Diversity and taxonomy of fungi infecting species of Adansonia (Baobab)

Abstract

Tree-infecting fungi can represent a major limiting factor in the growth and sustainability of natural forests and plantations. They can also result in major tree mortality events, such as the devastation of the American chestnut in the United States arising from the accidental introduction of the canker pathogen Cryphonectria parasitica. Investigating the distribution of macro and micro-organisms, including trees and the fungi that infect them, is broadly treated in the field of biogeography. Biogeography attempts to answer questions regarding the past and current distribution of organisms and the reasons for these distributions. This can inform predictions of future spread or extinction of organisms. In this review, we discuss the issue of vicarience vs. long distance dispersal to explain current distributions of trees and their associated fungi. As examples of host specific fungi, we consider the historical and current spread of the obligate biotrophic ascomycete fungus Cyttaria on Nothofagus, as well as some examples of the rust fungi. Less host specific associations are considered using Armillaria and the Botryosphaeriaceae as examples. The biogeography of the latter fungi is clearly more complicated to unravel. Finally, we consider the spread of host trees and fungi in a changing environment and the consequences of host shifts and range expansions