fawn recruitment than rural deer; but within each herd, demographic characteristics of migratory and nonmigratory animals suggested that game theory explained the ratios of deer adopting each behavior. Estimates of animal numbers and available habitat did not reveal clearly whether deer densities differed on the two winter ranges. However, patterns of habitat use by urban deer were so clustered around areas of concealment vegetation that animals probably experienced higher local densities than rural animals. In addition, the clustered patterns of habitat use by urban deer resulted in incomplete use of available forage. This may have contributed to the relatively poor fawn recruitment by urban deer, a phenomenon that appeared to be perpetuated by their strong fidelity to winter range.     

Feeding strategies of Japanese monkeys against deterioration of habitat quality

Field observations of the feeding behaviour of Japanese monkeys were carried out from autumn to winter on Kinkazan Island which is covered with cool temperate forest. As a result, the following two points became clear: (1) the available food items were fixed for a long time; and (2) the habitat quality deteriorated monotonously because the monkeys themselves or their competitors, such as wild mice, utilized the food resources. Against the decrease in food intake caused by this deterioration of the habitat quality, the monkeys controlled the decrease in food intake by employing the following strategies: (1) they recovered their feeding speed by exploiting new food patches (patch-increase strategy); (2) they extended the time spent on feeding (time-extension strategy); and (3) they changed their food (food-change strategy). The former two strategies operated earlier than the third one.     

Alternate plant life history strategies and coexistence in randomly varying environments

Environmental fluctuations can in theory allow the coexistence ofecologically similar species by time-sharing a niche, as envisioned by Hutchinson. The evolution of this situation is studied in a competition model, using as an example the evolution of seed germination strategies. Coexistence occurs via the evolution of low-risk and high-risk strategies for dealing with the variability by different species. Coexistence is promoted by intermediate levels of variability or disturbance, and by a trade-off between seed yield and seed survivorship. These results may be applicable also to other low vs. high risk life history options in unpredictably varying environments, such as: stress resistance vs. potentially rapid growth, high adult survivorship vs. high reproductive output. The model's predictions differ from those obtained without consideration of life history evolution in response to environmental variability, and are consistent with some recent studies of plant strategies in intermittently stressed communities.I thank A. Shmida for many discussions on this topic, D. Cohen and I. Noy-Meir for comments after a seminar presentation of this paper, and H. de Kroon, H. During, and E. Van der Maarel for decreasing my ignorance of the empirical literature.Research conducted while the author was recipient of a Sir Charles Clore Postdoctoral Fellowship in the Department of Applied Mathematics, Weizmann Institute of Science, Rehovot, Israel.     

Community stability,complexity and species life history strategies

The essence of the contradiction between traditional ecological complexity-stability hypothesis and recent theoretical results is clarified. The distinction between resilience and resistance is stressed. The possibilities of field verification of May's model are discussed. No satisfactory method for estimation of connectance and mean interaction strength in plant communities has been found. Relation between these parameters and stability in real communities remains an open question. The relation between connectance and stability (resilience) in purely competitive model communities is more complicated than May's rule predicts. The certain value of connectance having been achieved, stability increases with increasing connectance. We assessed the positive relation between species diversity and resistance, and negative relation between species diversity and resilience in plant communities during old-field succession in xeric habitat. But there is no causal relationship between species diversity and both kinds of stability. Resistance and resilience of the plant communities studied were determined primarily by life history strategies of constituent species. The results are interpreted in terms of Grimes' life history strategies and imply the validity of Gleasonian, population-centered explanation of community phenomena.The nomenclature of plants follows F. Ehrendorfer, 1973, Liste der Gefässpflanzen Mitteleuropas, 2. Aufl. G. Fischer, Stuttgart.Acknowledgements. We thank Pavel Kindlmann for helpful discussion. We are also grateful to reviewers for suggesting ways to improve this paper.     

