How does coevolution cease in grafted trees?

Coevolution in grafted trees ceases because the grafting process combines different plant species or varieties, effectively breaking the natural evolutionary interactions between them. The grafted sections often do not share the same genetic material or ecological niches, leading to a lack of reciprocal evolutionary pressures. Additionally, the physical and physiological separation of rootstock and scion limits their ability to adapt and respond to each other's traits or environmental changes, resulting in a static relationship rather than a dynamic coevolutionary one.