Mendel’s Accountant (hereafter referred to as “Mendel”) is a state-of-the-art forward-time population genetics model that tracks millions of individual mutations with their unique effects on fitness and unique location within the genome through large numbers of generations. It treats the process of natural selection in a precise way. It allows a user to choose values for a large number of parameters such as those specifying the mutation effect distribution, reproduction rate, population size, and variations in environmental conditions. Mendel is thus a versatile and capable research tool that can be applied to problems in human genetics, plant and animal breeding, and management of endangered species. With its user-friendly graphical user interface and its ability to run on laptop computers it can also be fruitfully employed in teaching genetics and genetic principles, even at a high school level. Mendel is freely available to users and can be downloaded from the web.
When biologically realistic parameters are selected, Mendel shows consistently that genetic deterioration is an inevitable outcome of the processes of mutation and natural selection. The primary reason is that most deleterious mutations are too subtle to be detected and eliminated by natural selection and therefore accumulate steadily generation after generation and inexorably degrade fitness
