1st post-JSMB workshop on mathematical biology in Hayama (September 12th, Monday).
Date
September 12th, 2016
Time
Venue
Speakers
14:50 - 15:40
Jonas Schluter (Memorial Sloan Kettering Cancer Center, NY)
title
TBA
abstract
Microbiome biology is clearly relevant for human health, but the field is dominated by ever-increasing sequencing data. We lack theoretical frameworks and experimental systems to investigate how microbiome communities work, and how they affect host development and well-being. We need to develop new eco-evolutionary frameworks, and identify causal relationships between the microbiota and host phenotypes. Particularly interesting here are the ecological processes underlying the assembly of a healthy microbiome in the gut. I will present results from community ecology inspired models, and simulations of microbial communities in a computational gut that demonstrate how host secretions such as mucus, and immune system compounds such as IgA may act to ensure a stable and diverse microbiome. I will discuss how host secretions may be crucial in ensuring that the ‘right’ community colonizes the gut at the right time.
15:50 - 16:40
Cinthia M. Tanaka (University of Sao Paulo & Kyushu University)
title
Mathematical models for human social evolution
abstract
One of the features that distinguish human beings from other living species is our culture. However, since behaviors do not fossilize, it is difficult to reconstruct the past to get insights of why we are who we are. Along with ethnographic and experimental data, mathematical models have been extensively used to address the question of how our behaviors were shaped by evolution. In this presentation, I will talk about the mathematical models for social evolution that I have been studying as part of my PhD at University of Sao Paulo (Brazil) and during my internship at Kyushu University. In the first part, I will talk about one particular mathematical framework to tackle the well-known problem of the evolution of altruism in humans. We considered the implications of war conflicts to the spread of altruism in a population structured in groups. We explored the impact of migration and probability of war and we found out that wars may have helped the altruists to spread, in the context of hunter-gatherer populations. In the second part, I will talk about the survival of a local dialect against a national language. Our main goal was to define what conditions would allow a local dialect to be preserved in a local population. We considered different preferences regarding language use, as well as a parameter to account for conformity pressure suffered by individuals inside groups. We observed that when the group size is two, conformity level does not affect the final size of speakers of the national language. By increasing the number of individuals per group, we saw that conformity can play a role in enhancing the tendency predicted by the preferences of individuals. This may indicate that the size of the community an individual interacts may influence the fate of a local dialect.
16:50 - 17:40
Nobuto Takeuchi (University of Tokyo)
title
The origin of genes through spontaneous symmetry breaking
abstract
The heredity of the modern cell is provided by a small number of non-catalytic template molecules---the gene. How did genes originate? Here, we demonstrate the possibility that gene-like molecules emerge in protocells through spontaneous symmetry breaking between the complementary strands of replicating molecules. The model assumes a population of protocells, each containing a population of replicating catalytic molecules. Protocells are selected towards maximizing the catalytic activity of internal molecules, whereas molecules tend to evolve towards minimizing it in order to maximize their relative fitness within a protocell. These conflicting evolutionary tendencies at different levels induce symmetry breaking, whereby one strand of replicating molecules maintains catalytic activity and increases its copy number, whereas the other strand completely loses catalytic activity and decreases its copy number---like genes. The resulting asymmetry increases the equilibrium fitness of protocells by decreasing mutation pressure and inducing population bottlenecks in intracellular molecules. Our results implicate conflicting multilevel evolution as a key cause of the evolution of genetic complexity.
2nd post-JSMB workshop on mathematical biology in Hayama (September 23th, Friday).
Date
September 23th, 2016
Time
Venue
Speakers
14:00 - 14:50
Mayuko Nakamaru (Tokyo Tech), in collaboration with Akira Yokoyama (Tokyo Tech)
title
The effect of exclusion and participation on the evolution of cooperation
abstract
The evolution of cooperation in a group is an evolutionary puzzle because defectors always get a higher benefit than cooperators. When individuals participate in a group, they carefully evaluate the group members' reputation and then decide whether to join it. In some groups, membership is open to all of those who are willing to participate in the groups. In other groups, a candidate is excluded from membership if members in the group regard his reputation as bad. By means of computer simulations, we make the evolutionary game model and investigate how participation in groups and exclusion influence the evolution of cooperation in groups when group members play the public goods game. When the group's membership is open to all candidates and candidates can decide whether to join a group, the cooperation cannot be sustainable. While, cooperation evolves when a candidate cannot be a member unless all members in the group admit them to membership. We conclude that, not participation in a group but exclusion, which works as costless punishment on defectors, is essential to sustain cooperation in the public goods game.
15:00 - 15:50
Florence Débarre (College de France, France)
title
Social evolution in structured populations
abstract
Population structure is one of the factors that can explain the evolution of social behaviors such as altruism and spite. Previous theoretical studies have however showed that whether these behaviors actually evolve depends on apparently artificial model features, such as details of the life-cycles (e.g., synchronous vs. asynchronous generations, birth-death vs. death-birth updating rules), and whether social interactions affect individual fecundity or survival. In addition, these results are often obtained using specific population structures, and limiting assumptions such as weak selection and rare mutation. In this talk, I plan present conditions for the evolution of social behavior that go beyond some of those limitations, and allow to recover previous results as special cases. In particular (time permitting), I will show that relaxing the assumption of rare mutations can qualitatively affect the conditions under which altruism can evolve.
16:00 - 16:50
Ross D. Booton (University of Sheffield)
title
Modelling the effects of stress and infection in honey bee colonies
abstract
The recent decline in honey bee populations could have significant implications for ecological systems, economics and food security. No single cause of honey bee collapse has yet to be identified, although pesticides, mites and other pathogens have all been shown to have a sublethal effect. I will present a model of a honey bee hive and introduce the effects of stress and the impacts this has on infection within the colony.