Evidence of evolution

What evidence is there to prove evolution exists? Genetics and behavioural comparisons, among many others, have delivered evidence to support evolution. Genetic variation between individuals of the same species gives rise to different behavioural patterns. For example, the common field cricket. Why do males in one population call more than those in another population? Also, why do females in one population lay more eggs than those in another population? It is possible to find the genes that are responsible for these behavioural differences.