Utility of the white gene in estimating phylogenetic relationships among mosquitoes (Diptera: Culicidae)

The utility of a nuclear protein-coding gene for reconstructingphylogenetic relationships within the family Culicidae was explored.Relationships among 13 species representing three subfamilies and ninegenera of Culicidae were analyzed using a 762-bp fragment of codingsequence from the eye color gene, white. Outgroups for the study were twospecies from the sister group Chaoboridae. Sequences were determined fromclone PCR products amplified from genomic DNA, and aligned followingconceptual intron splicing and amino acid translation. Third codonpositions were characterized by high levels of divergence and biasednucleotide composition, the intensity and direction of which varied amongtaxa. Equal weighting of all characters resulted in parsimony andneighboring-joining trees at odds with the generally accepted phylogenetichypothesis based on morphology and rDNA sequences. The application ofdifferential weighting schemes recovered the traditional hypothesis, inwhich the subfamily Anophelinae formed the basal clade. The subfamilyToxorhynchitinae occupied an intermediate position, and was a sister groupto the subfamily Culicinae. Within Culicinae, the genera Sabethes andTripteroides formed an ancestral clade, while the Culex-Deinocerites andAedes- Haemagogus clades occupied increasingly derived positions in themolecular phylogeny. An intron present in the Culicinae- Toxorhynchitinaelineage and one outgroup taxon was absent in the basal Anophelinae lineageand the second outgroup taxon, suggesting that intron insertions ordeletions may not always be reliable systematic characters.