ancient relict that was present in Gondwanan rainforests and today grows across the Southern Hemisphere. N. cunninghamii is most closely related to N. moorei, the other species of evergreen Nothofagus endemic to Australia. The two likely evolved from a Tertiary ancestor. Due to cooling since the Tertiary period, leaves may have been pressured to evolve to smaller sizes in colder environments. This may explain the evolution toward smaller leaves than their ancestor as well as the northern boundary for N. cunnninghamii where it is replaced by the larger-leafed N. moorei in warmer Northern environments. Threats Myrtle wilt, a parasitic fungus, (Chalara australis) attacks myrtle beech when the air or water-borne spores settle on open wounds. Myrtle wilt only infects N. cunninghamii and is a deadly pathogen that infects roots and trunks. It causes tree crown wilting and foliage to turn brown and yellow. C. australis can spread to neighbouring trees through roots, creating large patches of dead trees. Due to higher rates of root graphing, the fungus is more prolific in pure rainforest than mixed forest. Dead stands of this dominant species can completely change the ecosystem in cool temperate rainforests. Infection of myrtle wilt can also increase the impact of other threats such as the ambrosia beetle (Platypus subgranosus). Ambrosia beetles bore holes into myrtles producing a dust called frass. Frass can contribute to the spread of the C. australis and increase available wounds susceptible to the fungus. Myrtle wilt is a natural disease of N. cunninghamii; research points to a low rate of mortality due to the fungus in undisturbed forest (0.61%) but drastic increase in mortality in areas with human disturbance. In recent years, myrtle wilt has become a serious problem due to poor logging practices. Rates of myrtle wilt are increased along roads, walking tracks, and logging areas likely due to decreased protection against elements, increasing the potential for injury and infection. Temperate myrtle beech rainforests are not protected in many areas of Tasmania and are threatened by mining and logging. Due to a lack of protection, these rainforest species continue to be threatened by extractive activities. Due to their low fire resistance, myrtle beech are also threatened by wildfires of increasing intensity and frequency due to climate change. Climate change also increases the threat of myrtle wilt as the fungus is more fit in warmer environments. Uses and cultivation It is an excellent cabinetry timber