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581.
Genetic diversity might increase the performance of social groups by improving task efficiency or disease resistance, but direct experimental tests of these hypotheses are rare. We manipulated the level of genetic diversity in colonies of the Argentine ant Linepithema humile, and then recorded the short-term task efficiency of these experimental colonies. The efficiency of low and high genetic diversity colonies did not differ significantly for any of the following tasks: exploring a new territory, foraging, moving to a new nest site, or removing corpses. The tests were powerful enough to detect large effects, but may have failed to detect small differences. Indeed, observed effect sizes were generally small, except for the time to create a trail during nest emigration. In addition, genetic diversity had no statistically significant impact on the number of workers, males and females produced by the colony, but these tests had low power. Higher genetic diversity also did not result in lower variance in task efficiency and productivity. In contrast to genetic diversity, colony size was positively correlated with the efficiency at performing most tasks and with colony productivity. Altogether, these results suggest that genetic diversity does not strongly improve short-term task efficiency in L. humile, but that worker number is a key factor determining the success of this invasive species.Communicated by L. Sundström 相似文献
582.
We study interactions between resource distributions, grouping, and diet development in foragers who learn by trial-and-error. We do this by constructing an individual-based model where individuals move and forage in groups in a 2-D space with high resource diversity and learn what to eat. By comparing diet development in different resource distributions, and in gregarious and solitary individuals, we elucidate how these factors affect patterns of diet variation. Our results indicate that different resource distributions have profound effects on learning opportunities, and thereby lead to contrasting phenomena. In uniform environments, local resource depletion by gregarious individuals, in interaction with learning, leads to diet differentiation. In patchy environments, grouping leads to enhanced diet overlap within groups and leads to differences in diet between groups. Surprisingly, mixed environments can generate all these phenomena simultaneously. Our results predict relationships between diet variation, trial-and-error learning, and resource distributions. The phenomena we describe are not evolved strategies, but arise spontaneously when groups of individuals learn to forage in certain resource distributions. This suggests that describing diet specialization or diet homogenization as the result of behavioral strategies may not always be justified. 相似文献
583.
Reproductive skew theory has been an important component of efforts to design a unifying theory of social evolution, as it aims to explain patterns of reproductive partitioning in animal societies as a function of relatedness, group productivity, fighting ability and ecological constraints on independent reproduction. However, empirical tests of the theory have often provided ambiguous or non-conclusive results, assumptions behind alternative models have rarely been tested, and theoretical elaborations have shown the limitations of the reproductive skew approach. Here we analyse a relatively large sample of colonies of the Stenogastrine wasp Parischnogaster mellyi with a powerful set of DNA microsatellite markers. We show that various apparently stable forms of social organisation co-exist in a single population, and that sharing of reproduction between related and unrelated egg-laying females occurs in some of the nests. Present reproductive skew theory appears to be at best partly sufficient to account for the observed complexity of social organisation. The observed patterns of colony composition and reproductive sharing are weakly consistent with the hypothesis of reproductive transactions, while they can more parsimoniously be explained by the life-history characteristics of the species.Communicated by R.F.A. Moritz 相似文献
584.
Sonia Kaushik Bandhana Katoch Vidyanand Nanjundiah 《Behavioral ecology and sociobiology》2006,59(4):521-530
The Dictyostelid or cellular slime moulds (CSMs) are soil amoebae with an asexual life cycle involving social behaviour and
division of labour. The most obvious distinction is between ‘germ line’ or pre-spore cells, which survive, and ‘somatic’ or
pre-stalk cells, which eventually die. A plausible hypothesis to explain the apparent altruism of pre-stalk cells is that
it is directed at clonal relatives. We have tested this hypothesis by comparing indices of altruistic behaviour between clonal
and chimeric (genetically heterogeneous) social groups. The groups were generated by mixing amoebae belonging to distinguishable
strains of Dictyostelium giganteum. The amoebae of one strain do not aggregate at all when mixed with any of three other strains and aggregate poorly with a
fourth. Among the latter, co-aggregation occurs but is followed by varying extents of sorting out. At times, two strains form
separate fruiting bodies; in other cases, they remain together but are clustered in clonal groups within a single chimeric
structure. Our expectation was that the allocation of cells to the stalk pathway would be higher, and to the spore pathway
lower, in clonal social groups than in chimeras. The expectation was not always fulfilled. In addition, three strains could
be arrayed in a linear rank order in terms of the relative efficiencies of spore-formation in binary mixtures; but when all
three were mixed, they were equally efficient. More than overall genetic similarity, cell fate in a chimera seems to result
from complex non-linear interactions based on epigenetic differences. 相似文献
585.
M. M. Webster J. Goldsmith A. J. W. Ward P. J. B. Hart 《Behavioral ecology and sociobiology》2007,62(2):273-280
The structure of social animal groups can be dynamic, characterized by high rates of group fission and fusion. Despite this,
group composition is often well ordered by factors such as species, body size and by numerous other phenotypic traits. Research
in shoaling fishes has revealed that individuals refine group membership decisions still further and are capable of assimilating
chemical cues pertaining to recent habitat and prey use by prospective group mates, preferring to associate with others whose
recent resource use history closely matches their own. In this study, we firstly examined the dynamics of the formation and
breakdown of these preferences, revealing that they can be acquired and replaced in a matter of just a few hours. Using such
cues enables individuals to accurately assess the resource use of conspecifics, allowing them to indirectly sample the local
environment while reducing the chances of acquiring outdated information that can precipitate maladaptive behaviors. Secondly,
we found that shoals composed of individuals with shared recent habitat use history were more cohesive compared to those where
the constituent individuals differed in recent habitat use. Increased shoal cohesion may reduce predation risk, and could
enhance the ability of individuals to detect and use social information. 相似文献
586.