Environmental life cycle assessment of a commercial office building in Thailand

Background, aim, and scope  To minimize the environmental impacts of construction and simultaneously move closer to sustainable development in the society, the life cycle assessment of buildings is essential. This article provides an environmental life cycle assessment (LCA) of a typical commercial office building in Thailand. Almost all commercial office buildings in Thailand follow a similar structural, envelope pattern as well as usage patterns. Likewise, almost every office building in Thailand operates on electricity, which is obtained from the national grid which limits variability. Therefore, the results of the single case study building are representative of commercial office buildings in Thailand. Target audiences are architects, building construction managers and environmental policy makers who are interested in the environmental impact of buildings. Materials and methods  In this work, a combination of input–output and process analysis was used in assessing the potential environmental impact associated with the system under study according to the ISO14040 methodology. The study covered the whole life cycle including material production, construction, occupation, maintenance, demolition, and disposal. The inventory data was simulated in an LCA model and the environmental impacts for each stage computed. Three environmental impact categories considered relevant to the Thailand context were evaluated, namely, global warming potential, acidification potential, and photo-oxidant formation potential. A 50-year service time was assumed for the building. Results  The results obtained showed that steel and concrete are the most significant materials both in terms of quantities used, and also for their associated environmental impacts at the manufacturing stage. They accounted for 24% and 47% of the global warming potential, respectively. In addition, of the total photo-oxidant formation potential, they accounted for approximately 41% and 30%; and, of the total acidification potential, 37% and 42%, respectively. Analysis also revealed that the life cycle environmental impacts of commercial buildings are dominated by the operation stage, which accounted for approximately 52% of the total global warming potential, about 66% of the total acidification potential, and about 71% of the total photo-oxidant formation potential, respectively. The results indicate that the principal contributor to the impact categories during the operation phase were emissions related to fossil fuel combustion, particularly for electricity production. Discussion  The life cycle environmental impacts of commercial buildings are dominated by the operation stage, especially electricity consumption. Significant reductions in the environmental impacts of buildings at this stage can be achieved through reducing their operating energy. The results obtained show that increasing the indoor set-point temperature of the building by 2°C, as well as the practice of load shedding, reduces the environmental burdens of buildings at the operation stage. On a national scale, the implementation of these simple no-cost energy conservation measures have the potential to achieve estimated reductions of 10.2% global warming potential, 5.3% acidification potential, and 0.21% photo-oxidant formation potential per year, respectively, in emissions from the power generation sector. Overall, the measures could reduce approximately 4% per year from the projected global warming potential of 211.51 Tg for the economy of Thailand. Conclusions  Operation phase has the highest energy and environmental impacts, followed by the manufacturing phase. At the operation phase, significant reductions in the energy consumption and environmental impacts can be achieved through the implementation of simple no-cost energy conservation as well as energy efficiency strategies. No-cost energy conservation policies, which minimize energy consumption in commercial buildings, should be encouraged in combination with already existing energy efficiency measures of the government. Recommendations and perspectives  In the long run, the environmental impacts of buildings will need to be addressed. Incorporation of environmental life cycle assessment into the current building code is proposed. It is difficult to conduct a full and rigorous life cycle assessment of an office building. A building consists of many materials and components. This study made an effort to access reliable data on all the life cycle stages considered. Nevertheless, there were a number of assumptions made in the study due to the unavailability of adequate data. In order for life cycle modeling to fulfill its potential, there is a need for detailed data on specific building systems and components in Thailand. This will enable designers to construct and customize LCAs during the design phase to enable the evaluation of performance and material tradeoffs across life cycles without the excessive burden of compiling an inventory. Further studies with more detailed, reliable, and Thailand-specific inventories for building materials are recommended.     

冬季清凉峰山区小麂和野猪的生境选择及差异

从2005 年11 月5 日至2006 年1 月21 日,为了评估小麂和野猪的生境选择及其差异,我们在浙江清凉峰国家级自然保护区核心区共设置了248 个样方群。研究发现,两者都选择平缓坡的灌丛植被、草本密度小、离住宅较近和离隐蔽物距离适中的生境,表现了它们的生境选择有一定的重叠性。但是它们也表现出生境选择的一些差异,小麂选择乔木密度适中、灌丛密度大和郁闭度适中的生境,而野猪选择乔木密度小的生境,随机地使用各类灌丛密度和郁闭度的生境。小麂还选择北坡、离水源距离较远的生境,野猪只是随机地使用不同的坡向和离水源距离的生境。分析两者共存的机制,我们发现小麂采取隐藏策略而野猪采取逃跑策略来避敌和利用资源,即它们之间存在与反捕食策略相关的生境选择差异。
     

