Molecular phylogeny of South African Anopheles, Aedes and Culex (Diptera: Culicidae) based on COI, ITS2 and 28S DNA sequences
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Date
2021-11
Authors
Whitehead, Liezl
Journal Title
Journal ISSN
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Publisher
University of the Free State
Abstract
Mosquitoes have a substantial impact on human and animal health as vectors of disease and consequently take a heavy toll on the economy. South Africa hosts a multitude of mosquito-borne pathogens, including numerous arboviruses and Plasmodium. Many pathogens are transmitted by species currently belonging to three genera, namely Aedes Meigen, 1818, Culex Linnaeus, 1758 and Anopheles Meigen, 1818. Mosquitoes have traditionally been classified by their morphology, which has produced several non-monophyletic taxa. However, the field of systematics has been revolutionised with the advent of molecular techniques, which allow researchers to gain novel insights into the hidden affiliations of taxa. Since few phylogenetic studies have focused on South African mosquitoes, the current study aimed to investigate the intrageneric relationships of South African Aedes, Culex and Anopheles species based on COI, ITS2 and 28S DNA sequences. Therefore, mosquitoes were sampled across various habitats within central South Africa, ranging from relatively pristine nature reserves to urban centres with substantial anthropological activity. Morphological variations of sampled specimens were noted and numerous morphotypes were sequenced for the three target DNA regions. The identities of sampled specimens were verified with BLAST queries and the generated sequences were incorporated into genus-specific multiple sequence alignments. The datasets included representatives of many major taxonomic subdivisions and all accessible South African species, which were obtained from international DNA repositories. Due to the limited availability of sequences, it was not possible to construct concatenated datasets consisting of all three target DNA regions. Therefore, the aim was rather to incorporate shared representative species within each of the independent COI, ITS2 and 28S datasets. These genus and gene-specific multiple sequence alignments were used to conduct maximum likelihood and Bayesian phylogenetic analyses. Several phylogenetic findings were corroborated by multiple gene regions and supported by the results of other authors. This included the polyphyly of several Aedes subgenera (Aedimorphus, Ochlerotatus and Stegomyia) and the non-monophyly of several Neomelaniconion species. The subgenus Culex was also often rendered non-monophyletic by two other subgenera (Barraudius and Oculeomyia) and similarly contained polyphyletic assemblages of Cx. pipiens, Cx. quinquefasciatus and the Pipiens Group. Finally, the current analyses also recovered non-monophyletic groupings of the subgenus Anopheles, the Laticorn Section and the Funestus Group within the genus Anopheles. These results emphasized consistent phylogenetic findings, revealing numerous challenges within the current systematic framework. Therefore, the study provided insight into the affiliations of numerous South African species, generated molecular and phylogenetic data for sampled individuals and provided distribution data for the associated specimens. These results expanded the foundation of phylogenetic and ecological data, which can be incorporated into other epidemiological, biogeographical and evolutionary investigations.
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Keywords
South Africa, Aedes, Culex, Anopheles, Molecular phylogeny, Mosquitoes, Dissertation (M.Sc. (Zoology and Entomology))--University of the Free State, 2021, Mosquitos -- South Africa