For asexual reproduction, where we are interested only in the total number of mutations but not where they occur in the genome, a simple integer is sufficient to represent an individual.
A population is then simply an array of integers. In the simplest model of island populations, the size of the population will never grow beyond k, the carrying capacity of the environment, so it is only necessary to create an array of size k.
Another simplifying assumption we make is that all individuals are perfectly healthy at the beginning of the simulation. Thus the array should be initialized to all 0s, meaning every individual has 0 mutations.