Oxygen isotope (^{16}O/^{18}O) effects (OIEs) on the superconducting transition (T_c), the spin-glass ordering (T_g), and the antiferromagnetic ordering (T_N) temperatures were studied for Y_1-xPr_xBa_2Cu_3O_7-delta as a function of Pr content (0.0le
q x leq 1.0). The OIE on T_c increases with increasing x up to xapprox0.55, where superconductivity disappears. For decreasing x the OIEs on T_N and T_g increase down to xapprox 0.7 where antiferromagnetic order and down to xapprox0.3 where spin-glass behavior vanish, respectively. The OIEs on T_g and T_N are found to have {it opposite signs} as compared to the OIE on T_c. All OIEs are suggested to arise from the isotope dependent mobility (kinetic energy) of the charge carriers.
