共查询到20条相似文献,搜索用时 31 毫秒
1.
Weissburg M.J. Dusenbery D.B. Ishida H. Janata J. Keller T. Roberts P.J.W. Webster D.R. 《Environmental Fluid Mechanics》2002,2(1-2):65-94
This report describes the results of a multidisciplinary study of turbulent chemical plume tracking of blue crabs and autonomous agents. The study consists of a coordinated investigation of animal behavior, fluid mechanics, strategy simulations, and chemical sensing. The objective is to provide a comprehensive understanding of chemical plume tracking in a single biological system and to prescribe strategies that are effective for autonomous agents. The consensus of the study is that spatial variation in the plume, measured by sampling at multiple locations simultaneously, yields information that is useful for plume tracking. Behavioral investigations reveal that blue crabs demonstrate the ability to detect the chemical plume and use lateral movements to avoid losing contact with the odor. Blue crabs move rapidly towards the source, strongly suggesting that temporal comparisons of odor properties are not employed during navigation. Analysis of the concentration fields reveals that a spatial correlation between spanwise-separated sensors indicates the relative direction of the plume centerline over short time periods provided the sensor spacing is scaled appropriately relative to the plume. Similarly, simulations of tracking strategies reveal an optimal separation for the sensors at a distance roughly equal to the plume width; both smaller and larger sensor spans degrade tracking performance. The simulations further reveal an optimal sensor size above which the fine details of the concentration distribution are obscured and below which there is insufficient contact with the odor to enable effective navigation. Finally, analysis of the chemical signal shows that the frequency dependent correlation function between two (or more) sensors indicates the relative position of the source. 相似文献
2.
Xuying Ma Ian Longley Jennifer Salmond Jay Gao 《Frontiers of Environmental Science & Engineering》2020,14(3):44
3.
Recent attempts to integrate function and mechanism have resulted in an appreciation of the relevance of forager psychology
to understanding the functional aspects of foraging behaviour. Conversely, an acknowledgement of the functional diversity
of learning mechanisms has led to greater understanding of the adaptive nature of cognition. In this paper, we present data
from three experiments suggesting that noisy miner birds use different cognitive strategies when searching for foods with
different distributions. When searching for nectar, an immobile, readily depleted resource, birds spontaneously attend to
fine-scale spatial information and use a spatial memory-based strategy that is efficient in a novel context and largely resistant
to disruptions to movement. When searching for invertebrates, a mobile, clumped and cryptic resource, birds employ a strategy
whose efficiency increases with increased task familiarity, is vulnerable to disruptions to their movement and may rely more
on memory for movement rules than memory for location information. Previous reports of adapted cognition have reported performance
differences between species (for example, better spatial cognitive performance in storing versus non-storing birds). Ours
is the first study to demonstrate that differences in cognitive strategy (as opposed to just enhanced performance) occur within
a single species in different foraging contexts. As well as providing an example of how specially adapted cognitive mechanisms
might work, our data further emphasise the importance of jointly considering functional and mechanistic aspects to fully understand
the adaptive complexities of behaviour. 相似文献
4.
A variety of animals use olfactory appendages bearing arrays of chemosensory neurons to detect chemical signatures in the water or air around them. This study investigates how particular aspects of the design and behavior of such olfactory appendages on benthic aquatic animals affect the patterns of intercepted chemical signals in a turbulent odor plume. We use virtual olfactory `sensors' and `antennules' (arrays of sensors on olfactory appendages) to interrogate the concentration field from an experimental dataset of a scalar plume developing in a turbulent boundary layer. The aspects of the sensors that we vary are: (1) The spatial and temporal scales over which chemical signals arriving at the receptors of a sensor are averaged (e.g., by subsequent neural processing), and (2) the shape and orientation of a sensor with respect to ambient water flow. Our results indicate that changes in the spatial and temporal resolution of a sensor can dramatically alter its interception of the intermittency and variability of the scalar field in a plume. By comparing stationary antennules with those sweeping through the flow (as during antennule flicking by the spiny lobster, Panulirus argus), we show that flicking alters the frequency content of the scalar signal, and increases the likelihood that the antennule encounters peak events. Flicking also enables a long, slender (i.e., one-dimensional) antennule to intercept two-dimensional scalar patterns. 相似文献
5.
