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Open Access Research

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

Sascha N McKeon1, Margaret A Lehr2, Richard C Wilkerson3, John F Ruiz3, Maria A Sallum4, Jose BP Lima5, Marinete M Povoa6 and Jan E Conn17*

Author Affiliations

1 Department of Biomedical Sciences, School of Public Health, State University of New York-Albany, Empire State Plaza, Albany, NY 12201 USA

2 Department of Biology, 120A Marsh Life Sciences Building, University of Vermont, Burlington, VT 05405, USA

3 Department of Entomology, Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, MD 20910 USA

4 Department of Epidemiology, Universidade de Sao Paulo, 715 - Cerqueira Cesar 01246-904 Sao Paulo, Brazil

5 Laboratório de Fisiologia e Controle de Artropodes Vetores, IOC-Fiocruz, 4365 - Manguinhos, Rio de Janeiro, Brazil

6 Laboratório de Pesquisas Básicas em Malaria, Instituto Evandro Chagas, Secretaria de Vigilância em Saúde/MS, Br 316, Km 7, s/n, CEP 67.030-000, Ananindeua, Para, Brazil

7 The Wadsworth Center, Griffin Laboratory, New York State Department of Health, 5668 State Farm Road, Slingerlands, NY 12159, USA

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Malaria Journal 2010, 9:271  doi:10.1186/1475-2875-9-271

Published: 7 October 2010

Abstract

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 Amapá 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.

Conclusions

Strong support for combined data with significant differentiation detected in the COI and absent in the nDNA suggest that the divergence is recent, and detectable only by the faster evolving mtDNA. 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.