PHYLOGENETIC ANALYSIS OF HETEROTHALLIC NEUROSPORA SPECIES

We examined the phylogenetic relationships among five heterothallic sp ecies of Neurospora using restriction fragment polymorphisms derived f rom cosmid probes and sequence data from the upstream regions of two g enes, al-1 and frq. Distance, maximum likelihood, and parsimony trees derived from the data support the hypothesis that strains assigned to N. sitophila, N. discreta, and N, tetrasperma form respective monophyl etic groups, Strains assigned to N, intermedia and N. crassa, however, did not form two respective monophyletic groups, consistent with a pr evious suggestion based on analysis of mitochondrial DNAs that N. cras sa and N. intermedia may be incompletely resolved sister taxa, Trees d erived from restriction fragments and the al-1 sequence position N, te trasperma as the sister species of N. sitophila, None of the trees pro duced by our data supported a previous analysis of sequences in the re gion of the mating type idiomorph that grouped N, crassa and N. sitoph ila as sister taxa, as well as N, intermedia and N, tetrasperma as sis ter taxa, Moreover, sequences from al-1, frq, and the mating-type regi on produced different trees when analyzed separately, The lack of cons ensus obtained with different sequences could result from the sorting of ancestral polymorphism during speciation or gene flow across specie s boundaries, or both. (C) 1997 Academic Press.