Tada Juthayothin. Molecular phylogenetic study of culicine mosquitoes using the mitochondrial cytochrome oxidase I gene and the relationships with mosquito-borne flaviviruses . Master's Degree(Environmental Biology). Mahidol University. : Mahidol University, 2004.
Molecular phylogenetic study of culicine mosquitoes using the mitochondrial cytochrome oxidase I gene and the relationships with mosquito-borne flaviviruses
Abstract:
Phylogenetic studies of mosquitoes in the Family Culicidae and in the Genus
Culex (subfamily Culicinae) were conducted using the mitochondrial cytochrome
oxidase subunit I (COI) gene. The COI genes (642 bp) of mosquitoes were directly
sequenced and 26 mosquito COI sequences were obtained from the GenBank
database. Due to multiple substitution and substitution bias in the sequences, which
reduced the phylogenetic signal from ancestors, it was impossible to determine the
relationships between mosquitoes based on nucleotide analysis. The relationships
were, however, recovered from amino acid analysis in which the neighbor-joining
method gave better resolution than the maximum parsimony method. This was
because of the low number of informative sites in MP analysis due to little variation in
COI amino acids of mosquitoes. Phylogenetic study among mosquitoes in the Family
Culicidae showed that members of the Subfamily Toxorhynchitinae cluster within the
clade of the Subfamily Culicinae. In the Subfamily Anophelinae clade, Anopheles
mosquitoes cluster together with Chagasia bathana as sister species. Subfamily
Culicinae was divided into two groups, the Aedes and Culex groups. The Aedes cluster
was composed of Aedes and Armigeres mosquitoes whereas the Culex cluster was
composed of Culex and Mansonia mosquitoes. The relationships among mosquitoes in
the Genus Culex were investigated in three subgenera, Culex, Culiciomyia and
Eumelanomyia, and the results showed that members of the Subgenus Eumelanomyia
branched off first and were distantly related to the others whereas the Subgenus
Culiciomyia grouped in the clade of the Subgenus Culex and was therefore considered
to be closely related to Subgenus Culex. The relationships among members in the
Subgenus Culex were correlated with those derived from morphological
characteristics, in which members of the vishnui subgroup, i.e., Cx. vishnui and Cx.
tritaeniorhynchus, grouped together. The two most similar Culex mosquitoes, Cx.
gelidus and Cx. whitmorei clustered together. Mosquito-borne flavivirus phylogeny
was determined using the envelope protein gene, and the nonstructural protein 3 and 5
genes. There were two distinct groups based on their vectors, Aedes and Culex
mosquitoes. Comparison of mosquito phylogeny with flavivirus phylogeny revealed
that coevolution between mosquitoes and flaviviruses may have occurred before Aedes
and Culex separation. After separation, differences in mosquito behavior may have
driven flavivirus evolution