What was the major cause of the punic wars in ancient rome?

Struggle for dominance over Mediterrenian between Rome and Carthage was the primary cause of the Punic Wars in Ancient Rome that is the shortest answer

The main cause of the Punic Wars was the conflicts of interest between the existing Carthaginian Empire and the expanding Roman Republic. The Romans were initially interested in expansion via Sicily (which at that time was a cultural melting pot), part of which lay under Carthaginian control.