Next NAME/Alergic: Hywel Williams, Wed 7th May, ARUN401

There will be a joint Alergic/NAME (New Approaches to Modeling Evolution & Ecology) on Wed 7th May, 16:30, ARUN401 when Hywel Williams from the Earth System Modeling Group, University of East Anglia will be presenting:

Environmental regulation in a network of simulated microbial ecosystems

The Earth possesses a number of regulatory feedback mechanisms involving life. In the absence of a population of competing biospheres it has proved hard to find a robust evolutionary mechanism that would generate environmental regulation. It has been suggested that regulation must require altruistic environmental alterations by organisms and would therefore be evolutionarily unstable. This need not be the case if organisms alter the environment as a selectively neutral by-product of their metabolism, as in the majority of biogeochemical reactions, but the question then arises: why should the combined by-product effects of the biota have a stabilising, rather than destabilising, influence on the environment? In certain conditions selection acting above the level of the individual can be an effective adaptive force. Here we present an evolutionary simulation model in which environmental regulation involving higher level selection robustly emerges in a network of interconnected microbial ecosystems. Spatial structure creates conditions for a limited form of higher level selection to act on the collective environment-altering properties of local communities. Local communities that improve their environmental conditions achieve larger populations and are better colonisers of available space, while local communities that degrade their environment shrink and become susceptible to invasion. The spread of environment-improving communities alters the global environment towards the optimal conditions for growth and tends to regulate against external perturbations. This work suggests a new mechanism for environmental regulation that is consistent with evolutionary theory.

All welcome!

Chris Watkins talk now available online

The joint NAME/Alergic talk given my Chris Watkins is now available on Google Video:

http://video.google.co.uk/videoplay?docid=-3703850700473118837&hl=en-GB

Next NAME/Alergic: Chris Watkins, Wed 24th Oct, ARUN401

The next NAME meeting is a combined NAME/Alergic event. Chris Watkins, Royal Holloway, will be talking about his research into information theoretic approaches to evolution and in particular the 'channel capacity' of evolution. Please see abstract below.

16:30, Wednesday 24th October
Arundel room 401

All welcome.



Abstract

This talk will consider some familiar genetic and evolutionary algorithms from a new point of view. Instead of viewing these algorithms as optimisation methods, I will consider them information-theoretically, as communication channels. After a brief introduction to Shannon's theory of communication, I will show how to view an evolutionary algorithm as a communication channel, and then show that different algorithms have very different channel capacities.
Intuitively, the channel capacity of an evolutionary algorithm is a measure of how much information -- or how much complexity -- can be put into the "genomes" as a result of selection. This seems a basic limitative computational property, which may be relevant to choosing useful regimes to get evolutionary algorithms to work effectively.
In biological evolution, in each generation genetic information is degraded by mutation, but also in some sense restored by selection. Some natural basic questions are: How much information could be encoded in a genome as a result of selection? How complex could organisms conceivably become? Does the potential complexity depend on whether the organisms are sexual? How could information be encoded most efficiently, in the sense that the greatest amount could be encoded for the lowest intensity of selection? The theoretical approach I will present may have some bearing on these questions.



New Approaches to Modelling Evolution/Ecosystems

http://newapproaches.blogspot.com

Next meeting: Wed 17th October, 14:00, room TBC

A PDF of David's talk can be found online here.

Professor David Waxmam from the Department of Biology and Environmental Science, University of Sussex will be leading the next NAME meeting this Wednesday 14:00, room TBC. The topic for this meeting is random genetic drift in populations.

NAME meetings are biased towards group discussions rather than a single presentation with questions. Therefore they are interactive and we positively welcome contributions from all participants. Come armed with puzzles, comments and queries!

All welcome.

Alergic meeting Wed 10 October, 16:30, ARUN 401

The first meeting of the term for Alergic (Artificial Life Reading Group in Cogs) is today. The NAME group can be seen as a spin off from Alergic and used the 'Alergic slot' on Wednesday afternoons. In today's meeting we will introduce the NAME group and discuss where and when to hold NAME meetings this term.

Next meeting: Wed 22nd August, 16:00, room TBC

James Dyke will be presenting at the next NAME meeting, this coming Wednesday 22nd August at 16:00, room TBC. The talk will be approximately 30 minutes long in order to allow discussion afterwards. Those interested in niche construction and ecosystems engineering as well as ecosystems complexity/stability may find the presentation and discussion of use.

Title:
Increasing complexity can increase stability in a self-regulating ecosystem

Abstract:
A long standing debate within ecology is to what extent ecosystem complexity and stability are related. Landmark theoretical studies claimed that the more complex an ecosystem, the more unstable it is likely to be. Stability in an ecosystems context can be assessed in different ways. In this paper we measure stability in terms of a model ecosystem's ability to regulate environmental conditions. We show how increasing biodiversity in this model can result in the regulation of the environment over a wider range of external perturbations. This is achieved via changes to the ecosystem's resistance and resilience. This result crucially depends on the feedback that the organisms have on their environment.

Next meeting: Wed 1st August, 16:30, ARUN401

The next NAME meeting will see Chris Gordon-Smith present his research into the origins of life with his SimSoup software.

Abstract:

Network dynamics may have played a key role in the Origin of Life. ‘Smart’ molecules such as template replicators and enzymes may not have been necessary in the first evolving entities. This paper shows evolution of a metabolic network using the SimSoup artificial chemistry simulation. The context and conceptual background for SimSoup is first outlined. The model is then described, and differences with other models are highlighted. SimSoup has network elements that correspond directly to the unimolecular and bimolecular elementary reaction schemes of physical chemistry. These network elements can be combined in very general ways to produce ‘compound interactions’ which can be catalytic.The model includes mass conservation, reaction rates based on considerations of energy and thermodynamics, and cycle detection. A run of the model is presented showing an evolutionary process with selection for high entropy production. The network includes a large number of cyclic flows. It evolves through a series of persistent states, each of which can be regarded as a different ‘species’.