Aedes aegypti in North America (Microsatellite and SNP array)

The Aedes aegypti mosquito first invaded the Americas about 500 years ago
and today is a widely distributed invasive species and the primary vector
for viruses causing dengue, chikungunya, Zika, and yellow fever. Here we
test the hypothesis that the North American colonization by Ae. aegypti
occurred via a series of founder events. We present findings on genetic
diversity, structure, and demographic history using data from 70 Ae.
aegypti populations in North America genotyped at 12 microsatellite loci
and/or ~20,000 single nucleotide polymorphisms (SNPs), the largest genetic
study of the region to date. We find evidence consistent with a
colonization driven by serial founder effect (SFE), with Florida as the
putative source for a series of westward invasions. This scenario was
supported by 1) a decrease in the genetic diversity of Ae. aegypti
populations moving west, 2) a correlation between pairwise genetic and
geographic distances, and 3) demographic analysis based on allele
frequencies. A few Ae. aegypti populations on the west coast do not follow
the general trend, likely due to a recent and distinct invasion history.
We argue that SFE provides a helpful albeit simplified model for the
movement of Ae. aegypti across North America, with outlier populations
warranting further investigation.