The effective magnetoelastic coefficients B_i^eff are measured for epitaxial layers of Fe, Co, and Ni on Ir(100). Mechanical stress during film growth and stress during magnetization processes are measured directly by the optical cantilever curvature technique. Our results indicate that the effective magnetoelastic coupling coefficients B₁^eff and B₂^eff of Fe, Ni, and Co deviate from the respective bulk values, and we propose that strain may play an important role for this nonbulklike magnetoelastic behavior. The impact of the magnetoelastic coupling on the magnetic anisotropy is explored by magneto-optic Kerr effect measurements. The measurements reveal that the easy magnetization axis is in plane for Fe and Co layers on Ir(100). It changes from out of plane to in plane for Ni at about 15 monolayer with increasing film thickness. This spin reorientation transition can be well described by the measured magnetoelastic coupling coefficients. The result of nonbulklike magnetoelastic coupling is discussed in view of recent theoretical work on the calculation of magnetoelastic coupling in strained systems.