Identify the statement that describes the imperfection of natural selection. Identify the statement that describes the imperfection of natural selection. Natural selection has not had sufficient time to create the optimal design in each case but will do so given enough time. Natural selection is generally limited to modifying structures that were present in previous generations and in previous species. In many cases, phenotype is not merely determined by genotype but by the environment as well. Though we may not consider the fit between the current skeletal arrangements and their functions excellent, we should not doubt that natural selection ultimately produces the best design.