Democracy
The colonization of Mars may go along with advancements in social structures and leadership. Representative democracy is likly to be the most wanted kind of government.
With Elections
Just like on Earth the government of a martian society can be elected by the colonists.
Without Elections
Representative democracy can work without elections, as well. Modelled on the ancient athenian democracy the martian people can chose to selection the government members by lottery, which can be regarded as a more democratic principle. Unlike the athenian democracy the parliament on Mars allows every adult member of the martian community to be selected, including women.