Sequence heterogeneity in copia-like retrotransposons in Anopheles (Diptera: Culicidae) in Thailand

Degenerate primers and the polymerase chain reaction (PCR) detected a conserved region of copia-like reverse transcriptase from Anopheles mosquitoes in Thailand. A total of 43 subclone PCR fragments of the size expected for reverse transcriptase of copia-like elements was isolated from Anopheles dirus (Peyton & Harrison) subspecies A, Anopheles maculatus (Theobald) subspecies E, Anopheles nivipes (Theobald), and Anopheles subpictus Grassi. Sequence analysis of subclones confirmed the identity of these sequences as copia-like reverse transcriptase sequences. The sequences displayed varying degrees of sequence heterogeneity, in contrast to the limited diversity seen in copia-like elements in Drosophila. Phylogenetic analysis of the amino acid sequences of the subclones showed that the majority of the retroelements were clustered together, implying that sequence divergence during vertical transmission of the copia-like retrotransposons has been a major factor in the evolution of copia-like retroelements in Anopheles species. Additionally, there is evidence that horizontal transfer of this transposon group among certain divergent taxa also may have played a role in their evolution.