Evolution and phylogenetic information content of the ITS-1 region in the tiger beetle Cicindela dorsalis

Sequence divergence in the internal transcribed spacer region 1 (ITS-1) ofthe ribosomal DNA locus was assessed in subspecies of the coastal NorthAmerican tiger beetle, Cicindela dorsalis. The spacer region was amplifiedusing the polymerase chain reaction and cloned for sequencing. Of a totalof 50 clones obtained from 12 specimens, 42 clones were different in atleast one nucleotide position. In a parsimony analysis of these sequences,the main phylogenetic distinction was found to separate sequences from theGulf of Mexico and the Atlantic Ocean. Within these two assemblagesphylogenetic resolution was low, and the variation within individuals wasalmost as high as the variation within the entire lineage. The pattern ofsequence variation suggests the existence of two forms of the ITS-1 thatare maintained on different chromosomes. Polymorphisms of limitedgeographical distribution could be detected, and 41 additional clones werepartly sequenced, to assess the geographic distribution of thesepolymorphisms in more detail. In a population aggregation analysis, thegeographic pattern of ITS-1 distribution was basically congruent with thatobtained in earlier studies from mitochondrial DNA in the same C. dorsalispopulations.