Abstract
Distribution of a family of tandemly repetitive sequences in Hemitaxonus japonicus (pYS family) was investigated among eight sawfly species and host races in the genus Hemitaxonus. High copy numbers of the repetitive sequences were detected in the two host plant races of H. japonicus, race Polystichum polyblepharum (race PP) and race P. tripteron (race PT), and H. sasayamensis, whereas a low copy number in H. minomensis. Comparison of the nucleotide sequences of the basic repeat units demonstrated a high degree of homology among the four tested species with high AT-rich sequences. Minor repeat units shorter than the consensus basic repeat unit of pYS family were found only in races PP and PT of H. japonicus. Analyses of their nucleotide sequences showed the occurrence of the host race specific sub-repeat units.