Reintroduction programs for conservation purposes suffer from low post-release survival of captive-bred animals, especially so with fish reintroductions. High mortality is most often due to weakened antipredator skills, which could be enhanced through direct experience with predators and social learning. As yet, the relative efficiency of these learning methods has not been tested, and the significance of the factors determining how efficiently antipredator responses are transmitted socially from experienced (demonstrator) to predator naive (observer) individuals is largely unknown. Using hatchery-bred stock of the endangered Saimaa Arctic charr (Salvelinus alpinus), we show for the first time that: (1) contrary to theoretical predictions, acquired predator recognition was only socially transmitted from predator-experienced to predator-naive fish in groups with a smaller proportion of experienced than naive individuals, and that (2) socially acquired avoidance of the predator odors was as strong as in those fish conditioned with a combination of odors and predator exposure. We conclude that using social transmission procedures in training fish for reintroduction programs may provide considerable ecological, economical and ethical advantages.Communicated by J. Krause 相似文献
587.
Dirk Semmann Hans-Jürgen Krambeck Manfred Milinski 《Behavioral ecology and sociobiology》2005,57(6):611-616
To find conditions under which humans cooperate within groups of unrelated individuals has been of major interest in the behavioral sciences. The experimental paradigm for studying potential cooperation in social dilemmas is the public goods game. Here humans regularly fail to sustain a public resource cooperatively. However, the need to maintain good reputation for other social interactions, such as indirect reciprocity, has been identified as an effective mechanism to sustain cooperation in public goods situations. As a side effect of building a good reputation through cooperative actions, an individual provides direct benefits to members of his/her own social group. These benefits could be an incentive to reward a good reputation of group members. Here we show experimentally that building a good reputation through cooperative behavior in a public goods situation is rewarded in future social interactions, not only within ones own social group but also, at a similar level, in other social groups: humans regard cooperative behavior of others as an honest signal irrespective of past direct personal benefits. Reputation gained within as well as outside ones own social group can be a driving force for selfish individuals to cooperate in public goods situations, and thereby sustain any public resource.Communicated by T. Czeschlik 相似文献
588.
Bumblebees (Bombus terrestris) are attracted to those particular inflorescences where other bees are already foraging, a process known as local enhancement.
Here, we use a quantitative analysis of learning in a foraging task to illustrate that this attraction can lead bees to learn
more quickly which flower species are rewarding if they forage in the company of experienced conspecifics. This effect can
also be elicited by model bees, rather than live demonstrators. We also show that local enhancement in bumblebees most likely
reflects a general attraction to conspecifics that is not limited to a foraging context. Based on the widespread occurrence
of both local enhancement and associative learning in the invertebrates, we suggest that social influences on learning in
this group may be more common than the current literature would suggest and that invertebrates may provide a useful model
for understanding how learning processes based on social information evolve. 相似文献
589.
The haploid state of males in eusocial Hymenoptera—the ants, bees, and wasps—has been proposed as a driving force in the evolution of social behavior under the assumption that haploidy results in higher susceptibility to pathogens. In this study, we present the first test of the assumptions of the “haploid male susceptibility hypothesis”. We challenged males and workers of the bumblebee Bombus terrestris with its parasite Crithidia bombi but found no differences in either initial susceptibility or the intensity of infection between haploid males and diploid females. We reviewed observational studies on parasitism in haplodiploid insects and found that in 15 out of 26 cases, haploid males had lower parasite prevalence. However, the majority of available data related to nontransmissible parasites and thus any general statements about haploid susceptibility remain unclear. Using a simulation model, we studied how diverse genetic mechanisms could affect the values for resistance; results suggest that only a phenomenon that renders workers effectively haploid, e.g., imprinting, could explain our experimental results. A more likely explanation is that, in eusocial Hymenoptera with predominantly female populations, parasites may simply become more adapted to the more common female hosts and, thus, male haploid susceptibility may be hidden due to parasite adaptation. Our results do not support the idea that the haploid susceptibility hypothesis explains the origin or maintenance of social systems in the eusocial Hymenoptera. 相似文献
590.
Bayes methods for combining disease and exposure data in assessing environmental justice 总被引:1,自引:0,他引:1
Waller LANCE A. Louis THOMAS A. Carlin BRADLEY P. 《Environmental and Ecological Statistics》1997,4(4):267-281
Environmental justice reflects the equitable distribution of the burden of environmental hazards across various sociodemographic groups. The issue is important in environmental regulation, siting of hazardous waste repositories and prioritizing remediation of existing sources of exposure. We propose a statistical framework for assessing environmental justice. The framework includes a quantitative assessment of environmental equity based on the cumulative distribution of exposure within population subgroups linked to disease incidence through a dose-response function. This approach avoids arbitrary binary classifications of individuals solely as 'exposed' or 'unexposed'. We present a Bayesian inferential approach, implemented using Markov chain Monte Carlo methods, that accounts for uncertainty in both exposure and response. We illustrate our method using data on leukaemia deaths and exposure to toxic chemical releases in Allegheny County, Pennsylvania. 相似文献