Evidence for a population expansion in the West Nile Virus vector Culex tarsalis

Meera Venkatesan, Catherine J. Westbrook, M. Claire Hauer, Jason L. Rasgon

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37 Scopus citations


Population genetic structure of the West Nile Virus vector Culex tarsalis was investigated in 5 states in the western United States using 5 microsatellite loci and a fragment of the mitochondrial reduced form of nicotinamide adenine dinucleotide dehydrogenase 4 (ND4) gene. ND4 sequence analysis revealed a lack of isolation by distance, panmixia across all populations, an excess of rare haplotypes, and a star-like phylogeny. Microsatellites revealed moderate genetic differentiation and isolation by distance, with the largest genetic distance occurring between populations in southern California and New Mexico (F ST = 0.146). Clustering analysis and analysis of molecular variance on microsatellite data indicated the presence of 3 broad population clusters. Mismatch distributions and site-frequency spectra derived from mitochondrial ND4 sequences displayed pattern's characteristic of population expansion. Fu and Li's D* and F*, Fu's FS, and Tajima's D statistics performed on ND4 sequences all revealed significant, negative deviations from mutation-drift equilibrium. Microsatellite-based multilocus heterozygosity tests showed evidence of range expansion in the majority of populations. Our results suggest that C. tarsalis underwent a range expansion across the western United States within the last 375,000-560,000 years, which may have been associated with Pleistocene glaciation events that occurred in the midwestern and western United States between 350,000 and 1 MYA.

Original languageEnglish (US)
Pages (from-to)1208-1218
Number of pages11
JournalMolecular biology and evolution
Issue number5
StatePublished - May 2007

All Science Journal Classification (ASJC) codes

  • Ecology, Evolution, Behavior and Systematics
  • Molecular Biology
  • Genetics


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