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771.
Katie E. Slocombe Tanja Kaller Laurel Turman Simon W. Townsend Sarah Papworth Paul Squibbs Klaus Zuberbühler 《Behavioral ecology and sociobiology》2010,64(12):1959-1966
Chimpanzees produce acoustically distinct calls when encountering food. Previous research on a number of species has indicated
that food-associated calls are relatively widespread in animal communication, and the production of these calls can be influenced
by both ecological and social factors. Here, we investigate the factors influencing the production of food-associated calls
in wild chimpanzees and examine whether male chimpanzees produce food-associated calls selectively in the presence of important
social partners. Male chimpanzees form stable long-term social relationships with each other, and these social bonds are vital
in enabling a range of cooperative activities, such as group hunting and territory defence. Our data show that males were
significantly more likely to produce food-associated calls if an important social partner was nearby, regardless of the size
of the audience or the presence of oestrus females. Call production was also mediated by the size of the food patch and by
whether or not the food could be monopolised. The presence of important social partners explained most of the variation in
male calling behaviour, indicating that food-associated calls are socially directed and serve a bonding function. 相似文献
772.
Miriam Fluckiger George D. Jackson Peter Nichols Patti Virtue Adam Daw Simon Wotherspoon 《Marine Biology》2008,154(2):363-372
Fatty acid analysis is an alternative dietary investigation tool that complements the more traditional techniques of stomach
content and faecal analysis that are often subject to a wide range of biases. In applying fatty acid analysis to ecosystem
studies, it is important to have an understanding of the effect diet has on the fatty acid profile of the predator. A feeding
experiment, using crustacean and fish as prey for the European cuttlefish Sepia officinalis, was conducted to evaluate the effect of prey fatty acids on the fatty acid profile of this marine predator. Cuttlefish were
fed on a fish diet for the first 29 days, and then changed to a crustacean diet for a further 28 days. Another group of cuttlefish
was fed on a crustacean diet for the first 29 days, and then changed to a fish diet for a further 28 days. An analysis of
the cuttlefish digestive gland showed that the fatty acid profile reflected that of the prey, with cuttlefish on a crustacean
diet being clearly distinguishable from the cuttlefish on a fish diet. Cuttlefish fed on a fish diet for 29 days prior to
the switch in diet were comparatively higher in 16:0, AA, 20:1ω9, DPA6, DHA, 22:4ω6 and DPA3 than those fed on crustaceans.
Cuttlefish fed on a crustacean diet for 29 days prior to the switch in diet were comparatively higher in 17:1ω8, 18:1ω9, 18:2ω6,
18:1ω7, EPA and 20:2ω6 than those fed on fish. Following a change in diet, the fatty acid profile of the cuttlefish digestive
gland reflected that of the new diet within 14 days. The results confirm that the fatty acid profile of the cuttlefish digestive
gland clearly reflects the profile of its recent diet. It also shows that the digestive gland may not be an organ that accumulates
dietary lipids for long-term storage, but rather is an organ where lipids are rapidly being turned over and potentially excreted. 相似文献
773.
Macel M Lawson CS Mortimer SR Smilauerova M Bischoff A Crémieux L Dolezal J Edwards AR Lanta V Bezemer TM Van der Putten WH Igual JM Rodriguez-Barrueco C Müller-Schärer H Steinger T 《Ecology》2007,88(2):424-433
Evolutionary theory suggests that divergent natural selection in heterogeneous environments can result in locally adapted plant genotypes. To understand local adaptation it is important to study the ecological factors responsible for divergent selection. At a continental scale, variation in climate can be important while at a local scale soil properties could also play a role. We designed an experiment aimed to disentangle the role of climate and (abiotic and biotic) soil properties in local adaptation of two common plant species. A grass (Holcus lanatus) and a legume (Lotus corniculatus), as well as their local soils, were reciprocally transplanted between three sites across an Atlantic-Continental gradient in Europe and grown in common gardens in either their home soil or foreign soils. Growth and reproductive traits were measured over two growing seasons. In both species, we found significant environmental and genetic effects on most of the growth and reproductive traits and a significant interaction between the two environmental effects of soil and climate. The grass species showed significant home site advantage in most of the fitness components, which indicated adaptation to climate. We found no indication that the grass was adapted to local soil conditions. The legume showed a significant home soil advantage for number of fruits only and thus a weak indication of adaptation to soil and no adaptation to climate. Our results show that the importance of climate and soil factors as drivers of local adaptation is species-dependent. This could be related to differences in interactions between plant species and soil biota. 相似文献
774.
Effects of four decades of fire manipulation on woody vegetation structure in Savanna 总被引:2,自引:0,他引:2
Higgins SI Bond WJ February EC Bronn A Euston-Brown DI Enslin B Govender N Rademan L O'Regan S Potgieter AL Scheiter S Sowry R Trollope L Trollope WS 《Ecology》2007,88(5):1119-1125
The amount of carbon stored in savannas represents a significant uncertainty in global carbon budgets, primarily because fire causes actual biomass to differ from potential biomass. We analyzed the structural response of woody plants to long-term experimental burning in savannas. The experiment uses a randomized block design to examine fire exclusion and the season and frequency of burn in 192 7-ha experimental plots located in four different savanna ecosystems. Although previous studies would lead us to expect tree density to respond to the fire regime, our results, obtained from four different savanna ecosystems, suggest that the density of woody individuals was unresponsive to fire. The relative dominance of small trees was, however, highly responsive to fire regime. The observed shift in the structure of tree populations has potentially large impacts on the carbon balance. However, the response of tree biomass to fire of the different savannas studied were different, making it difficult to generalize about the extent to which fire can be used to manipulate carbon sequestration in savannas. This study provides evidence that savannas are demographically resilient to fire, but structurally responsive. 相似文献
775.
