Lineage Divergence Detected in the Malaria Vector Anopheles marajoara (Diptera: Culicidae) in Amazonian Brazil
WALTER REED ARMY INST OF RESEARCH SILVER SPRING MD DEPT OF ENTOMOLOGY
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Background Cryptic species complexes are common among anophelines. Previous phylogenetic analysis based on the complete mtDNA COI gene sequences detected paraphyly in the Neotropical malaria vector Anopheles marajoara. The Folmer region detects a single taxon using a 3 divergence threshold. Methods To test the paraphyletic hypothesis and examine the utility of the Folmer region, genealogical trees based on a concatenated white 3 COI sequences dataset and pairwise differentiation of COI fragments were examined. The population structure and demographic history were based on partial COI sequences for 294 individuals from 14 localities in Amazonian Brazil. 109 individuals from 12 localities were sequenced for the nDNA white gene, and 57 individuals from 11 localities were sequenced for the ribosomal DNA rDNA internal transcribed spacer 2 ITS2. Results 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 100,000 ya. 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. 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 - 81,045 ya. There appears to be gene flow within, not between lineages, and a partial barrier was detected near Rio Jari in Amapa state, separating western and eastern populations. 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.
- Medicine and Medical Research