Resolving genetic diversity in Australasian Culex mosquitoes: incongruence between the mitochondrial cytochrome c oxidase I and nuclear acetylcholine esterase 2.
Insects that vector pathogens are under constant surveillance in Australasia although the repertoire of genetic markers to distinguish what are often cryptic mosquito species remains limited. We present a comparative assessment of the second exon-intron region of the acetylcholine esterase 2 gene (ace-2) and the mitochondrial DNA cytochrome c oxidase I (COI) using two closely related Australasia mosquitoes Culex annulirostris and Culex palpalis. The COI revealed eight divergent lineages of which four were confirmed with the ace-2. We dissect out the nuclear chromosomal haplotypes of the ace-2 as well as the exon-intron regions by assessing the protein's tertiary structure to reveal a hypervariable 5'-exon that forms part of an external protein loop and displays a higher polymorphic rate than the intron. We retrace the evolutionary history of these mosquitoes by phylogenetic inference and by testing different evolutionary hypotheses. We conclude that DNA barcoding using COI may overestimate the diversity of Culex mosquitoes in Australasia and should be applied cautiously with support from the nuclear DNA such as the ace-2. Together the COI and ace-2 provide robust evidence for distinct cryptic Culex lineages--one of which correlates exactly with the southern limit of Japanese encephalitis virus activity in Australasia.
Hemmerter
Stéphane
S
Institute for the Biotechnology of Infectious Diseases, University of Technology Sydney, Ultimo, NSW 2007, Australia. stephane.hemmerter@uts.edu.au
Slapeta
Jan
J
Beebe
Nigel W
NW
D000110:Acetylcholinesterase / Q000235:genetics*; D000818:Animals; D044362:Australasia; D001499:Bayes Theorem; D003465:Culex / Q000145:classification / Q000201:enzymology / Q000235:genetics*; D004272:DNA, Mitochondrial / Q000235:genetics; D004331:Drosophila melanogaster / Q000201:enzymology / Q000235:genetics; D003576:Electron Transport Complex IV / Q000235:genetics*; D019143:Evolution, Molecular; D005819:Genetic Markers; D014644:Genetic Variation; D005843:Geography; D006239:Haplotypes; D019476:Insect Proteins / Q000235:genetics; D016013:Likelihood Functions; D008928:Mitochondria / Q000235:genetics; D010802:Phylogeny; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D013045:Species Specificity
D004272:DNA, Mitochondrial; D005819:Genetic Markers; D019476:Insect Proteins; D003576:Electron Transport Complex IV; D000110:Acetylcholinesterase