An extended Moran process that captures the struggle for fitness.

Highlights • New strategies are typically disadvantageous in stable populations. • Stochasticity can delay the extinction of a new strategy in a large, stable population. • Individuals that adopt the new strategy can change the environment of the population. • Changes in the environment can affect the stability of the population. • In this case, the new strategy might become advantageous. Abstract When a new type of individual appears in a stable population, the newcomer is typically not advantageous. Due to stochasticity, the new type can grow in numbers, but the newcomers can only become advantageous if they manage to change the environment in such a way that they increase their fitness. This dynamics is observed in several situations in which a relatively stable population is invaded by an alternative strategy, for instance the evolution of cooperation among bacteria, the invasion of cancer in a multicellular organism and the evolution of ideas that contradict social norms. These examples also show that, by generating different versions of itself, the new type increases the probability of winning the struggle for fitness. Our model captures the imposed cooperation whereby the first generation of newcomers dies while changing the environment such that the next generations become more advantageous. [ABSTRACT FROM AUTHOR]