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1.
Baboons (Papio spp.) are characterised by a large degree of variation in foraging behaviour and dietary composition. Previous analyses have suggested that much of this can be traced to differences in ecological conditions between sites. The proximate mechanism underlying these relationships is assumed to be mediated via the impact of climatic conditions on food availability, and ultimately the impact that this has on dietary composition. This paper examines these relationships more explicitly. Data from 15 baboon populations were used to assess the relationship between foraging variables and dietary composition. Only feeding time showed significant relationships with dietary composition, with percentage of time spent feeding decreasing with proportion of fruit in the diet, and increasing with the proportion of subterranean items. No relationships were found between diet composition and moving time or day journey length, although significant relationships were found between these variables and group size. The proportions of feeding time spent feeding on fruit, subterranean items and leaves were functions of the ecological conditions experienced by that population, although no relationships were found for the percentage of feeding time devoted to flowers or animal material. The relationships between the proportion feeding time spent on fruits, leaves and subterranean items and ecological variables could be best explained through understanding the way in which bush and tree level vegetation respond to the climatic environment and the impact this has on fruit availability. In this respect, temperature and seasonality are the key climatic parameters. This provides good support for the idea that the proximate mechanism underlying the relationship between foraging time and ecological variables is mediated via the impact of the climatic environment on vegetation structure and food availability. Similar factors have been proposed to explain much of the geographic variation in species diversity, suggesting that these relationships have far wider relevance and may account for much of the observed geographical variation in mammalian behaviour. 相似文献
2.
In this paper we compare foraging strategies that might be used by predators seeking prey in a patchy environment. The strategies differ in the extent to which predators aggregate in response to prey density. The approach to the comparison is suggested by the idea of evolutionarily stable strategies. A strategy is said to be evolutionarily stable if it cannot be invaded by another strategy. Thus we examine scenarios where a small number of individuals using one strategy are introduced into a situation where a large number of individuals using the other strategy are already present. However, our foraging models do not explicitly incorporate predator population dynamics, so we use net energy uptake as a surrogate for reproductive fitness. In cases where all of the patches visited by predators sustain prey populations, we find that for any pair of strategies one of them will have a higher net energy uptake than the other whether it is the resident or the introduced strain. However, which one is higher will typically depend on the total predator population, which is determined by the resident strain. If the predators leave prey densities high, the more aggregative strain will have the advantage. If the predators reduce prey densities to low levels the less aggregative strain will have the advantage. In cases where one strain of predators aggregates in response to prey density and the other does not, then there might be patches which do not contain prey but do contain (non-aggregating) predators. In those cases, there is the possibility that whichever strategy is used by the introduced strain will yield a higher energy uptake than that used by the resident strain. This suggests that if some patches are empty of prey then aggregative and non-aggregative strategies may be able to coexist. 相似文献
3.
Variation in learning abilities within populations suggests that complex learning may not necessarily be more adaptive than simple learning. Yet, the high cost of complex learning cannot fully explain this variation without some understanding of why complex learning is too costly for some individuals but not for others. Here we propose that different social foraging strategies can favor different learning strategies (that learn the environment with high or low resolution), thereby maintaining variable learning abilities within populations. Using a genetic algorithm in an agent-based evolutionary simulation of a social foraging game (the producer-scrounger game) we demonstrate how an association evolves between a strategy based on independent search for food (playing a producer) and a complex (high resolution) learning rule, while a strategy that combines independent search and following others (playing a scrounger) evolves an association with a simple (low resolution) learning rule. The reason for these associations is that for complex learning to have an advantage, a large number of learning steps, normally not achieved by scroungers, are necessary. These results offer a general explanation for persistent variation in cognitive abilities that is based on co-evolution of learning rules and social foraging strategies. 相似文献
4.
Animal and plant ecologists generally follow separate paths. This often leads to disjointed approaches to solving similar ecological problems. In the past 20 years, two related, but unconnected, research fields have undergone rapid development: modular demography, with its morphological and functional analysis of resource capture, until now basically the domain of plant ecology; and foraging theory, traditionally applied and developed in animal ecology. The results of recent research on the foraging strategies of ants and clonal plants, however, outline a general framework of functional parallels between both types of organisms that could link important aspects of animal and plant foraging ecology. 相似文献
5.
