Submitted to: Inoculum
Publication Type: Abstract Only
Publication Acceptance Date: June 1, 2005
Publication Date: August 1, 2005
Citation: Szabo, L.J. 2005. Deciphering species complexes and the evolutionary implications. Inoculum. 56:56. Technical Abstract: Species complexes are common among the Uredinales, which often results in confusion regarding the biology of these fungi. Two examples that are currently being studied are the heteroecious, macrocyclic rust fungi Puccinia andropogonis and P. coronata. P. andropogonis has a narrow telial host range (prairie grasses Andropogon gerardii and Schizachyrium scopari) and a broad aecial host range that spans seven plant families. In contrast, P. coronata has a broad telial host range (Aveneae, Poeae, and Triticodae) and a narrow aecial host range of a single genus (Rhamnus). The nuclear ribosomal region including the complete ITS and 5' end of the LSU was analyzed for 34 samples of P. andropogonis and 48 samples of P. coronata. Phylogenetic analysis divided the P. andropogonis complex into eight well-supported groups that were divided along telial and aecial lines. These results indicate that there were two evolutionary events, the first separation on the telial hosts followed by radiation onto different aecial hosts. Speciation follows taxonomic classification of aecial families. Analysis of DNA sequence data divided the P. coronata complex into seven well supported groups. Results indicate that speciation in the P. coronata complex has occurred primarily through radiation onto different telial hosts.