Individual bees often restrict their visits to only a few species out of the multitude of available plants. This flower constancy
is likely caused by limitations of memory for motor patterns, sensory stimuli, or reward levels. Here we test the implications
of sensori-motor learning and memory for flower constancy. Artificial “flowers” with two distinct “morphologies” were used,
so that in each flower type, a different motor pattern was needed to reach the nectar. As in natural flowers, these morphological
types were associated with sensory signals (blue and yellow color stimuli). Bees which learned only a single task were more
efficient in several ways than those which had learned two: they made fewer errors, had shorter flower handling times, took
shorter times to correct errors, and transitions between flowers were initially more rapid. For bees which had learned two
tasks, performance depended strongly on the training schedule: if each task was learned with blocked trials, the memory for
the second appeared to interfere with that for the first. Interference affected only the association between flower signal
and motor pattern, not the motor pattern itself. This was not the case if bees were trained for both tasks with alternating
trials. In that case, bees rapidly learned both tasks, albeit with worse saturation levels than bees which had learned only
one. Bees transferred the experience gained on one task to a second task: their initial performance on the second task was
better than their initial performance on the first. On the other hand, performance on the second task in the saturation level (in which bees no longer improve their efficiency) was worse than on the first task (negative transfer). In the saturation
phase, performance did not directly depend on switch frequency, but on whether the bee had one or two options in memory. Thus,
while bees would become proficient at two tasks more quickly if their acquisition phase included switches, such switches had
no measurable effect in the saturation phase. The implications of these findings for foraging are discussed using modern learning
theory.
Received: 4 April 1997 / Accepted after revision: 8 August 1997 相似文献
6.
《Journal of Environmental Economics and Management》1987,14(3):304-312
We compare pesticide use and total cost of mosquito control under integrated and chemical control strategies using data from the San Joaquin Valley, California. The analysis shows that the use of biological control allows substantial cuts in chemical treatments, inspection effort and control costs required to meet mosquito control targets. Thus, integrated pest management in this case is clearly superior economically as well as preferable from an ecological perspective. These results suggest the desirability of public action to augment mosquitofish supplies, the lack of which currently constitutes a key obstacle to broader application of the integrated strategy. 相似文献
7.
T. Robinet E. Réveillac M. Kuroki J. Aoyama K. Tsukamoto M. W. Rabenevanana P. Valade P.-A. Gagnaire P. Berrebi E. Feunteun 《Marine Biology》2008,154(3):453-463
A total of 4,172 freshwater eels have been collected by electrofishing in upper estuaries from Madagascar (East coast), Mascarene
(Réunion and Mauritius Is.), Comoros (Mayotte Is.) and Seychelles (Mahé and Praslin Is.) Archipelagos, between October 2003
and February 2006. Eel species composition in the sampling stations was contrasted between eastern Madagascar (Anguilla mossambica 96.0%, A. marmorata 3.9% and A. bicolor bicolor 0.2%), the Comoros (A. marmorata 56.1% and A. bicolor bicolor 43.9%), the Mascarene (A. marmorata 91.4%, A. bicolor bicolor 5.4% and A. mossambica 3.2%) and the Seychelles Archipelagos (A. bicolor bicolor 100.0%). This gradient in species composition, even concerning the short time-range of our sampling, argued for separate
migration routes between species. A total of 168 eels were aged by reading their otolith microstructure, and otolith growth
rates were calculated from pre-leptocephalus stage (post-hatching) to metamorphosis, until freshwater check. For all species,
mean otolith growth rate (OGR) was related to specific migration routes: A. bicolor bicolor is distributed in the lowest latitudes and showed the highest OGR during leptocephalus stage, whereas A. mossambica, endemic of the Malagasy area, has the most southern distribution and showed the lowest OGR. OGR during leptocephalus stage
was negatively correlated to the leptocephalus stage duration, showing a decrease of global metabolism with time, classical
in leptocephali. This relationship was found significant for A. marmorata and A. mossambica, probably because all these larvae crossed successively the same environments, but not for A. bicolor bicolor, probably because their larvae crossed different pelagic environments, opening the hypothesis of larvae from different origins. 相似文献
8.
