Comparative analysis of sequences and secondary structures of the rRNA internal transcribed spacer 2 (ITS2) in pollen-beetles of the subfamily Meligethinae (Coleoptera, Nitidulidae): potential use of slippage-derived sequences in molecular systematics.

A comparative analysis of ITS2 sequences and secondary structures in 89 species of pollen beetles of thesubfamily Meligethinae (Coleoptera, Nitidulidae) was performed. The ITS2 folding pattern was highlyconserved and comparable with the general model proposed for eukaryotes. Simple sequence repeats(SSRs) were responsible for most of the observed nucleotide variability (1–3%) and length variation(359–459 bp). When plotted on secondary structures, SSRs mapped in expansion segments positionedat the apices of three ITS2 helices (‘A’, ‘B’ and ‘D1’) and appeared to have evolved under mechanismsof compensatory slippage. Homologies among SSRs nucleotides could not be unambiguously assigned,and thus were not useful to resolve phylogeny. However, slippage-derived motifs provided some preliminarygenetic support for newly proposed taxonomic arrangements of several genera and subgeneraof Meligethinae, corroborating existing morphological and ecological datasets.