Testing Cort-Fitness and Cort-Adaptation hypotheses in a habitat suitability gradient for roe deer

According to the Cort-Fitness Hypothesis, higher stress levels (glucocorticoids) in vertebrates are correlated to lower fitness. However, recent studies have failed to validate this hypothesis. A proposed wider framework suggests that reproduction can be perceived as an overload adds up to other environmental challenges that individuals must adjust to. In this case, elevated glucocorticoids could help individuals to allocate resources to reproduction without comprising other functions, leading to the expectation of a positive cort-fitness relationship. This has been proposed as the Cort-Adaptation Hypothesis. Stress levels result from a complex interaction between the environment and the neuroendocrine system of animals. Accounting for physiological functions involved in how animals cope with their environment would help to clarify the relationship between glucocorticoids and animal performance. We used roe deer (Capreolus capreolus) inhabiting diverse habitats in the Iberian Peninsula to: i) test the Cort-Fitness and Cort-Adaptation hypotheses by indexing fitness using a comprehensive physiological approach which takes into account fundamental physiological functions and their trade-offs; and ii) evaluate the link between primary productivity and individuals' condition in a seasonal environment. We evaluated spatial and temporal variation in stress levels, reproductive hormone levels, nutritional status and immune function from fecal samples collected in 2010. Lower stress levels were related to better condition in non-reproductive seasons but not to higher primary productivity. In contrast, stress levels were always positively related to reproductive condition, which was better in most productive habitats. Summer and winter were the less productive seasons and the more challenging for the species in the habitat gradient studied. In winter, reproductive condition traded off against immune function being biased toward immune function in less productive habitats. In summer reduced primary productivity limited roe deer nutritional and immunological condition but not reproductive condition. Overall our results match both the Cort-Fitness and Cort-Adaptation Hypotheses.     

Processes regulating early post-settlement habitat use in a subtidal assemblage of brachyuran decapods

In highly mobile animals post-settlement dispersion of juveniles can strongly influence the observed patterns of abundance and distribution. To explore the relative importance of factors regulating the use of habitat by crabs we performed a multi-species manipulative experiment in a subtidal environment of the central Chilean coast. First, demographic patterns were established by performing a year-round crab survey in three discrete and well-known subtidal crab habitats: (1) algal turf, (2) cobbles and (3) shell hash. Second, habitat preferences were experimentally evaluated using concrete trays that were filled with different substrate types that simulate natural habitats. Settlement and recruitment rates were estimated from experimental trays that were left in the field and surveyed after 2 weeks (complete experiment was repeated 7 times throughout 1 year). Third, mortality, due to predation, was assessed by covering 50% of the trays with a 4-mm mesh-size screen that excluded large predators (i.e., fishes, shrimps). Fourth, habitat colonization rates were evaluated by quantifying the arrival, into open trays, of large juveniles (secondary dispersal). The most abundant species in this system (Paraxhantus barbiger, Cancer setosus, Taliepus dentatus and Pilumnoides perlatus) displayed clear habitat preferences at the time of settlement, evidenced by differences in density of recruits among habitats. Recruitment regulation by predation seemed to explain the observed patterns in only one case. For most species, however, evidence of ontogenetic change in the use of habitat, through active habitat redistribution by large juveniles, was detected. Thus, secondary dispersal among habitats seems to outweigh the influence of megalopae's habitat selection and post-settlement mortality as responsible for the observed demographic patterns.     

Environmental networks,compensating life histories and habitat selection by white-footed mice

Summary Analysis of 6 years' data on a population of free-living white-footed mice documents both phenotypic and environmental control of litter size. Litter size was positively correlated with maternal body size. Maternal size depended upon both seasonal and annual variation. Paradoxically, the proportion of small versus large litters varied among habitats independently of the effects of body size. The result is an influence of habitat on life history that yields patterns of reproduction and survival opposite to the predictions of demographic theory. The habitat producing the largest litters had a relatively high ratio of adult/juvenile survival. Litter size was small in the habitat where the adult/juvenile survival ratio was smallest. All of these anomalous patterns can be explained through density-dependent habitat selection by female white-footed mice. Life-history studies that ignore habitat and habitat selection may find spurious correlations among traits that result in serious misinterpretations about life history and its evolution.     

