In the recent past, human impacts on the environment have been some of the strongest forces shaping genetic variation in other species. Adaptation of species to human habitats, such as urban environments, is particularly interesting in systems where arthropods are disease vectors and where humans are also the major food source of the arthropods. The proposed work will explore the role of humans in shaping variation in the vector mosquito species Aedes aegypti both neutrally through human-mediated dispersal, and as a selective force through the creation of novel environments with dependable breeding sites and hosts. Early evidence suggests populations of human-adapted mosquitoes breeding in urban centers have arisen from multiple independent domestication events of animal-eating, forest-dwelling populations of A. aegypti. The PIs will examine DNA sequences from worldwide field collections of A. aegypti to 1) determine ancestry in the species and infer whether domestication has occurred multiple times, and 2) explore patterns of variation in a gene potentially linked to human host choice and a close ecological linkage with humans.
This research will help elucidate patterns of domestication relevant to many organisms in increasingly human-dominated landscapes. Overlap of mosquito and human populations has strong implications for disease transmission, as A. aegypti is the principal vector of yellow fever and dengue viruses. All data and samples will be publicly available through the database PopGenBase (integrated with Google Earth) and the Peabody Museum at Yale. This project will provide training for young international scientists, U.S. undergraduates, and K-12 biology teachers and students from local public schools.
In the recent past, human impacts on the environment have been some of the strongest forces shaping genetic variation in other species. Though human impacts are most often considered harmful to species, human modifications to the landscape can actually create new environments (e.g. cities) to which other species can adapt, bringing them into close contact with humans. These "domestication" processes are especially important in the case of arthropod vectors of disease (e.g. mosquitoes), where overlap of vector and human populations can lead to epidemic disease spread. We performed a global genetic study of one such species, the dengue and yellow fever mosquito, Aedes aegypti, whose history and current distribution has been profoundly shaped by humans. Results from DNA sequences of four genes support the hypothesis that Ae. aegypti originated in Africa, where a domestic form arose and spread throughout the tropical and subtropical world with human trade and movements. Our evidence suggests that human trade routes first moved domestic Ae. aegypti out of Africa into the New World, followed by a later invasion in Southeast Asia and the Pacific. This research helps elucidate patterns of domestication relevant to many organisms in increasingly human-dominated landscapes. Additionally, understanding the evolution of human adaption in mosquitoes is important from a public health perspective, as overlap of mosquito and human populations has strong implications for disease transmission. All genetic data from this study will be publicly available through GenBank upon manuscript publication, and mosquito collections/DNA samples are available to research institutions upon request. This project provided training for young international scientists, U.S. undergraduates from groups underrepresented in the sciences, and K-12 biology teachers and students from local public schools.
