Detecting nucleotide additivity from direct sequences is a SNAP: An example from Sidalcea (Malvaceae)

Superimposed nucleotide additivity patterns (SNAPs) were detected from dire ct sequences of the nuclear ribosomal DNA internal transcribed spacers in a complex of perennial Sidalcea species (Malvaceae) from the Pacific Northwe st of the United States. Although only 2.8 % sequence variation exists amon g the eight ITS accessions, parsimony analysis identified two distinct line ages within this complex consistent with known ploidy levels. Six SNAPs wer e identified in a known tetraploid S.virgata, suggesting allopolyploid orig ins from diploid S. virgata and one of two hexaploid Sidalcea species. A do sage effect detected at all six SNAP sites is consistent with the unequal s ized parental genomes of allopolyploid S. virgata.