Conserved gene arrangement in the mitochondrial genomes of barklouse families Stenopsocidae and Psocidae

Abstract

Substantial variation in gene organization and arrangement has been reported for sequenced mitochondrial (mt) genomes from the suborders of the insect order Psocoptera. In this study we sequenced the complete mt genome of Stenopsocus immaculatus, the first representative of the family Stenopsocidae from the suborder Psocomorpha. Relative to the ancestral pattern, rearrangements of a protein-coding gene (nad3) and five tRNA genes (trnQ, trnC, trnN, trnS1, trnE) were found. This pattern was similar to that of two barklice from the family Psocidae, with the exception of the translocation of trnS1, trnE and trnI. Based on comparisons of pairwise breakpoint distances of gene rearrangements, gene number and chromosome number, it was concluded that mt genomes of Stenopsocidae and Psocidae share a relatively conserved pattern of gene rearrangements; mt genomes within the Psocomorpha have been generally stable over long evolutionary history; and mt gene rearrangement has been substantially faster in the booklice (suborder Troctomorpha) than in the barklice (suborders Trogiomorpha and Psocomorpha). It is speculated that the change of life history and persistence of unusual reproductive systems with maternal inheritance contributed to the contrasting rates in mt genome evolution between the barklice and booklice.

Keywords

• gene rearrangement|mitochondrial genome|Psocoptera|Stenopsocidae|TDRL model