Tham khảo tài liệu 'international perspectives on global environmental change part 8', khoa học tự nhiên, công nghệ sinh học phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Effect of Environmental Change on Secondary Metabolite Production in Lichen-Forming Fungi 199 But there were no changes in thallus dimensions or nitrogen fixation activity. A shift in secondary metabolism to allow survival in a particular habitat may promote changes in species and therefore functional attributes of phenotype. One of the functional changes of lichen-fungi dealt with in this chapter is that of secondary metabolite production. To some extent fungal secondary metabolites reflect taxonomy but some studies have suggested that secondary metabolites may also be influenced by environmental change. Environmental changes influence many cellular activities and also serve as triggers for a change in mode of reproduction influencing the entire biology of the species. Since most species have diagnostic compounds that are consistently produced because of genetic inheritance and species adaptation to particular niches chemical diversity can be correlated with taxonomy. The chemical correlation with taxonomy is referred to as chemotaxonomy reviewed by Hawksworth 1976 Frisvad et al. 2008 . Knowledge of species taxonomic diversity is a first clue to understanding the polyketide diversity in any habitat. Ramalina americana was split into two different species R. culbersoniorum and R. americana based on secondary metabolite and nucleotide sequence divergence LaGreca 1999 . The Cladonia chlorophaea complex contains at least five chemospecies which are named and determined by the secondary metabolite produced Culberson C. F. et al. 1977a . Other examples exist to show variability among individuals within the same geographic area. Secondary metabolites may also vary even within chemospecies. For example the diagnostic metabolite for C. grayi is grayanic acid and for C. merochlorophaea is merochlorophaeic acid. However these species may or may not produce fumarprotocetraric acid a polyketide that is considered to be an accessory compound since it is not consistently .
