203,029 research outputs found
Eco-evolutionary dynamics of social dilemmas
Social dilemmas are an integral part of social interactions. Cooperative
actions, ranging from secreting extra-cellular products in microbial
populations to donating blood in humans, are costly to the actor and hence
create an incentive to shirk and avoid the costs. Nevertheless, cooperation is
ubiquitous in nature. Both costs and benefits often depend non-linearly on the
number and types of individuals involved -- as captured by idioms such as `too
many cooks spoil the broth' where additional contributions are discounted, or
`two heads are better than one' where cooperators synergistically enhance the
group benefit. Interaction group sizes may depend on the size of the population
and hence on ecological processes. This results in feedback mechanisms between
ecological and evolutionary processes, which jointly affect and determine the
evolutionary trajectory. Only recently combined eco-evolutionary processes
became experimentally tractable in microbial social dilemmas. Here we analyse
the evolutionary dynamics of non-linear social dilemmas in settings where the
population fluctuates in size and the environment changes over time. In
particular, cooperation is often supported and maintained at high densities
through ecological fluctuations. Moreover, we find that the combination of the
two processes routinely reveals highly complex dynamics, which suggests common
occurrence in nature.Comment: 26 pages, 11 figure
Coalition Formation Games for Distributed Cooperation Among Roadside Units in Vehicular Networks
Vehicle-to-roadside (V2R) communications enable vehicular networks to support
a wide range of applications for enhancing the efficiency of road
transportation. While existing work focused on non-cooperative techniques for
V2R communications between vehicles and roadside units (RSUs), this paper
investigates novel cooperative strategies among the RSUs in a vehicular
network. We propose a scheme whereby, through cooperation, the RSUs in a
vehicular network can coordinate the classes of data being transmitted through
V2R communications links to the vehicles. This scheme improves the diversity of
the information circulating in the network while exploiting the underlying
content-sharing vehicle-to-vehicle communication network. We model the problem
as a coalition formation game with transferable utility and we propose an
algorithm for forming coalitions among the RSUs. For coalition formation, each
RSU can take an individual decision to join or leave a coalition, depending on
its utility which accounts for the generated revenues and the costs for
coalition coordination. We show that the RSUs can self-organize into a
Nash-stable partition and adapt this partition to environmental changes.
Simulation results show that, depending on different scenarios, coalition
formation presents a performance improvement, in terms of the average payoff
per RSU, ranging between 20.5% and 33.2%, relative to the non-cooperative case.Comment: accepted and to appear in IEEE Journal on Selected Areas in
Communications (JSAC), Special issue on Vehicular Communications and Network
Extending an eco-evolutionary understanding of biofilm-formation at the air-liquid interface to community biofilms
Growing bacterial populations diversify to produce a number of competing lineages. In the Pseudomonas fluorescens SBW25 model system, Wrinkly Spreader mutant lineages, capable of colonising the air-liquid interface of static microcosms by biofilm-formation, rapidly appear in diversifying populations with a fitness advantage over the ancestral wild-type strain. Similarly, a biofilm is rapidly produced by a community containing many biofilm-competent members, and selection by serial transfer of biofilm samples across microcosms results in a gradually changing community structure. Both the adaptive radiation producing Wrinkly Spreaders and the succession of biofilm communities in these static microcosms can be understood through evolutionary ecology in which ecological interactions and evolutionary processes are combined. Such eco-evolutionary dynamics are especially important for bacteria, as rapid growth, high population densities and strong selection in the context of infections can lead to fast changes in disease progression and resistance phenotypes, while similar changes in community function may also affect many microbially-mediated biotechnological and industrial processes. Evolutionary ecology provides an understanding of why bacterial biofilms are so prevalent and why they are such a successful colonisation strategy, and it can be directly linked to molecular analyses to understand the importance of pathways and responses involved in biofilm-formation
Social Norms and the Evolution of Conditional Cooperation
This paper develops a model of social norms and cooperation in large societies. Within this framework we use an indirect evolutionary approach to study the endogenous formation of preferences and the coevolution of norm compliance. Thereby we link the multiplicity of equilibria, which emerges in the presence of social norms, to the evolutionary analysis: Individuals face situations where many others cooperate as well as situations where a majority free-rides. The evolutionary adaptation to such heterogenous environments will favor conditional cooperators, who condition their pro-social behavior on the others' cooperation. As conditional cooperators react flexibly to their social environment, they dominate free-riders as well as unconditional cooperators
- …