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 mo squitoes in Thailand. A total of 43 subclone PCR fragments of the size expected for reverse transcriptase of copia-like elements was isolate d from Anopheles dirus (Peyton & Harrison) subspecies A, Anopheles mac ulatus (Theobald) subspecies E, Anopheles nivipes (Theobald), and Anop heles subpictus Grassi. Sequence analysis of subclones confirmed the i dentity of these sequences as copia-like reverse transcriptase sequenc es. The sequences displayed varying degrees of sequence heterogeneity, in contrast to the limited diversity seen in copia-like elements in D rosophila. Phylogenetic analysis of the amino acid sequences of the su bclones showed that the majority of the retroelements were clustered t ogether, implying that sequence divergence during vertical transmissio n of the copia-like retrotransposons has been a major factor in the ev olution 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 evol ution.