Fig. 5.

Maximum likelihood phylogeny of the resistance locus rsk. The alleles are split into two major groups, with Sk-2 (marked with red text) in one and Sk-3 (blue text) in the other. Sk-2-resistant strains (marked with red dots) cluster with Sk-2, but Sk-3-resistant strains (blue dots) are found in both groups. All Neurospora sitophila strains have similar alleles at the rsk locus, and there is no clustering depending on whether they are Sk-1 killers (orange text) or sensitives (black text). Most N. intermedia and N. crassa strains have been tested for resistance against Sk-2 and Sk-3, but this is not possible in most other Neurospora species, due to poor sexual compatibility. An exception is N. metzenbergii, where spore killing is observed in crosses with included strains