If baboon and macaque mating systems constitute a form of female defense polygyny, male mating strategies should be intrasexually selected and should vary in predictable ways with female defensibility, and demographic factors which affect the numbers of competing males per estrous female in populations. Substantial behavioral evidence exists for intrasexual selection of male mating strategies in baboons and macaques. Limited evidence also offers tentative support for theorybased predictions about the relationship between male mating strategy and female defensibility. Although male dominance rank generally predicts mating success, there are a number of factors which tend to increase the success of subordinate males above that expected from a simple dominance-based model of priority of access to mates. 相似文献
6.
We consider the effect of including energy costs on the optimal strategy for animals exploiting a depleting food resource. In the context of central place foraging this leads to the problem of what load size should be brought back to the central place. Two strategies are discussed: (i) maximize gross rate of energy delivery and (ii) maximize net rate of energy delivery. The optimal load size (or optimal patch time) for net maximizers is not always larger than for gross maximizers, as has been claimed. Instead, the difference in optimal load size has the same sign as the difference between metabolic rates of travelling and foraging. We point out that the influence of costs has not always been correctly incorporated in experimental tests of the theory. 相似文献
7.
Harvest rates and foraging strategies in Negev Desert gerbils 总被引:2,自引:0,他引:2
Ovadia Ofer; Ziv Yaron; Abramsky Zvika; Pinshow Berry; Kotler Burt P. 《Behavioral ecology》2001,12(2):219-226
We examined the foraging strategy and quantified the foragingtraits of two nocturnal rodent species, Allenby's gerbil (Gerbillusallenbyi) and the greater Egyptian sand gerbil (Gerbillus pyramidum).In the laboratory, both species used two distinct foragingstrategies: either they immediately consumed seeds found ina patch (seed tray); or they collected and delivered the seedsto their nest box for later consumption. Moreover, we founda transition in foraging strategy among individual G. allenbyi
under laboratory conditions; they all began by consuming theseeds on the tray and, after 7 days on average, switched tothe collecting strategy. By contrast, in the field both speciesused only one foraging strategy; they collected and deliveredthe seeds to their burrow or to surface caches for later consumption.Furthermore, G. allenbyi and G. pyramidum collected seeds atsignificantly higher rates in the field than in the laboratorybecause the seed encounter rates for both species were higherin the field. This suggests that in natural conditions, probablyinvolving predation risk and competitive pressure, gerbilsmust respond in two ways: (1) they must choose a foraging strategythat reduces predation risk by minimizing time spent feedingoutside their burrows; and (2) they must forage more efficiently.In the field, seed handling time of the larger species, G.
pyramidum, was shorter than that of the smaller one, G. allenbyi.This difference may give G. pyramidum an advantage when resourcelevels are high and when most of a forager's time is spent
handling seeds rather than searching for more seeds. Additionally,our field study showed that the seed encounter rate of G. allenbyiwas higher than that of G. pyramidum. This difference may giveG. allenbyi an advantage when resource levels are low and whensearching occupies most of the forager's time. The differentadvantages that each species has over the other, under differentconditions, may well be factors promoting their coexistenceover a wide range of resource densities. 相似文献
8.
R J Blumenschine 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》1991,334(1270):211-9; discussion 219-21
New evidence for the tissue types exploited by early hominids from carcasses possibly acquired through scavenging is derived from the larger mammal bone assemblages from FLK I, level 22 (Zinjanthropus floor), and FLKN levels 1 and 2 from Bed I, Olduvai Gorge, Tanzania. Published skeletal part profiles from the two archaeological sites are evaluated using (i) modern observations on the sequence by which carnivores consume carcass parts in order to assess the timing of hominid access to carcasses, and (ii) measurements of flesh and marrow yields to assess the tissue types sought and acquired. These results suggest that the maximization of marrow (fat) yields, not flesh (protein) yields, was the criterion shaping decisions about carcass processing. Because of evidence for density-dependent destruction of some flesh-bearing parts by scavengers of the hominid-butchered assemblages, however, it is uncertain whether carcass parts were transported and acquired by hominids in a largely defleshed condition. The results on tissue types acquired are combined with a discussion of predation risk, feeding competition and the equipment needs of carcass processing in an attempt to identify archaeological test implications of competing hypotheses for the socio-economic function of the earliest archaeological sites. 相似文献
9.
