Population dynamics at an invasive front: Aedes aegypti in the American Southwest

Project Summary/ Abstract The mosquito species Aedes aegypti is the primary global vector of important human pathogens, including dengue and yellow fever viruses. The attributes that make Ae. aegypti an efficient vector of these pathogens - such as small flight ranges and the proclivity for human blood feeding - also impact the genetic structure of populations at local and regional scales. Aedes aegypti has recently re-emerged as a medically important insect in the (semi)arid American southwest (ASW, California, Arizona, New Mexico, Nevada, and western Texas), and populations are rapidly dispersing along a northward gradient. This proposal aims to investigate the structural properties of localized and regional Ae. aegypti population networks in this unique landscape to identify weaknesses and breakpoints in (sub)population connectivity which can inform mosquito control interventions. Our central hypothesis is that Ae. aegypti population dynamics in the ASW are best explained by a core-satellite metapopulation framework in which large urban centers maintain genetically diverse and stable populations (i.e., cores) while connectivity (i.e., gene flow) and invasion of satellites outside of cores is best explained by distance to a source, size of urbanized sites, and density of human populations. To investigate population structure across the ASW, we will systematically sample individuals from urban centers of varying human population densities, genotype individuals using a single-nucleotide polymorphism array (SNP-chip), and then use a combination of landscape genetic approaches and network analyses to quantify population connectivity and determine the influence of commerce (i.e., roads) systems on the structure of ASW Ae. aegypti populations. To investigate population structure within ASW cities, we will first intensely and systematically sample individuals from multiple locations and time points within four urban cores with historical, established, and recently invaded Ae. aegypti populations. We will then genotype individuals using whole genome sequencing and will analyze networks using persistent homology approaches to determine the extent to which population structure at local scales is driven by founder effects (e.g., time since invasion), physical barriers to random mating (e.g., site fidelity), and individual limits of dispersal (e.g., kinship networks). Our results will provide a novel and innovative assessment of Ae. aegypti population biology and invasion dynamics at multiple spatial scales, which can better guide mosquito control intervention efforts in the region.