Tarik Hadzibeganovic Francisco W. S. Lima Dietrich Stauffer 《Behavioral ecology and sociobiology》2014,68(7):1059-1072
We study the effects of working memory capacity and network rewiring probability on the evolution of cooperation in the standard and modified versions of an agent-based model of tag-mediated altruism. In our evolutionary model, computational agents populate a large complex network, engage into multiplayer Prisoner’s Dilemma-like interactions, and reproduce sexually. Agents carry discernible phenotypic traits subject to mutation, memorize their own experiences, and employ different strategies when interacting with different types of co-players. Choices made are selected from a pool of two conditional and two unconditional strategies, depending on the available memory contents and phenotypic similarity among interactors. For the dominating strategy in our standard model version, we found a strong dependence of cooperation on network structure and a weak one on memory, whereas in the modified version, the structural effect was weaker than that of memory. Most importantly, we found that the previously reported decline of cooperation in memory-based models, typically observed at a high memory capacity, is now prevented with the help of tags. This suggests that the evolutionary advantages of memory capacity limits may be far more complex than previously assumed. For much smaller systems, we observed a quasi-symmetric alternation of the two winning groups of strategists. This result provides an example of ingroup biased interactions that are characterized by bursts of intra-tag cooperation interspersed with periods of unconditional transient altruism. Such switches of strategies may represent a boosting mechanism necessary for the emergence and stability of global altruism in its early evolutionary stages. 相似文献
9.
We present a cellular automaton that simulates the interaction between a host tree and multiple potential mycorrhizal symbionts and generates testable hypotheses of how processes at the scale of individual root tips may explain mycorrhizal community composition. Existing theoretical biological market models imply that a single host is able to interact with and select from multiple symbionts to organize an optimal symbiont community. When evaluating the tree–symbiont interaction, two scales must be considered simultaneously: the scale of the entire host plant at which carbon utilization and nutrient demands operate, and the scale of the individual root tip, at which colonization and carbon-nutrient trade occurs. Three strategies that may be employed by the host tree for optimizing carbon use and nutrient acquisition through mycorrhizal symbiont communities are simulated: (1) carbon pool adjustment, in which the plant controls only the total amount of carbon to be distributed uniformly throughout the root system, (2) symbiont selection, wherein the plant opts either for or against the interaction at each fine root tip, and (3) selective carbon allocation, wherein the plant adjusts the amount of carbon allocated to each root tip based on the cost of nutrients. Strategies were tested over various nutrient availabilities (the amount of inorganically and organically bound nutrients). Success was defined on the basis of minimizing carbon expended for nutrient acquisition because this would allow more carbon to be utilized for growth and reproduction. In all cases, the symbiont selection and selective carbon allocation strategies were able to meet the nutritional requirements of the plant, but did not necessarily optimize carbon use. The carbon pool adjustment strategy is the only strategy that does not operate at the individual root tip scale, and the strategy was not successful when inorganic nutrients were scarce since there is no mechanism to exclude suboptimal symbionts. The combination of the symbiont selection strategy and the carbon pool adjustment resulted in optimal carbon use and nutrient acquisition under all environmental conditions but result in monospecific symbiont assemblages. On the other hand, the selective carbon allocation strategy is the only strategy that maintained successful, multi-symbiont communities. The simulations presented here thus imply clear hypotheses about the effect of nutrient availability on symbiont selection and mycorrhizal community richness and composition. 相似文献
10.
Duccio Lambardi Francesca R. Dani Stefano Turillazzi Jacobus J. Boomsma 《Behavioral ecology and sociobiology》2007,61(6):843-851
Some social parasites of insect societies are known to use brute force when usurping a host colony, but most use more subtle
forms of chemical cheating either by expressing as few recognition cues as possible to avoid being recognized or by producing
similar recognition cues to the host to achieve positive discrimination. The former “chemical insignificance” strategy represents
a more general adaptive syndrome than the latter “chemical mimicry” strategy and is expected to be characteristic of early
evolutionary stages of social parasitism. We tested this hypothesis by experimentally analyzing the efficiency by which Acromyrmex echinatior leaf-cutting ants recognize intruding workers of the incipient social parasite Acromyrmex insinuator. The results were consistent with the parasite being “chemically insignificant” and not with the “chemical mimicry” hypothesis.
Gas chromatography–mass spectrometry analysis of cuticular hydrocarbon profiles showed that social parasite workers produce
significantly fewer hydrocarbons overall and that their typical profiles have very low amounts of hydrocarbons in the “normal”
C29–C35 range but large quantities of unusually heavy C43–C45 hydrocarbons. This suggests that the C29–C35 hydrocarbons are
instrumental in normal host nestmate recognition and that the C43–C45 compounds, all of which are dienes and thus more fluid
than the corresponding saturated compounds, may reinforce “chemical insignificance” by blurring any remaining variation in
recognition cues. 相似文献
11.
