Final answer:
Genetic and nongenetic variables both have an impact on animal performance, which can be observed through the processes of artificial and natural selection. While genetics involves the hereditary factors that contribute to traits within populations, nongenetic factors encompass environmental and epigenetic influences.
Step-by-step explanation:
The similarity between genetic and nongenetic variables is that they both affect animal performance. This influence can be seen in the principles of artificial selection and natural selection. Genetic factors, such as gene flow, genetic drift, and mutation, play a crucial role in the evolution of species through natural selection. Nongenetic variables, including environmental factors, can also influence animal performance by affecting the expression of genes (epigenetics) and the population dynamics. Both genetic and nongenetic factors can be influenced or controlled by humans to some extent; for instance, humans employ artificial selection to modify plant and animal traits, and create environmental changes that could affect animal performance.