Observed number of partial resistance scores by host lineage (n=200) for sympatric within population cross-inoculations, in relation to the expected number of partials (n=1000) based on marginal frequencies for the same lineages in allopatric populations. The section of rows labeled “Pathogen” represents pathogen lineages from the six populations tested on sympatric and allopatric hosts, and correspondingly “Host” represents host families tested using sympatric and allopatric pathogens. Chi-square is for a 2×2 contingency test with 1 degree of freedom.