Following the work of Stephens and coworkers on the coarse-grained dynamics of genetic systems, we work towards a possible generalisation in the context of genetic algorithms, giving as examples schemata, genotype-phenotype mappings, and error classes in the Eigen model. We discuss how the dynamics transforms under a coarse-graining, comparing and contrasting different notions of invariance. We work out some examples in the two-bit case, to illustrate the ideas and issues. We then find a bound for the Selection Weighted Linkage Disequilibrium Coefficient for the two-bit onemax problem.