Summary. Easy bleeding is a phenomenon discovered in some tenthredinid insects which possess a particularly low mechanical resistance of the integument, leading under mechanical stress to haemolymph exudation. It has a defensive effect against ants and wasps through harmful plant compounds which are sequestered in the haemolymph. Here we describe etho-ecological and some chemical aspects of the defence of easy bleeders and specify the range of predators to which easy bleeding might be effective. Beside a high haemolymph deterrence associated with low integument resistance across sawfly species, we also detected toxicity of the haemolymph of some species to workers of the ant Myrmica rubra. The behaviour of easy bleeders is to move slowly and, once disturbed, to become motionless, thereby probably impeding the tendency of a predator to attack. This behaviour had no beneficial effect for easy bleeders when attacked by the predatory bug Podisus maculiventris. Bugs could successfully and without harm prey on sawfly larvae without evoking easy bleeding. For the easy bleeder Athalia rosae, host plants with different secondary metabolite profiles, and, consequently, changes in haemolymph chemistry only slightly affected the feeding behaviour of the bugs. To test the effectiveness of easy bleeding towards a vertebrate predator, easy bleeders were offered to birds, Sturnus vulgaris. The body colouration of the sawfly larvae was of prime importance in determining the predators response when testing birds in a group. It is likely that easy bleeding is a defence strategy directed primarily towards foraging insects with biting-chewing mandibles and that it is much less active towards predatory insects with piercing-sucking mandibles as well as birds. The involvement of chemical and/or physical cues in the strategy is discussed with respect to these types of predators. 相似文献
12.
Sabine Bauer Volker Witte Melanie Böhm Susanne Foitzik 《Behavioral ecology and sociobiology》2009,64(1):45-56
Ant social parasites use chemical warfare to facilitate host colony takeover, which is a critical but recurring step in their
life cycle. Many slave-making ants use the secretion of the Dufour gland to manipulate host behaviour during parasitic nest
foundation and slave raids. Harpagoxenus sublaevis applies this chemical weapon onto defending Leptothorax host workers, which elicits deadly fights amongst them. Host species are expected to evolve counter-adaptations against this
behavioural manipulation and in this study we investigated the geographic structure of this co-evolving trait. We compared
the effectiveness of the parasitic gland secretion from different H. sublaevis populations in host colonies from various sites and analysed the occurrence of local adaptation. The two host species L. muscorum and L. acervorum generally showed different responses to the parasites’ chemical weapon: L. acervorum attacked nestmates treated with Dufour gland secretion, while L. muscorum workers fled. Flight, instead of intraspecific fights, is an adaptive host reaction as it results in fewer host fatalities
during raids. Beside interspecific host differences, we found a geographic mosaic of host resistance: parasites from a German
population strongly manipulated the behaviour of both sympatric Leptothorax populations. Russian or Italian hosts instead did not react with intracolonial aggression, but fled when confronted with
the gland secretion of their sympatric parasite. Not only variation in host resistance explains differences in the effectiveness
of the parasitic gland secretion but also interpopulational differences in its chemical composition, which were revealed by
gas chromatography and mass spectrometry. 相似文献
13.
土壤生态系统中黑碳研究的几个关键问题 总被引:2,自引:0,他引:2
因人类活动的影响,全球大气C02浓度自1750年以来呈现逐步上升的趋势。农业生产活动与气候变化紧密相关,因土地利用方式的改变以及高度集约化的粮食、食物生产等农业活动都有可能增加CO2等温室气体的排放。如何遏制和减少大气中的CO2浓度是当前的热点问题,黑碳这一物质形式有可能为这一问题的缓解或解决提供新途径。生物质黑碳是生物质材料在低氧或无氧状态下经热裂解而形成的一种富含碳元素的有机连续体,其中碳(C)元素的含量高达70%-80%,并且大多以稳定的芳香环形式而存在。人类生存环境中所形成黑碳的80%以上最终都要归于土壤,且由于其较强的抗分解能力而长期滞留于土壤环境中。利用黑碳的这些特性及其碳封存能力,实施积极而有效的土壤管理措施,有可能增加土壤生态系统中的碳储存,从而为人类社会应对全球气候变化提供新的机遇。在文献资料调研的基础上,描述了土壤中黑碳的来源及其增加土壤碳储存、减缓陆地生态系统碳循环的潜力;阐释了量化土壤中黑碳的重要性以及精确测定土壤黑碳含量的关键所在;揭示了黑碳在土壤环境中的稳定性,探讨了外源黑碳与土壤本体有机碳的相互作用关系,并分析了黑碳对土壤温室气体排放的影响及其不确定性。揭示这些问题有助于客观评价黑碳能否作为一个有效的土壤有机碳库,也益于明确黑碳在全球碳循环以及中国农业减排过程中的作用与地位。 相似文献
14.
