How threats influence the evolutionary resolution of within-group conflict.

© University of Chicago Press. This is the final published version of the article, deposited in accordance with SHERPA RoMEO guidelines. Also available from: http://www.jstor.org/stable/10.1086/598489Most examples of cooperation in nature share a common feature: individuals can interact to produce a productivity benefit or fitness surplus, but there is conflict over how these gains are shared. A central question is how threats to exercise outside options influence the resolution of conflict within such cooperative associations. Here we show how a simple principle from economic bargaining theory, the outside option principle, can help to solve this problem in biological systems. According to this principle, outside options will affect the resolution of conflict only when the payoff of taking up these options exceeds the payoffs individuals can obtain from bargaining or negotiating within the group; otherwise, threats to exercise outside options are not credible and are therefore irrelevant. We show that previous attempts to incorporate outside options in synthetic models of reproductive conflict fail to distinguish between credible and incredible threats, and then we use the outside option principle to develop credible synthetic models in two contexts: reproductive skew and biparental care. A striking prediction of our analysis is that outside options are least relevant to the resolution of conflict in cooperative groups of kin and are most relevant in transient associations or interactions among nonrelatives. Our analysis shows a way to link the resolution of within-group conflict to the environmental setting in which it occurs, and it illuminates the role of threats in the evolution of social behavior

Evidence for frequent incest in a cooperatively breeding mammal

Journal ArticleResearch Support, Non-U.S. Gov'tCopyright © 2014 The Authors.As breeding between relatives often results in inbreeding depression, inbreeding avoidance is widespread in the animal kingdom. However, inbreeding avoidance may entail fitness costs. For example, dispersal away from relatives may reduce survival. How these conflicting selection pressures are resolved is challenging to investigate, but theoretical models predict that inbreeding should occur frequently in some systems. Despite this, few studies have found evidence of regular incest in mammals, even in social species where relatives are spatio-temporally clustered and opportunities for inbreeding frequently arise. We used genetic parentage assignments together with relatedness data to quantify inbreeding rates in a wild population of banded mongooses, a cooperatively breeding carnivore. We show that females regularly conceive to close relatives, including fathers and brothers. We suggest that the costs of inbreeding avoidance may sometimes outweigh the benefits, even in cooperatively breeding species where strong within-group incest avoidance is considered to be the norm.NERCDeutsche Forschungsgemeinschaft standard gran

Using social parasitism to test reproductive skew models in a primitively eusocial wasp

Remarkable variation exists in the distribution of reproduction (skew) among members of cooperatively breeding groups, both within and between species. Reproductive skew theory has provided an important framework for understanding this variation. In the primitively eusocial Hymenoptera, two models have been routinely tested: concessions models, which assume complete control of reproduction by a dominant individual, and tug-of-war models, which assume on-going competition among group members over reproduction. Current data provide little support for either model, but uncertainty about the ability of individuals to detect genetic relatedness and difficulties in identifying traits conferring competitive ability mean that the relative importance of concessions versus tug-of-war remains unresolved. Here, we suggest that the use of social parasitism to generate meaningful variation in key social variables represents a valuable opportunity to explore the mechanisms underpinning reproductive skew within the social Hymenoptera. We present a direct test of concessions and tug-of-war models in the paper wasp Polistes dominulus by exploiting pronounced changes in relatedness and power structures that occur following replacement of the dominant by a congeneric social parasite. Comparisons of skew in parasitized and unparasitized colonies are consistent with a tug-of-war over reproduction within P. dominulus groups, but provide no evidence for reproductive concessions

Adjustment of costly extra-group paternity according to inbreeding risk in a cooperative mammal

Females of many animal species seek mating opportunities with multiple males, despite being able to obtain sufficient sperm to father their offspring from a single male. In animals that live in stable social groups, females often choose to mate outside their group resulting in extra-group paternity. One reason proposed to explain female choice for extra-group males is to obtain compatible genes, for example in order to avoid inbreeding depression in offspring. The benefits of such extra-group paternities could be substantial if they result in fitter, outbred offspring. However, avoiding inbreeding in this way could be costly for females, for example through retaliation by cuckolded males or through receiving aggression whilst prospecting for extra-group mating opportunities. We investigate the costs and benefits of extra-group paternity in the banded mongoose Mungos mungo, a cooperatively breeding mammal in which within-group mates are sometimes close relatives. We find that pups born to females that mate with extra-group males are more genetically heterozygous, are heavier and are more likely to survive to independence than pups born to females that mate within their group. However, extra-group matings also involve substantial costs as they occur during violent encounters that sometimes result in injury and death. This appears to lead female banded mongooses to adaptively adjust extra-group paternity levels according to the current risk of inbreeding associated with mating within the group. For group-living animals, the costs of inter-group interactions may help to explain variation in both inbreeding rates and extra-group paternity within and between species

