There shall be a Public Service Commission, consisting of not less than three nor more than seven members, as the Legislature shall prescribe, whose term of office shall be six years, and whose compensation shall be fixed by the Legislature. Commissioners shall be elected by districts of substantially equal population as the Legislature shall provide. The powers and duties of such commission shall include the regulation of rates, service and general control of common carriers as the Legislature may provide by law. But, in the absence of specific legislation, the commission shall exercise the powers and perform the duties enumerated in this provision.