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Title: Evidence for a population expansion in the West Nile virus vector Culex tarsalis.

Authors: Venkatesan, Meera; Westbrook, Catherine J; Hauer, M Claire; Rasgon, Jason L

Published In Mol Biol Evol, (2007 May)

Abstract: 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 F(S), 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.

PubMed ID: 17339636 Exiting the NIEHS site

MeSH Terms: Animals; Biological Evolution; Culex*/enzymology; Culex*/genetics; Culex*/virology; DNA, Mitochondrial; Gene Flow; Genetic Variation; Haplotypes; Insect Vectors*/genetics; Insect Vectors*/virology; Linkage Disequilibrium; Microsatellite Repeats; Molecular Sequence Data; NADH Dehydrogenase/genetics; Phylogeny; Polymorphism, Genetic; Population Dynamics; United States; West Nile Fever/transmission; West Nile Fever/virology; West Nile virus

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