Predator identity and consumer behavior: differential effects of fish and crayfish on the habitat use of a freshwater snail

Predators can alter the outcome of ecological interactions among other members of the food web through their effects on prey behavior. While it is well known that animals often alter their behavior with the imposition of predation risk, we know less about how other features of predators may affect prey behavior. For example, relatively few studies have addressed the effects of predator identity on prey behavior, but such knowledge is crucial to understanding food web interactions. This study contrasts the behavioral responses of the freshwater snail Physellagyrina to fish and crayfish predators. Snails were placed in experimental mesocosms containing caged fish and crayfish, so the only communication between experimental snails and their predators was via non-visual cues. The caged fish and crayfish were fed an equal number of snails, thereby simulating equal prey mortality rates. In the presence of fish, the experimental snails moved under cover, which confers safety from fish predators. However, in the presence of crayfish, snails avoided benthic cover and moved to the water surface. Thus, two species of predators, exerting the same level of mortality on prey, induced very different behavioral responses. We predict that these contrasting behavioral responses to predation risk have important consequences for the interactions between snails and their periphyton resources. Received: 1 June 1998 / Accepted: 12 October 1998     

Life history strategies and psychopathology: the faster the life strategies,the more symptoms of psychopathology

There is little extant empirical literature examining the associations between life history strategies and symptoms of psychopathology. The current study (N = 138) investigated the associations between life history strategies, symptoms of psychopathology, aggression, incidence of self-harm behaviour, and attachment (perceived parental support) in sample drawn from the general population and community mental health service providers. The results from the study indicate those with a faster life strategy report greater levels of aggression and symptoms of psychopathology. Further, perceptions of poorer parental support were associated with a faster life history strategy. Implications for life history theory, conceptualising psychopathology, and future research directions are discussed.     

Population growth and habitat distribution in cyclic small rodents: to expand or to change?

Habitat selection determined by intraspecific interactions (social behaviour), being either free or despotic, should result in the largest densities in the most favourable habitat at least in late increase and decline phases of cyclic populations. Habitat distribution determined by interspecific effects such as herbivore-plant or predator-prey interactions may result in higher densities in inferior habitats at late peaks and/or declines due to overgrazing of preferred habitats, or invasion of such habitats by specialist predators. An examination of the distributions of the rodent species Clethrionomys glareolus and Microtus agrestis during a population cycle on forest clearcuts at Grimsö, south-central Sweden, demonstrated clear changes towards less preferred habitats during the decline phase, particularly in M. agrestis. Intraspecific competition could be excluded as a cause since the numbers of both species declined simultaneously. There was no sign of overgrazing, while weasels, Mustela nivalis, invaded the preferred M. agrestis habitat during peak–decline. Predation thus appears more important for the local occurrence at early decline, rather than territoriality or other social behaviour. It is concluded that distributions in various habitats do not always reveal any primary habitat selection but, rather, habitat-dependent survival.     

Spatial and temporal habitat use patterns for salt marsh nekton: implications for ecological functions

We synthesized information on temporal and spatial patterns of salt marsh habitat use by nekton in order to infer the importance of five main types of marsh function: reproduction, foraging, refuge from predation, refuge from stressful environmental conditions and environmental enhancement of physiology. We then extended the concept that intertidal gradients regulate habitat use patterns of nekton to a more universal concept that applies to all salt marsh habitats. We contend that all marsh habitats are linked to each other and to adjacent estuarine habitats along a depth gradient that mediates gradients in abiotic and biotic conditions. Tidal, diel and seasonal shifts in the magnitude and direction of these gradients result in gradients in tidal, diel and seasonal variation in biotic and abiotic conditions within the salt marsh. Collectively these gradients form the `marsh gradient'. We propose that patterns of marsh use and ecological function for nekton result primarily from physiological and behavioral responses to this marsh gradient. A comparison of habitat use patterns in the context of the marsh gradient is an important – and underutilized – method to study marsh function and essential fish habitat. We note that our limited insight into the function of the marsh habitat results from a significant lack of information on the occurrence and causes of tidal, diel and ontogenetic marsh use patterns by nekton; this is particularly relevant with respect to data on the variation in environmental conditions along marsh gradients over tidal, diel and seasonal cycles and on how environmental variation on these scales influences nekton behavior, growth and survival.