Transitions between homophilic and heterophilic modes of cooperation

Cooperation is ubiquitous in biological and social systems. Previous studies revealed that a preference toward similar appearance promotes cooperation, a phenomenon called tag-mediated cooperation or communitarian cooperation. This effect is enhanced when a spatial structure is incorporated, because space allows agents sharing an identical tag to regroup to form locally cooperative clusters. In spatially distributed settings, one can also consider migration of organisms, which has a potential to further promote evolution of cooperation by facilitating spatial clustering. However, it has not yet been considered in spatial tag-mediated cooperation models. Here we show, using computer simulations of a spatial model of evolutionary games with organismal migration, that tag-based segregation and homophilic cooperation arise for a wide range of parameters. In the meantime, our results also show another evolutionarily stable outcome, where a high level of heterophilic cooperation is maintained in spatially well-mixed patterns. We found that these two different forms of tag-mediated cooperation appear alternately as the parameter for temptation to defect is increased.Comment: 16 pages, 7 figure

The effects of tags on the evolution of honest signaling

In the study described here we examine the importance of social tags in the emergence and maintenance of signaling, using the Sir Philip Sydney Game. We use tags in the calcu-lation of inclusive fitness for members in a finite population, and analyze their evolution under different population distri-butions. We support the claim that inclusive fitness theory may not be sufficient to explain the evolution of cooperation. While cooperativity through honest signaling is sometimes achieved with tag-based relatedness, we suggest that the im-portance of tag-based mechanisms may not simply be due to their role in kin selection

The evolution of altruism and the serial rediscovery of the role of relatedness.

The genetic evolution of altruism (i.e., a behavior resulting in a net reduction of the survival and/or reproduction of an actor to benefit a recipient) once perplexed biologists because it seemed paradoxical in a Darwinian world. More than half a century ago, W. D. Hamilton explained that when interacting individuals are genetically related, alleles for altruism can be favored by selection because they are carried by individuals more likely to interact with other individuals carrying the alleles for altruism than random individuals in the population ("kin selection"). In recent decades, a substantial number of supposedly alternative pathways to altruism have been published, leading to controversies surrounding explanations for the evolution of altruism. Here, we systematically review the 200 most impactful papers published on the evolution of altruism and identify 43 evolutionary models in which altruism evolves and where the authors attribute the evolution of altruism to a pathway other than kin selection and/or deny the role of relatedness. An analysis of these models reveals that in every case the life cycle assumptions entail local reproduction and local interactions, thereby leading to interacting individuals being genetically related. Thus, contrary to the authors' claims, Hamilton's relatedness drives the evolution to altruism in their models. The fact that several decades of investigating the evolution to altruism have resulted in the systematic and unwitting rediscovery of the same mechanism is testament to the fundamental importance of positive relatedness between actor and recipient for explaining the evolution of altruism

The maintenance and spread of cooperation in social networks in natural populations

Social interaction is crucial for social animals to thrive, but it comes with both benefits and costs. The social network approach helps to identify how social processes like cooperation are influenced by individual and population-level characteristics. Factors like individual recognition, familiarity, and social stability play a role in promoting tolerance and cooperation; and understanding these factors can provide insights into how social networks, cooperation, and other social behaviors evolve in different species. In this thesis, I examine how social processes interact with spatial and temporal factors to influence fitness and other outcomes in wild birds (Paridae). I begin by establishing a theoretical foundation for my work by reviewing the concepts of cooperation and individual recognition and how they can be better understood through a social network approach (Chapters 2 & 3). Using experimental data, I explore the processes that may impact cooperative behavior by examining leading behavior during mixed-species foraging (Chapter 4) and demonstrate that motivation and dominance, as well as spatio- temporal effects, are determinants of this behavior. Drawing on these insights, I then use long-term breeding data to show that familiarity among neighbors as well as familiarity within breeding pairs influences fitness (Chapter 5). I also demonstrate that different kinds of social relationships have different effects on reproductive outcomes (Chapter 6). All in all, I demonstrate that social connections have implications for fitness, and highlight the importance of accounting for spatial, temporal, and cognitive components when studying the ecology and evolution of sociality

The Impact of High School Extracurriculars: Similarities and Differences in Sense of Community Among Competitive, Performance, and Participatory Activities

Extant research links high sense of community in adolescence to adaptive outcomes such as enhanced motivation, self-efficacy, and coping ability (Battistich, Solomon, Watson, & Schaps, 1997; Vieno, Perkins, Smith, & Santinello, 2005; Henry & Slater, 2007), as well as reduced stress, anxiety, and depression (Chipuer, Bramston, & Pretty, 2002). In light of these findings, the present study was designed to assess the relationship between high school students’ participation in extracurricular activities and their perceptions of sense of community, enjoyment, and commitment, as well as the aspects of these organizations that help to facilitate feelings of community. Study 1 participants (N= 701) were 276 males and 425 females (Mage= 16.51) actively engaged in competitive (e.g., sports; n= 218), performance (e.g., music; n= 370), and participatory (e.g., clubs; n= 113) activities in high school. Students responded to survey items assessing perceived sense of community, as well as enjoyment and commitment. Study 2 participants (N= 20) were three males and 17 females who participated in Study 1. MANOVAs and follow-up tests revealed significantly lower perceptions of sense of community, enjoyment, and commitment among students in performance groups than competitive and participatory groups. Comments from participants in Study 2 suggest that students in performance groups may experience lower enjoyment, commitment, and sense of community due to the compulsory nature of performance activities in high school. These findings suggest that there is a tension between the needs of the individual and the group, and that psychological sense of community may act as a buffer to reduce this tension. This study proposes that the purposeful facilitation of psychological sense of community by group leaders could potentially be utilized to help improve group outcomes. For anthropologists engaging in applied work, working to facilitate psychological sense of community among the populations they work with could also have a positive impact on program outcomes. In a broader application than the study population, grassroots communities may find that purposefully facilitating psychological sense of community within their programs will help them achieve their goals. Additionally, the present study presents one potential model for the purposeful facilitation of sense of community

Tag-based modules in genetic programming

In this paper we present a new technique for evolving mod-ular programs with genetic programming. The technique is based on the use of “tags ” that evolving programs may use to label and later to refer to code fragments. Tags may refer inexactly, permitting the labeling and use of code fragments to co-evolve in an incremental way. The technique can be implemented as a minor modification to an existing, general purpose genetic programming system, and it does not re-quire pre-specification of the module architecture of evolved programs. We demonstrate that tag-based modules readily evolve and that this allows problem solving effort to scale well with problem size. We also show that the tag-based module technique is effective even in complex, non-uniform problem environments for which previous techniques per-form poorly. We demonstrate the technique in the context of the stack-based genetic programming system PushGP, but we also briefly discuss ways in which it may be used with other kinds of genetic programming systems

Intraspecific variation in reproductive ecology and success of a keystone stream fish, bluehead chub

2019 Fall.Includes bibliographical references.To view the abstract, please see the full text of the document