Ruth M. Casper Simon N. Jarman Nicholas J. Gales Mark A. Hindell 《Marine Biology》2007,152(4):815-825
The diet of pinnipeds is most commonly inferred from morphologically diagnostic remains of prey in their scats. Although this
method can generate quantitative estimates of diet simply, important prey types may not always be detected. DNA-based methods
improve detection of prey in scats, but they are not quantitative. While some studies have combined morphological and DNA-based
methods, these have only assessed prey that are represented by their hard remains in scats. To overcome this bias, we apply
molecular and morphological analyses to the soft and hard portions of faecal samples respectively, to estimate the diet of
lactating Antarctic fur seals (Arctocephalus gazella) on Heard Island. The diet of this population is of particular interest because it is expanding rapidly and may rely to some
extent on mackerel icefish (Champsocephalus gunnari), which are subject to commercial fisheries. Based on results from morphological analysis and likely important prey types,
we tested for DNA remains of C. gunnari, myctophids and squid in faecal samples. The proportion of samples (n = 54) yielding no dietary information was reduced from around 25.9% using either method alone, to 9.3% when combined. Detection
of all prey types tested for was notably improved by integrating molecular and morphological data. Data from either method
alone would have underestimated the number of animals consuming C. gunnari by around 25.7%. Detection of multiple prey types in samples increased from 9.3% when using morphological analysis only,
to 33.3% when using DNA only, to 46.3% when using both methods. Taken in isolation, morphological data inferred that individual
seals consume either C. gunnari or myctophids, probably foraging in separate locations characteristic of those prey. Including molecular data demonstrated
that while this may be true of some individuals, many other seals consume a mixed diet of at least C. gunnari, myctophids and squid. This new approach of combining DNA-based and morphological analyses of diet samples markedly increased
the number of samples yielding dietary information, as well as increasing the amount of information attained from those samples.
Our findings illustrate the broad potential of this technique to improve insight into trophic interactions in marine ecosystems.
相似文献
Ruth M. CasperEmail: |
776.
Fisheries management is typically a complex problem, from both an environmental and political perspective. The main source of conflict occurs between the need for stock conservation and the need for fishing community well-being, which is typically measured by employment and income levels. For most fisheries, overexploitation of the stock requires a reduction in the level of fishing activity. While this may lead to long-term benefits (both conservation and economic), it also leads to a short-term reduction in employment and regional incomes. In regions which are heavily dependent on fisheries, short-term consequences of conservation efforts may be considerable. The relatively high degree of scientific uncertainty with respect to the status of the stocks and the relatively short lengths of political terms of office, generally give rise to the short-run view taking the highest priority when defining policy objectives. In this paper, a multi-objective model of the North Sea is developed that incorporates both long-term and short-term objectives. Optimal fleet sizes are estimated taking into consideration different preferences between the defined short-term and long-term objectives. The subsequent results from the model give the short-term and long-term equilibrium status of the fishery incorporating the effects of the short-term objectives. As would be expected, an optimal fleet from a short-term perspective is considerably larger than an optimal fleet from a long-run perspective. Conversely, stock sizes and sustainable yields are considerably lower in the long-term if a short-term perspective is used in setting management policies. The model results highlight what is essentially a principal-agent problem, with the objectives of the policy makers not necessarily reflecting the objectives of society as a whole. 相似文献
777.
Uptake of 137Cs and 40K was studied in seven native plant species of the Marshall Islands. Plant and soil samples were obtained across a broad range of soil 137Cs concentrations (0.08-3900 Bq/kg) and a narrower range of 40K soil concentrations (2.3-55 Bq/kg), but with no systematic variation of 40K relative to 137Cs. Potassium-40 concentrations in plants varied little within the range of 40K soil concentrations observed. Unlike the case for 40K, 137Cs concentrations increased in plants with increasing 137Cs soil concentrations though not precisely in a proportionate manner. The best-fit relationship between soil and plant concentrations was P = aSb where a and b are regression coefficients and P and S are plant and soil concentrations, respectively. The exponent b for 40K was zero, implying plant concentrations were a single value, while b for 137Cs varied between 0.51 and 0.82, depending on the species. For both 40K and 137Cs, we observed a decreasing concentration ratio (where concentration ratio=plant concentration/soil concentration) with increasing soil concentrations. For the CR values, the best-fit relationship was of the form CR = aSb/S = aSb(-1). For the 40K CR functions, the exponent b - 1 was close to - 1 for all species. For the 137Cs CR functions, the exponent b - 1 varied from -0.19 to -0.48. The findings presented here, aswell as those by other investigators, collectively argue against the usefulness of simplistic ratio models to accurately predict uptake of either 40K or 137Cs in plants over wide ranges of soil concentration. 相似文献
778.
779.
780.
More than 28 participants from 17 developing countries in Africa, Asia and the Pacific, Europe, Central and South America took part in the Seminar. International lecturers, including senior officials of financial institutions, served as resource persons for the Seminar and led the discussions. Representatives of government agencies, industry, universities, consultancy organizations and other international agencies were also present as observers. The Seminar framework was developed as a series of case study presentations, supplemented by lectures and discussions, which enabled participants to gain an appreciation of project finance requirements. The principal elements of the technical programme were Perspective, Concepts and Fundamentals of Project Analysis and Financial Evaluation, Project Finance Sources, Structure and Implementation, Identification, Minimization and Assignment of Risks, a Workshop Project, Case Studies and Developing Country Problems, Training Requirements and Methods of Implementation, and Recommendations for United Nations and Bilateral Cooperation with Developing Countries. 相似文献