Detailed programme - MiLS meeting 21/03/16

10:30 Arrival and coffee

11:00 Dr. Anne Kandler (City University London)

Title: An inference framework for analysing temporal patterns of frequency change in sparse population data

Abstract: Evolutionary processes often manifest themselves in temporal frequency changes of biological or cultural traits. Those temporal changes are usually observable and researchers in a variety of scientific disciplines are confronted with the problem of identifying the evolutionary processes that could have caused the observed frequency changes. This inverse problem gains particular importance in historic cultural studies where frequencies data (e.g. gained from the archaeological record) are the only available empirical evidence of past cultural traditions. But despite its importance it is far from clear whether the inverse problem is infact well-posed and in this talk we ask the question of how much information about underlying evolutionary processes can be inferred from sparse population level data. To do so we develop a generative inference framework consisting of two steps. Firstly, we generate theoretical patterns of temporal frequency change conditioned on a specific evolutionary process and secondly, we use statistical comparisons (in form of approximate Bayesian computation) to establish which evolutionary processes could have produced the observed frequency data. In this way we infer underlying processes directly from the available data without any equilibrium assumption. This framework naturally allows us to explore the theoretical limits of inferring processes from (sparse) population-level frequency data. We apply our model to a dataset describing pottery from settlements of some of the first farmers in Europe (the LBK culture) and conclude that the observed frequency dynamic of different types of decorated pottery is consistent with pro-novelty selection, a preference for ‘young’ pottery types which is potentially indicative of fashion trends.

12:00 Dr. Spencer Thomas (University of Surrey)

Title: Systematic analysis of altruism"

Abstract: Altruism, and mutualistic behaviours, can be observed in a large number of social and biological systems. Although cooperation at a cost to the individual is a well known phenomenon, its origins and properties are poorly understood. The evolution of such behavioural traits are thought to be based on environmental conditions, and some conceptual arguments have been made based on observations of systems such as insect colonies. However, there has been little effort to systematically investigate models of altruism. As a consequence, questions regarding altruistic dependencies and possible transitions to other states remain open. In this work a systematic study of altruism addresses these questions and uncovers the effect of environmental condition on systems dynamics. Several bifurcations are observed in the system, including the emergence of bi-stable states and limit points. These results may help us understand why some systems develop altruistic traits over others, and what conditions would be required for a transition to another strategy.

12:30 Lunch

13:30 Prof. Stuart Townley (University of Exeter)

Title: Evolutionary dynamics: a control systems perspective

14:30 Dr. Jens Starke (Queen Mary University of London)

Title: Equation-free analysis of collective behaviour in pedestrian models

Abstract: Pedestrian modelling is often done by microscopic agent-based models. These models form on one side complex systems with many degrees of freedom which makes analysis with standard methods difficult but contain on the other side not enough particle-type pedestrians to perform a limit to a continuoum discription. It will be shown that the collective behaviour of these type of models can be analyzed by so-called equation-free methods. These allow to perform numerical investigations of the collective behaviour for which no explicit equations are available. This includes continuation and bifurcation analysis of the collective behaviour depending on model parameters.

15:00 Dr. Tom Ezard (University of Southampton)

Title: Are there limits to the number of species that can co-exist on Earth?

Abstract: Interactions among individuals regulate biodiversity. Co-dependent geological, biological and climatic changes obscure those biotic interactions in deep time, making it hard to discern dominant modes from their interplay. Here, using the exceptional fossil record of Cenozoic Era macroperforate lanktonic foraminifera, we assess the evidence for alternative modes of macroevolutionary competition. Models of fixed biotic competition were overwhelmingly rejected. Our models support environmentally dependent finite upper bounds on species richness and a macroevolutionary form of contest competition that yields a logistic upper limit. In the best-supported model, temperature affects the per-lineage diversification rate, while temperature and the number of sediment packages affects the upper limit. The support for contest competition implies that incumbency constrains species richness by restricting niche availability, but that the number of macroevolutionary niches varies as a function of environmental changes.

15:30 Tea

16:00 Jim Allen (University of Surrey)

Title: Cooperation on multilayered networks

16:30 Dr. Ben Adams (University of Bath)

Title: Demographic structures, human behaviour and the management of ebola, dengue and cholera epidemics.

Abstract: The transmission of infectious diseases is fundamentally entwined with demography and behaviour. In this talk I will introduce three mathematical models that offer basic insights into how demographic and behavioural factors affect epidemic risk and the effectiveness of control strategies for three quite different infectious diseases: ebola, where transmission occurs via close contact between people, dengue/zika where transmission occurs via mosquitoes, and cholera where transmission occurs via the environment.

17:00 Klodeta Kura (City University London)

Title: A game-theoretical winner and loser model of dominance hierarchy formation

Abstract: Animals that live in groups commonly form themselves into dominance hierarchies which are used to allocate important resources such as access to mating opportunities and food. We develop a model of dominance hierarchy formation based upon the concept of winner and loser effects, where we analyse the temporal dynamic and the average behaviour of hierarchies emerging from different combinations of these effects. We investigate if we can achieve hierarchy linearity and if so, when it is established. We then develop a game-theoretical version of this model, where individuals choose a strategic level of aggressiveness. For different combinations of reward and cost we find the (unique) evolutionarily stable strategy (ESS) and its associated expected payoff by using two different payoff functions. We analyse how the ESS changes when we vary the reward and cost, and the effect of different payoff functions, using both analysis and simulations to get our results.

17:30 Close