10.
S. W. Rissing 《Oecologia》1988,75(3):362-366
Summary Diets of desert seed-harvester ants Veromessor pergandei and Pogonomyrmex rugosus were studied for 3 years at two habitats where they are common and sympatric. Diets of the two species were similar, consisting mainly (87% of 23,913 seeds) of three annual plant species (Schismus arabicus, Plantago insularis, and Pectocarya recurvata). Diets converged following a drought in Winter/Spring 1984 which reduced seed production during this time. Foraging range of P. rugosus almost doubled following the drought while foraging range of V. pergandei remained constant. Neither ant species move their nests once established rendering them effectively sessile granivores. This limits the dietary options of a given colony and may explain interspecific dietary convergence. 相似文献
11.
《Saudi Journal of Biological Sciences》2017,24(2):268-275
In this work, a new plant-inspired optimization algorithm namely the hybrid artificial root foraging optimizion (HARFO) is proposed, which mimics the iterative root foraging behaviors for complex optimization. In HARFO model, two innovative strategies were developed: one is the root-to-root communication strategy, which enables the individual exchange information with each other in different efficient topologies that can essentially improve the exploration ability; the other is co-evolution strategy, which can structure the hierarchical spatial population driven by evolutionary pressure of multiple sub-populations that ensure the diversity of root population to be well maintained. The proposed algorithm is benchmarked against four classical evolutionary algorithms on well-designed test function suites including both classical and composition test functions. Through the rigorous performance analysis that of all these tests highlight the significant performance improvement, and the comparative results show the superiority of the proposed algorithm. 相似文献
12.
Wild isolates of Caenorhabditis elegans differ in their tendency to aggregate on food [1, 2]. Most quantitative variation in this behavior is explained by a polymorphism at a single amino acid in the G protein-coupled receptor NPR-1: gregarious strains carry the 215F allele, and solitary strains carry the 215V allele [2]. Although npr-1 regulates a behavioral syndrome with potential adaptive implications, the evolutionary causes and consequences of this natural polymorphism remain unclear. Here we show that npr-1 regulates two behaviors that can promote coexistence of the two alleles. First, gregarious and solitary worms differ in their responses to food such that they can partition a single, continuous patch of food. Second, gregarious worms disperse more readily from patch to patch than do solitary worms, which can cause partitioning of a fragmented resource. The dispersal propensity of both gregarious and solitary worms increases with density. npr-1-dependent dispersal is independent of aggregation and could be part of a food-searching strategy. The gregarious allele is favored in a fragmented relative to a continuous food environment in competition experiments. We conclude that the npr-1 polymorphism could be maintained by a trade-off between dispersal and competitive ability. 相似文献
13.
The Black-legged Kittiwake Rissa tridactyla is the most abundant gull species in the world, but some populations have declined in recent years, apparently due to food
shortage. Kittiwakes are surface feeders and thus can compensate for low food availability only by increasing their foraging
range and/or devoting more time to foraging. The species is widely studied in many respects, but long-distance foraging and
the limitations of conventional radio telemetry have kept its foraging behavior largely out of view. The development of Global
Positioning System (GPS) loggers is advancing rapidly. With devices as small as 8 g now available, it is possible to use this
technology for tracking relatively small species of oceanic birds like kittiwakes. Here we present the first results of GPS
telemetry applied to Black-legged Kittiwakes in 2007 in the North Pacific. All but one individual foraged in the neritic zone
north of the island. Three birds performed foraging trips only close to the colony (within 13 km), while six birds had foraging
ranges averaging about 40 km. The maximum foraging range was 59 km, and the maximum distance traveled was 165 km. Maximum
trip duration was 17 h (mean 8 h). An apparently bimodal distribution of foraging ranges affords new insight on the variable
foraging behaviour of Black-legged Kittiwakes. Our successful deployment of GPS loggers on kittiwakes holds much promise for
telemetry studies on many other bird species of similar size and provides an incentive for applying this new approach in future
studies. 相似文献
14.
15.
