Why life-cycle studies?: Implications in the taxonomy of rust fungi（Uredinales）

Abstract

　Seven hundred and sixty-three rust species are known in Japan. One hundred and four species are long-cycled autoecious in their life cycle, whereas one hundred and sixteen species are microcyclic. One hundred and ninety-two species possess a heteroecious life cycle, with 161 species having been experimentally proven in Japan. Rust fungus species can better be recognized and separated from close allies by host specificity and life-cycle differences. This species recognition is considered to be congruent with the most widely accepted “Biological Species Concept.” Rust species recognized as such are associated with a disjunction in phenetic character-state co-variation. Therefore, the detection of disjunction in phenetic character-state co-variation can be a good estimate of species differences in rust fungi. Delimiting and characterizing rust species by host specificity and life-cycle can provide reasonable interpretations of rust fungus phylogeny estimated by molecular phylogenetic methods.