Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 7/31/1996
Publication Date: N/A
Technical Abstract: We used a mathematical competition model to quantify contributions of the parameters: infection efficiency (E), lesion carrying capacity (K), competitive ability for pustule formation (alpha), sporulation efficiency (b), maximum sporulation capacity/leaf (M), and competitive ability for spore production (beta) to relative fitness of coexisting strains of Puccinia graminis f. sp. tritici on wheat leaves. The population density- and frequency-dependence of each parameter's contribution to fitness was determined. An advantage to a pathogen strain in E or M yielded an advantage in fitness independent of pathogen density. The fitness advantage conferred by a greater b decreased with increasing density, whereas the advantage conferred by greater K, alpha, or beta increased with density. A frequency-dependent fitness advantage was conferred by an advantage in alpha or beta, but not E, K, b, or M. These results illustrate that differences in fitness parameters can lead to density- and frequency-dependent selection in microbial populations on plants.