Root foraging strategies and soil patchiness in a humid savanna 总被引:1,自引:0,他引:1
In Lamto (Côte d'Ivoire), the savanna is a patchy environment as far as soil is concerned: tree clumps and termite mounds lead to higher nutrient contents than in the surrounding savanna. Mature Borassus aethiopum (Mart.) specimens are tall palm trees dominating the community, with aerial parts located out of these nutrient-rich patches.Palm root densities were compared under tree clumps and in the surrounding savanna, and were also sampled along transects between palm trees and nutrient-rich patches (two clumps and one mound). Palm root densities were far higher (up to 10 times) in the nitrogen-rich soil of both clumps and termite mounds than in the surrounding savanna. Evidence is given that palm trees are able to extend their root system as far as 20 m towards these nutrient-rich patches where they proliferate. These results point out a particular root foraging strategy, which is one of the first known for a woody perennial. They also provide new insights for understanding nitrogen cycling and savannas high rate of primary production. 相似文献
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17.
Environmental demands that require intensive search for mates, food and nest sites are correlated with efficient spatial memory in many mammalian and avian species. This convergence of evidence has led to the view that spatial memory, and the neurological structures associated with it, have been selected in niches that require memory for the location of goal objects. Whether such evolutionary demands are also correlated with nonspatial abilities that require flexible use of associations similar to those required for spatial memory has not been well studied. In addition, correlations between niche types and the use of spatial or nonspatial memory have not been investigated in nonmammalian, nonavian taxa. In this study, we investigated the relationship between foraging strategies and performance on two tasks, one spatial and the other nonspatial, in congeneric lizard species: Acanthodactylus boskianus, an active forager that collects clumped sedentary prey, Acanthodactylus scutellatus, a sit-and-wait predator that collects distributed mobile prey. The two species did not differ in their performance of a spatial memory task, but A. boskianus, the active forager, performed better on the reversal of a visual discrimination, a nonspatial task. These findings question the generality of the spatial adaptation model for vertebrates. We present the pliancy hypothesis, which we developed to account for these results. Copyright 1999 The Association for the Study of Animal Behaviour. 相似文献
18.
J A Beecham 《Bio Systems》2001,61(1):55-68
A model was developed to explain one mechanism whereby differential optimal foraging strategies can occur between species as a result of selection for competition avoidance. This is the primary requirement for niche differentiation to evolve without a difference in the underlying foraging ability or morphology. The model used an individual-based patch choice mechanism, whereby herbivores move from patch to patch seeking food with the highest nutrient intake characteristics. The choice of patch was governed by a parameter, mu, which determined to what extent information in the landscape at different distances from the herbivore was used by it to make foraging decisions. A genetic algorithm was used to optimise the value, mu, in a complex landscape. The value of mu quickly converged to a single value with stabilising selection occurring when there was only a single species foraging. When there was a competing species with a fixed value of mu, the value of mu evolved to be above or below the mean for the single species mean depending on whether the value of mu for the competitor was below, or above the single-species mean, respectively. This was indicative of niche segregation. However mu tended to vary unstably over time when allowed to vary simultaneously in both species, although there was evidence for interaction between the two values. These results indicate that there can be a competitive advantage in choosing a cognitive strategy that is complementary to that used by other species. 相似文献
19.
Claudia Sick Alecia J. Carter Harry H. Marshall Leslie A. Knapp Torben Dabelsteen Guy Cowlishaw 《Biology letters》2014,10(7)
Strong social bonds can make an important contribution to individual fitness, but we still have only a limited understanding of the temporal period relevant to the adjustment of social relationships. While there is growing recognition of the importance of strong bonds that persist for years, social relationships can also vary over weeks and months, suggesting that social strategies may be optimized over shorter timescales. Using biological market theory as a framework, we explore whether temporal variation in the benefits of social relationships might be sufficient to generate daily adjustments of social strategies in wild baboons. Data on grooming, one measure of social relationships, were collected from 60 chacma baboons (Papio ursinus) across two troops over a six month period. Our analyses suggest that social strategies can show diurnal variation, with subordinates preferentially grooming more dominant individuals earlier in the day compared with later in the day. These findings indicate that group-living animals may optimize certain elements of their social strategies over relatively short time periods. 相似文献