  We measure the transport properties of mechanically strained single crystals
of BaFe$_{2}$(As$_{1-x}$P$_{x}$)$_{2}$ over a wide range of $x$. The N\'eel
transition is extremely sensitive to stress and this sensitivity increases as
optimal doping is approached, even though the transition itself is strongly
suppressed. Furthermore, we observe significant changes in the superconducting
transition temperature with applied strain, which mirror changes as a function
of the composition $x$. These experiments are a direct illustration of the
intimate coupling between different degrees of freedom in iron-based
superconductors, revealing the importance of magneto-elastic coupling to the
magnetic and superconducting transition temperatures.
