Dating the origin and spread of specialization on human hosts in Aedes aegypti mosquitoes
- Princeton University, United States
- Université Joseph Ki-Zerbo, Burkina Faso
- Université du Sine Saloum El-Hâdj Ibrahima NIASS, Senegal
- University of Ghana, Ghana
- Connecticut Agricultural Experiment Station, United States
- Yale University, United States
- Verily Life Sciences, United States
Abstract
The globally invasive mosquito subspecies Aedes aegypti aegypti is a highly effective vector of human arboviruses, in part because it specializes in biting humans and breeding in human habitats. Recent work suggests that specialization first arose as an adaptation to long, hot dry seasons in the West African Sahel, where Ae. aegypti is forced to rely on human-stored water for breeding. However, rainfall patterns in this region have changed dramatically over the past 10-20 thousand years, and we do not yet know exactly when specialization occurred. Here we use whole-genome cross-coalescent analysis to date the emergence of human specialist populations in the Sahel and thus further probe the climate hypothesis. Importantly, we take advantage of the known migration of human-specialist populations out of Africa during the Atlantic Slave Trade to calibrate the coalescent clock and thus obtain a more precise estimate of the older evolutionary event than would otherwise be possible. We find that human-specialist mosquitoes diverged rapidly from ecological generalists approximately 5,000 years ago, which corresponds to the end of the African Humid Period-a time when the Sahara dried and water stored by humans became a uniquely stable, aquatic niche in the Sahel. We also use population genomic analyses to date a previously observed influx of human-specialist alleles into major West African cities, where mosquitoes tend to be more attracted to humans than in nearby rural populations regardless of climate. In this case, the characteristic length of tracts of human-specialist ancestry present on a generalist genetic background in Kumasi, Ghana and Ouagadougou, Burkina Faso suggests the change in behavior occurred during rapid urbanization over the last 20-40 years. Taken together, we show that the timing and ecological context of two previously observed shifts towards human biting in Ae. aegypti differ; climate was likely the original driver, but urbanization has become increasingly important in recent decades. Understanding the changing relationship between mosquitoes and humans over time is critical for predicting and managing burdens of mosquito-borne disease.
Data availability
Scripts and processed data are available at github.com/noahrose/aaeg-evol-hist. Raw genomic data are available in the NCBI SRA at accession PRJNA602495. Phasing reference panel is available at doi:10.5061/dryad.2bvq83btk.
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Dating the origin and spread of specialization on human hosts in Aedes aegypti mosquitoesDryad Digital Repository, doi:10.5061/dryad.2bvq83btk.
Article and author information
Author details
Andrea Gloria-Soria
Funding
Helen Hay Whitney Foundation
- Noah H Rose
New York Stem Cell Foundation
- Carolyn S McBride
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2023, Rose et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Dating the origin and spread of specialization on human hosts in Aedes aegypti mosquitoes
eLife 12:e83524.
https://doi.org/10.7554/eLife.83524
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