Soil management for sustainable crop disease control: a review 总被引:2,自引:0,他引:2
Excessive use of agrochemicals in conventional crop management has caused serious environmental and health problems including
loss of biodiversity and human disorders. A number of chemical biocides have shown complex chronic effects such as change
in endocrine functions and immune systems. Application of different chemical biocides to the soil and plants have increased
substantially over the last five decades. Total consumption of chemical fertilizers worldwide increased tenfold from 1950
to 2000. This is also true for chemical biocides with its annual current use of 3 billion l and a value of 30 billion dollars.
There are ample evidences indicating that plants which grow in rich soil associated with N-P-K availability are prone to pests
and diseases. Managing and exploiting soil environmental conditions as part of an integrated control strategy can make a significant
contribution to agricultural sustainability and environmental quality. Application of organic matter and practises which increase
the total microbial activity in the soil might enhance general suppression of pathogens by increasing competition for nutrients.
Choice of crops in rotation with plants less susceptible to specific pathogens causes a decline in population due to natural
mortality and the antagonistic activities of co-existent root zone microorganisms. Plants growing in disease-suppressive soil
resist diseases much better than in soils with low biological diversity. Understanding the effect of soil environmental factors
on plant disease incidence and the best crop management strategies to prevent, avoid, escape and control diseases were the
aims of this literature review. This article comprises the main topics on soil fertility associated with N-P-K and other macro-
and micro nutrients, and also soil pH, structure and texture, organic matter and microbial reserves, describes the use of
various crop management practises which reduce the incidence of plant diseases. 相似文献
15.
Multi-Beam Echo Sounders are often used for classification of seabed type, as there exists a strong link between sonar backscatter and sediment characteristics of the seabed. Most of the methods for seabed classification from MBES backscatter create a highly-dimensional data set of statistical features and then use a combination of Principal Component Analysis and k-means clustering to derive classes. This procedure can be time consuming for contemporary large MBES data sets with millions of records. This paper examines the complexity of one of most commonly used classification approaches and suggests an alternative where feature data set is optimised in terms of dimensionality using computational and visual data mining. Both the original and the optimised method are tested on an MBES backscatter data set and validated against ground truth. The study found that the optimised method improves accuracy of classification and reduced complexity of processing. This is an encouraging result, which shows that bringing together methods from acoustic classification, visual data mining, spatial analysis and remote sensing can support the unprecedented increases in data volumes collected by contemporary acoustic sensors. 相似文献
16.
Concei??o Juana Fortes óscar Ferreira Paulo A. Silva Theo Moura Rui Capit?o Luís Amante Michalis Vousdoukas Maria Bezerra 《Journal of Coastal Conservation》2012,16(4):461-472
In the framework of a research project entitled ??BRISA??BReaking waves and Induced SAnd transport??, a methodology was devised to characterize the waves joining together in-situ measurements and numerical wave propagation models. With this goal in mind, a number of in-situ measurements were made, for selected positions in front of Praia de Faro (South Portugal), during four days (25th to 28th March, 2009) by using different types of equipments (e.g., resistive wave gauges, pressure sensors, currentmeters and a new prototype pore pressure sensor using optical fibre). Wave records were obtained simultaneously offshore (at a water depth of 11.7?m below mean sea level, MSL) and at the surf and swash zones. The data processing and analysis were made by applying classical time domain techniques. Numerical simulations of the wave propagation between offshore and inshore for the measurement period were performed with two numerical models, a 1D model based on linear theory and a nonlinear Boussinesq-type model, COULWAVE, both forced by the measured offshore wave conditions of 27th March 2009. Comparisons between numerical results and field data for the pressure sensors placed in the surf and swash zones were made and discussed. This approach enables to evaluate the performance of those models to simulate those specific conditions, but also to validate the models by gaining confidence on their use in other conditions. 相似文献
17.
