Evolution of simple multicellular life forms indicates a shift in the unit of selec- tion from individual cells to larger complexes. Here we outline a finite population model that help to explore how natural selection lead to higher levels of organization.
Many theoretical models of evolution assume that all competing individuals experience the same environment. Here, we consider the more realistic scenario of evolution a finite population in any heterogeneous environment. We introduce a novel mathematical formalism to approach any form of spatial fitness heterogeneity and calculate exact results for the fixation probability.