Chemosystematics and Ecology of Lichen-Forming Fungi

Abstract

Recent years have seen a renaissance of interest in research into the life of the lichen, that most familiar of all textbook examples of symbiosis, a fungus and an alga living together. The systematics of the lichen fungi has shifted its base from descriptive morphology alone to the chemistry of met abolic end products as an additional and fertile source of data to explain relationships. Today, chemistry is more intimately involved in the theoreti cal systematics and even in the routine identification of specimens of the lichen fungi than of any other group of plants. The present level of sophis tication in the study of the chemistry of the lichen fungi has unfortunately not been matched in the study of other aspects of the biosystematics of these plants. Cultures suitable for genetic experiments are still not possible and even no unequivocal chromosome counts exist. As a consequence, chemical and ecological data that have been gathered from "natural experi ments" and that could not at present have been obtained from herbarium or laboratory studies take on increased significance as they give insight into the nature of variation in populations. In this review I shall try, not only to sketch the present status of chemosystematics and associated ecology in the study of the lichen fungi, but also to outline something of the peculiar biol ogy of these double plants, answering where possible the questions that I have come to anticipate from intelligent biologists. THE LICHEN-FORMING FUNGI

The Dynamic Discipline of Species Delimitation: Progress Toward Effectively Recognizing Species Boundaries in Natural Populations

“…The use of chemistry in lichen taxonomy has been discussed in detail in numerous reviews (Lumbsch 1998a, b;Rogers 1989;Brodo 1986;Egan 1986;Leuckert 1985;Brodo 1978;Hawksworth 1976;Culberson 1969Culberson , 1970), and we refer readers to these valuable sources for a more comprehensive perspective on lichen chemistry. In short, extrolites (secondary metabolites) belong to various classes; the most common and diverse include depsides, depsidones, chlorinated xanthones, and anthraquinones (Lumbsch 2002;Culberson 1969).…”

Goodbye morphology? A paradigm shift in the delimitation of species in lichenized fungi

“…If no morphological or geographical differences between populations containing different extrolites are found, the taxonomic significance has been disputed, with some authors distinguishing them as species and others preferring to regard them as chemical races within a species. The use of chemistry has been discussed in detail in numerous reviews (e.g., Culberson 1969Culberson , 1970Hawksworth 1976;Brodo 1978;Leuckert 1985;Brodo 1986;Egan 1986;Rogers 1989;Lumbsch 1998a,b) and this is not reiterated here in detail. In addition to using the presence of substances, it has been proposed to arrange lichen substances into chemosyndromes of closely related substances (Culberson and Culberson 1976).…”

Effect of Environmental Change on Secondary Metabolite Production in Lichen-Forming Fungi

“…Ramalina siliquosa produces bands of six chemical races on the rocky coast of Wales at different distances from the oceanic spray (Culberson W. L. & Culberson C. F., 1967). Other groups of lichens also show similar habitat specific correlations such as Cladonia chlorophaea complex and Parmelia bolliana (Culberson W. L., 1970). The production of some secondary compounds, such as rhizocarpic acid, have been shown to correspond with increases in altitude (Rubio et al, 2002).…”