Strategies of female mate choice: A theoretical analysis 总被引:15,自引:0,他引:15
Anthony C. Janetos 《Behavioral ecology and sociobiology》1980,7(2):107-112
Summary Females of many species face a difficult sampling problem while searching for a mate. How do they find the best male possible when the constraints of time, memory, and mobility prevent them from visiting all the males in the population?Five possible solutions are examined: random mating a fixed-threshold criterion, a fixed-threshold with last-chance option, an optimal one-step decision strategy, and the best-of-n-males strategy. Random mating is the worst strategy whenever the female gets more than one chance to mate. The two fixed-threshold strategies approach equal effectiveness as n increases but are always below the optimal one-step decision strategy. However, the best-of-n-males strategy always yields the highest expectation of fitness in a mate. The difference is especially great when n5.Plotting the average fitness of males chosen vs n, the number of males examined, yields a negatively accelerating curve. Since the cost of searching will be an increasing function of n, the two curves can be combined to yield an optimum n: the point where the difference between the curves is greatest.The one field study (Brown 1978) that addresses these problems in detail reveals that female mottled sculpins choose males on a relative, rather than absolute, basis, as theory suggests they should. 相似文献
18.
Alexandra Bottcher Jorge Paulo Zolin Flávia Nogueira-de-Sá José Roberto Trigo 《Chemoecology》2009,19(1):63-66
The most frequently investigated defence mechanism among larvae of tortoise beetles is protection by faecal shields, which
generally present chemicals that are directly sequestered and/or modified from larval host-plants. In the present work we
investigate the tortoise beetle Chelymorpha reimoseri that feeds on the leaves of Ipomoea carnea fistulosa (Convolvulaceae), seeking for the importance of this mechanism to their larvae. We show that 4th instar larvae suffer low
predation regardless of the presence of shields in field and laboratory bioassays with ants and chicks. Chloroform extract
from larvae without shields provided high protection against predation as shown in bioassays in the field, as well as against
chicks, suggesting that C. reimoseri does not rely on the shield for protection. The aqueous extract of the shields did not show activity in such bioassays. The
compounds responsible for this protection have yet to be identified, and it remains an open question as to whether they are
sequestered from the host plant or de novo biosynthesized. This is the first record of chemical defence in cassidine beetles
without the need for faecal shields. These findings indicate that more attention should be paid to chemicals present in the
tissues of larvae and/or adults of tortoise beetles; the protective compounds sequestered from host plants or de novo biosynthesized
can provide an alternative or complementary strategy against predation in these insects. 相似文献
19.
Austen W. Head Johanna S. Hardin Stephen C. Adolph 《Environmental and Ecological Statistics》2012,19(2):127-137
Estimates of animal performance often use the maximum of a small number of laboratory trials, a method which has several statistical disadvantages. Sample maxima always underestimate the true maximum performance, and the degree of the bias depends on sample size. Here, we suggest an alternative approach that involves estimating a specific performance quantile (e.g., the 0.90 quantile). We use the information on within-individual variation in performance to obtain a sampling distribution for the residual performance measures; we use this distribution to estimate a desired performance quantile for each individual. We illustrate our approach using simulations and with data on sprint speed in lizards. The quantile method has several advantages over the sample maximum: it reduces or eliminates bias, it uses all of the data from each individual, and its accuracy is independent of sample size. Additionally, we address the estimation of correlations between two different performance measures, such as sample maxima, quantiles, or means. In particular, because of sampling variability, we propose that the correlation of sample means does a better job estimating the correlation of population maxima than the estimator which is the correlation of sample maxima. 相似文献
20.
A test of the producer-scrounger foraging game in captive flocks of spice finches,Loncbura punctulata 总被引:2,自引:0,他引:2
Luc-Alain Giraldeau Catherine Soos Guy Beauchamp 《Behavioral ecology and sociobiology》1994,34(4):251-256
Group foraging allows the co-existence of a strategy (producer) that involves searching for food, and its alternative (scrounger) exploiting the food of the producer. The use of producer and scrounger strategies has been modelled as an alternative-option scramble which assumes strong negative frequency-dependence of the scrounger's pay-offs. We tested this assumption in a flock feeding situation by manipulating the proportion of scroungers in flocks of spice finches, Lonchura punctulata. In a first experiment we found that: (1) the food intake of scroungers, and to a lesser extent producers, was negatively affected by an increase in the proportion of scroungers; (2) the food intake of producers and scroungers was equal when the proportion of scroungers was small, suggesting that producers, who exploited 35.4% of their patches by scrounging were opportunistically adjusting their use of the strategies until the pay-offs equalized. In a second experiment we tested whether finches could vary their use of the two strategies in response to changes in foraging conditions brought about by an increase in the cost of producing. As predicted by the game, finches reduced their use of the producer strategy and increased their use of the scrounger strategy when the cost of producing increased. These results suggest that spice finches can alter their allocation to each foraging alternative by experience and that the producer-scrounger game is a realistic model for predicting group foraging decisions.
Correspondence to: L.-A. Giraldeau 相似文献