On or before December 31 of the first calendar year following a year of federal decennial census, it is the duty of the legislative branch of the unified government to reapportion or redistrict the seats of the legislative branch and the seats of the board of education of the unified government to comply with constitutional requirements. Districts reapportioned or redistricted under this section shall be relatively compact, undivided, representative of community interests, and as equal in population as reasonably practicable.