Determining the processes that drive the evolution of pathogen host range can inform our understanding of disease dynamics and the potential for host-shifts. In natural populations, patterns of host range could be driven by genetically based differences in pathogen infectivity or ecological differences in host availability. In northwestern Italy, four reproductively isolated lineages of the fungal plant-pathogen Microbotryum have been shown to co-occur on several species in the genus Dianthus. We carried out cross-inoculation experiments to determine whether patterns of realized host range in these four lineages were driven by differences in infectivity and to test whether there was evidence of a trade-off between host range and within-host reproduction. We found strong concordance between field patterns of host range and pathogen infectivity on different Dianthus species using experimental inoculation, indicating that infection ability is a major driving force of host range. However, we found no evidence of a trade-off between the ability to infect a wider range of host species and spore production on a shared host.

Data was collected in three cross inoculation experiments.  Methods are described in the linked paper.  Four data sets are available: 

"Experiment 1 cross inoculation infection and flowering data.xls" contains infection status and date of first flower for each individual plant in Experiment 1.

"Spores.xls" contains spore count data on each infected D. pavonius flower that flowered in the first year. 

"D. segueiri repeat experiments.xls" contains counts of infected and diseased plants in a repeat experiment of experiment 1. 

"Experiment 2 D. seguieri pops.xls" contains counts of infected and diseased plants of D. seguieri plants from eight different populations.  

There is a readme file in a separate tab in each excel file.