The factor that contributed MOST to the evolution of diverse factors is differences in environment.
Differences in environmental conditions lead to different selective pressures, which drive natural selection and result in the adaptation of species to their specific habitats. While selective breeding programs and interbreeding with unrelated species can influence diversity, they are human-directed processes and do not account for the broad evolutionary changes seen in nature. Inheritance of learned behaviors contributes to diversity but is not a primary driver of evolution in the way that environmental differences are.