The genetic structure of Aedes aegypti populations is driven by boat traffic in the Peruvian Amazon

Abstract

In the Americas, as in much of the rest of the world, the dengue virus vector Aedes aegypti is found in close association with human habitations, often leading to high population densities of mosquitoes in urban settings. In the Peruvian Amazon, this vector has been expanding to rural communities over the last 10–15 years, but to date, the population genetic structure of Ae. aegypti in this region has not been characterized. To investigate the relationship between Ae. aegypti gene flow and human transportation networks, we characterized mosquito population structure using a panel of 8 microsatellite markers and linked results to various potential mechanisms for long-distance dispersal. Adult and immature Ae. aegypti (>20 individuals per site) were collected from Iquitos city and from six neighboring riverine communities, i.e., Nauta, Indiana, Mazan, Barrio Florida, Tamshiaco, and Aucayo. FST statistics indicate significant, but low to moderate differentiation for the majority of study site pairs. Population structure of Ae. aegypti is not correlated with the geographic distance between towns, suggesting that human transportation networks provide a reasonable explanation for the high levels of population mixing. Our results indicate that Ae. aegypti gene flow among sub-populations is greatest between locations with heavy boat traffic, such as Iquitos-Tamshiaco and Iquitos-Indiana-Mazan, and lowest between locations with little or no boat/road traffic between them such as Barrio Florida-Iquitos. Bayesian clustering analysis showed ancestral admixture among three genetic clusters; no single cluster was exclusive to any site. Our results are consistent with the hypothesis that human transportation networks, particularly riverways, are responsible for the geographic spread of Ae. aegypti in the Peruvian Amazon. Our findings are applicable to other regions of the world characterized by networks of urban islands connected by fluvial transport routes.

Fine-scale population genetic structure of dengue mosquito vector, Aedes aegypti, in Metropolitan Manila, Philippines

“…The bar plots showed clear patterns of genetic admixture across mosquito populations. The interpretations of our Bayesian analysis are consistent with other population genetic studies [19,22,28,29,67,68] which demonstrated low genetic differentiation with no discernable genetic structures. The constant migration of mosquito populations facilitated by passive dispersal (e.g.…”

“…Our Bayesian analysis inferred sympatric multiple genetic clusters (K = 3 to K = 6) similar to the results reported by other population genetic studies with micro-geographic scales [19,22,67,68] and those conducted in the Philippines [28,29]. A possible explanation for this phenomenon could be the result of divergence from a single ancestry that produced multiple genetic clusters over time.…”

The influence of roads on the fine-scale population genetic structure of the dengue vector Aedes aegypti (Linnaeus)

“…For example, previous studies of Ae . aegypti revealed sympatric numerous genetic clusters (K = 3 to K = 16) from 30 km up to 2, 000 km [ 10 , 11 , 13 , 20 ], which might be due to the divergence from a single ancestry resulting into multiple genetic clusters over time and the random distribution of Ae . aegypti populations from nearby cities, regions or country.…”

The influence of roads on the fine-scale population genetic structure of the dengue vector Aedes aegypti (Linnaeus)

“…For example, previous studies of Ae. aegypti revealed sympatric numerous genetic clusters (K = to K= 16) from 30 km up to 2, 000 km [10][11]13,19], which might be due to the divergence from a single ancestry resulting into multiple genetic clusters over time and the random distribution of Ae. aegypti populations from nearby cities, regions or country.…”