Abstract: Three experiments were conducted to investigate how patterns of general and sexual development might be correlated with the formation of social and mating systems among four species of voles ( Microtus ) . Species included pine voles ( Microtus pinetorum ), prairie voles ( M. ochroqaster ), meadow voles ( M. pennsylvanicus ), and montane voles ( M. montanus ) . In Experiment 1, general and sexual development were monitored as voles...