take over these immediate neighbourhoods and then interact with adjacent neighbourhoods. This model is useful in showing how pockets of co-operators can invade and introduce altruism in the Prisoners Dilemma game, where Tit for Tat (TFT) is a Nash Equilibrium but NOT also an ESS. Spatial structure is sometimes abstracted into a general network of interactions. This is the foundation of evolutionary graph theory. Effects of having information In evolutionary game theory as in conventional Game Theory the effect of Signalling (the acquisition of information) is of critical importance, as in Indirect Reciprocity in Prisoners Dilemma (where contests between the SAME paired individuals are NOT repetitive). This models the reality of most normal social interactions which are non-kin related. Unless a probability measure of reputation is available in Prisoners Dilemma only direct reciprocity can be achieved. With this information indirect reciprocity is also supported. Alternatively, agents might have access to an arbitrary signal initially uncorrelated to strategy but becomes correlated due to evolutionary dynamics. This is the green-beard effect (see side-blotched lizards, above) or evolution of ethnocentrism in humans. Depending on the game, it can allow the evolution of either cooperation or irrational hostility. From molecular to multicellular level, a signaling game model with information asymmetry between sender and receiver might be appropriate, such as in mate attraction or evolution of translation machinery from RNA strings. Finite populations Many evolutionary games have been modelled in finite populations to see the effect this may have, for example in the success of mixed strategies. See also Adaptive dynamics Behavioral ecology Dynamical systems Evolutionary dynamics Gene-centered view of evolution Memetics Notes References Further reading Davis, Morton,; "Game Theory – A Nontechnical Introduction", Dover Books, Dawkins, Richard; "The Selfish Gene", Oxford University Press, Dugatkin and Reeve; "Game Theory and Animal Behavior", Oxford University Press, Hofbauer and Sigmund; "Evolutionary Games and Population Dynamics", Cambridge University Press, Kohn, Marek; "A Reason for Everything", Faber and Faber, Sandholm, William H.; "Population Games and Evolutionary Dynamics", The MIT Press, Segerstrale, Ullica; "Nature's Oracle - The life and work of W.D. Hamilton", Oxford University Press, 2013, Sigmund, Karl; "Games of Life", Penguin Books, also Oxford University Press, 1993, Vincent and Brown; "Evolutionary Game Theory, Natural Selection and Darwinian Dynamics", Cambridge University Press, External links Evolutionary game theory at the Stanford Encyclopedia of Philosophy Evolving Artificial Moral Ecologies at The Centre for Applied Ethics, University of British Columbia 4Strategies Of