What is Darwin Wallace theory?

It seems there might be a mix-up in the name; you may be referring to the theory of evolution by Charles Darwin, which explains how species evolve over time through natural selection. Darwin proposed that individuals with traits better suited to their environment are more likely to survive and reproduce, passing those advantageous traits to future generations. This process leads to gradual changes in species and the emergence of new ones. If you meant a different theory or individual, please provide more context.