Location and group size influence decisions in simulated intergroup encounters in banded mongooses

In social species that cooperatively defend territories the decision to retreat or attack in contests between groups is likely to depend on ecological and social factors. Previous studies have emphasized the importance of the encounter location or the size of competing groups on the outcome. In addition, the identity of the intruder, whether familiar or stranger, may also play a role. To test whether the same factors affect the resident group's decisions already at the beginning of contests, we simulated intergroup encounters in banded mongooses (Mungos mungo). When spotting rival groups banded mongooses emit "screeching calls” which lead group members to bunch up. With playbacks of these calls, we tested how the groups' response was affected by the following factors: 1) the location of the playback in relation to their territory (exclusive use vs. overlap); 2) the number of resident individuals; and 3) the origin of calls (neighbor vs. stranger) used. Subjects were more likely to approach the loudspeakers and arrive within 1 m of the speakers in the exclusive use zone than in the overlap zone. Moreover, larger groups tended to be more likely to move toward the loudspeakers and were also more likely to arrive there. The origin of calls used in the playbacks did not affect the groups' responses. These findings exemplify the importance of the combined effect of location and group size on group decisions during impending intergroup contes

The role of threats in animal cooperation

In human societies, social behaviour is strongly influenced by threats of punishment, even though the threats themselves rarely need to be exercised. Recent experimental evidence suggests that similar hidden threats can promote cooperation and limit within-group selfishness in some animal systems. In other animals, however, threats appear to be ineffective. Here I review theoretical and empirical studies that help to understand the evolutionary causes of these contrasting patterns, and identify three factors—impact, accuracy and perception—that together determine the effectiveness of threats to induce cooperation

10. D40TA使用経験(第513回千葉医学会 第5回麻酔科例会 第10回千葉麻酔懇談会)

<p>Parameter sensitivity analysis for parameters related to postprandial insulin dynamics; (A,C,E) Predicted plasma glucose concentrations (mM) (B,D,F). Predicted plasma insulin concentrations (ng/ml).</p

Evolution of menopause.

Johnstone and Cant introduce menopause and the phenomenon of an extended post-reproductive life found in humans and very few other mammals

Internet-Based ICT Usage By South African SMEs: The Barriers Faced By SMEs

Previous research estimates that 8 out of 10 small and medium enterprises (SMEs) do not operate for more three years (Mason 2015). According to OECD ([sa]), the major problems encountered by SMEs relate to financing and regulatory burdens. However, with information technology, SMEs are able to narrow the information gap, which leads to improved strategies and decision making (OECD [sa]). In today’s competitive world, information communication technology (ICT) is recognized as a crucial success factor for SMEs. ICT refers to the accessing and communication of information using various technologies such as the internet, wireless networks and cellphones (TechTerms 2010). This research study investigates SMEs’ perception of the barriers in adopting ICT in the South African context. The objective of this paper is to determine ICT adoption and the perceived barriers associated with it among South African SMEs. A review of ICT within an SME context is examined. Through judgement sampling, a questionnaire was distributed to gather the responses of 90 SMEs. The most important barriers that were highlighted by the results of the study are the high cost of ICT systems as well as the lack of knowledge to maintain and use ICT. The challenge is to ensure that South African SMEs continue to increase the adoption of ICT. It is envisaged that by determining the barriers they face and providing recommendations as to how they can overcome these barriers, this research will assist SMEs to become more successful, as they play a vital role in the South African economy

Establishing The Challenges Affecting South African SMEs

Cant andLigthelm (2003) estimate that 70-80 percent of SMEs fail.  A number of elements and challenges have beenidentified as contributing factors to the high failure rate of SMEs in SouthAfrica.  The research investigates theextent to which the identified variables affect South African SMEs.  The objective of this paper is to determine towhat extent SMEs experience selected challenges or issues that negativelyinfluence the success of the business.  Challengesand issues include exogenous macro environmental variables and endogenousenvironmental variables, namely marketing.  A questionnaire was constructed and judgementsampling was used to gather the responses of 81 SMEs.  The research identified inflation and interestrates, crime and unemployment, low demand for products, the wrong pricing strategiesimplemented and the location of the business to be the major problemsexperienced by SMEs.  The challenge nowis to improve the skills and capabilities of SMEs to ensure their success asthey play a vital role in the South African economy