Evolutionary advances in the higher fungi.

Abstract

In this report the phrase 'evolutionary advances' is used in three ways: 1. to describe monophyletic changes perceived within a lineage; 2. to describe evolutionary sequences that appear to have become parallel/convergent; 3. to describe major transitions inferred between primary taxa. In monophyletic evolution the changes occur within a specific lineage that arises from a common ancestor, e.g., modern Man, horses, rusts. In parallel/convergent evolution different lineages respond similarly over time to environmental challenges and opportunities and come to acquire a great deal of comparability (e.g., Webster, 1987). Such lineages may be designated as separate taxa, e.g., similarities in marsupial and placental carnivores, or, if the polyphyleticism is cryptic, as a collective taxon, e.g., Aves, the class of birds, the obsolete Amentiferae for catkin bearing plants, the Gasteromycetes, and lichens. In major transitions there are significant paradigm shifts in which evolutionary changes from one predominant life style pattern to another are accompanied by increases in complexity (see Smith & Szatháry, 1995), e.g., symbiosis, the water to land transition, the changes between the phyla of land fungi. Three particular terms are used in evaluating evolutionary relationships (Moore, 1996a): homology, paramology, and analogy. Homology, from Darwin's theory of common descent, is the phenomenon of having a common historical origin but not necessarily the same final structure or function (e.g., vertebrate forelimbs). Paramology (Moore, 1971) applies to inferred relationships in evolutionary schemes based on contemporary forms that lack fossil antecedents, e.g., the various phylogenetic interpretations of prokaryotes, algae, and fungi; Boekhout et al. (1993) have evaluated the taxonomic resolution of a variety of morphologic, biochemical, physiological, and molecular characters (Table 1). Analogy is generally applied to similar forms that are unrelated, e.g., insect/vertebrate wings; prokaryote/eukaryote flagella. It should also be borne in mind that, in a given taxon, biotrophism (Coffey, 1975) is an advanced character (Health, 1987) over, respectively, weaker parasitism, symbiotism, commensalism, and freeliving and that seemingly simple or less differentiated forms can be, and more than likely than not are, reduced, polyphyletic, and specialized rather than ancient and rudimentary, e.g., yeasts (Hoog et al., 1988; Kurtzman & Fell, 1996; Moore, 1988b; 1996a).