Evolution of cooperation in multilayer networks

Dissertation presented as the partial requirement for obtaining a Master's degree in Information Management, specialization in Information Systems and Technologies ManagementIndividuals take part in multiple layers of networks of interactions simultaneously. These interdependent networks account for the different sort of social ties individuals maintain per layer. In each layer individuals participate in N-Player Public Goods Games where benefits collected increase with amounts invested. It is, however, tempting to be a free-rider, i.e., to take advantage of the common pool without contributing to it, a situation from which a social dilemma results. This thesis offers new insights on how cooperation dynamics is shaped by multiple layers of social interactions and diversity of contributions invested per game. To this end, we resort to Evolutionary Game Theory and Network Science to provide a convenient framework to address the most important prototypical social conflicts and/or dilemmas in large networked populations. In particular, we propose a novel mean-field approach capable of tracking the self-organization of Cooperators when co-evolving with Defectors in a multilayer environment. We show that the emerging collective dynamics, which depends (i) on the underlying layer networks of interactions and (ii) on the criteria to share a finite investment across all games, often does not bear any resemblance with the local processes supporting them. Our findings suggest that, whenever individual investments are distributed among games or layers, resilience of cooperation against free-riders increases with the number of layers, and that cooperation emerges from a non-trivial organization of cooperation across the layers. In opposition, under constant, non-distributed investments, the level of cooperation shows little sensibility to variations in the number of layers. These findings put in evidence the importance of asymmetric contributions across games and social contexts in the emergence of human cooperation

Using MapReduce Streaming for Distributed Life Simulation on the Cloud

Distributed software simulations are indispensable in the study of large-scale life models but often require the use of technically complex lower-level distributed computing frameworks, such as MPI. We propose to overcome the complexity challenge by applying the emerging MapReduce (MR) model to distributed life simulations and by running such simulations on the cloud. Technically, we design optimized MR streaming algorithms for discrete and continuous versions of Conway’s life according to a general MR streaming pattern. We chose life because it is simple enough as a testbed for MR’s applicability to a-life simulations and general enough to make our results applicable to various lattice-based a-life models. We implement and empirically evaluate our algorithms’ performance on Amazon’s Elastic MR cloud. Our experiments demonstrate that a single MR optimization technique called strip partitioning can reduce the execution time of continuous life simulations by 64%. To the best of our knowledge, we are the first to propose and evaluate MR streaming algorithms for lattice-based simulations. Our algorithms can serve as prototypes in the development of novel MR simulation algorithms for large-scale lattice-based a-life models.https://digitalcommons.chapman.edu/scs_books/1014/thumbnail.jp

The role of visual adaptation in cichlid fish speciation

D. Shane Wright (1) , Ole Seehausen (2), Ton G.G. Groothuis (1), Martine E. Maan (1) (1) University of Groningen; GELIFES; EGDB(2) Department of Fish Ecology & Evolution, EAWAG Centre for Ecology, Evolution and Biogeochemistry, Kastanienbaum AND Institute of Ecology and Evolution, Aquatic Ecology, University of Bern.In less than 15,000 years, Lake Victoria cichlid fishes have radiated into as many as 500 different species. Ecological and sexual sel ection are thought to contribute to this ongoing speciation process, but genetic differentiation remains low. However, recent work in visual pigment genes, opsins, has shown more diversity. Unlike neighboring Lakes Malawi and Tanganyika, Lake Victoria is highly turbid, resulting in a long wavelength shift in the light spectrum with increasing depth, providing an environmental gradient for exploring divergent coevolution in sensory systems and colour signals via sensory drive. Pundamilia pundamila and Pundamilia nyererei are two sympatric species found at rocky islands across southern portions of Lake Victoria, differing in male colouration and the depth they reside. Previous work has shown species differentiation in colour discrimination, corresponding to divergent female preferences for conspecific male colouration. A mechanistic link between colour vision and preference would provide a rapid route to reproductive isolation between divergently adapting populations. This link is tested by experimental manip ulation of colour vision - raising both species and their hybrids under light conditions mimicking shallow and deep habitats. We quantify the expression of retinal opsins and test behaviours important for speciation: mate choice, habitat preference, and fo raging performance