The distribution of genetic diversity in the Neofusicoccum parvum/N. ribis complex suggests structure correlated with level of disturbance

Plants and animals adapted to colonize disturbed sites might also be better invaders, but this phenomenon has not been widely considered in fungi. We investigated genetic diversity and structure amongst isolates of Neofusicoccum parvum, N. cordaticola, N. kwambonambiense and N. umdonicola that coexist sympatrically on a native tree, Syzygium cordatum, across its distribution in South Africa. Species composition varied among stands, with dominance of N. parvum in disturbed stands, and absence in undisturbed stands, where the other species dominated. N. parvum populations from trees planted in urban environments were more genetically diverse than populations from human disturbed stands of S. cordatum. Bayesian analysis clustered N. parvum isolates in three sub-populations, suggesting three sources of origin. These results support the hypothesis that as a generalist N. parvum will dominate human disturbed sites and trees in urban areas, indicating strong potential for invasion, and its spreading from non-native hosts to native S. cordatum, rather than vice versa.