Lineage divergence detected in the malaria vector Anopheles marajoara (Diptera: Culicidae) in Amazonian Brazil

Previous analysis based on the complete mtDNA COI gene sequences detected paraphyly in the Neotropical malaria vector A. marajoara. To test this hypothesis, population structure was compared using multiple molecular markers, and genealogical trees based on a concatenated (white + 3’ COI sequences) dataset from Amazonian Brazil were examined. Distinct A. marajoara lineages were detected by combined genealogical analysis and were also supported among COI haplotypes using a median joining network and AMOVA, with time since divergence during the Pleistocene (<100,000ya). Lineage 1 was present in all localities, whereas lineage 2 was restricted mainly to the west. Mismatch distributions for both lineages were bimodal, likely due to multiple colonization events and spatial expansion (~798 – 81,045ya). In contrast, both nDNA data sets (white gene sequences with or without the retention of the 4th intron, and ITS2 sequences and length) detected a single A. marajoara lineage. Strong support for combined data suggests recent divergence detectable only by the faster evolving mtDNA. The “Folmer region” identified a single taxon (3% divergence threshold). To test the utility of the barcode region pairwise differentiation of COI fragments were examined. COI sequences at the 3' end were more variable, demonstrating significant pairwise differentiation (3.82%) compared to the more moderate 2.92% detected by the Folmer region. A within subgenus threshold of >2% may be more appropriate among sister taxa in cryptic anopheline complexes than the standard 3%. Differences in demographic history and climatic changes may have contributed to mtDNA lineage divergence in A. marajoara.