Olivero, J. | bioRxiv Science

bioRxiv2023

Potential climate change effects on the distribution of urban and sylvatic dengue and yellow fever vectors

Climate change may increase the risk of dengue and yellow fever transmission by urban and sylvatic mosquito vectors. Previous research primarily focused on Aedes aegypti and Aedes albopictus. However, these diseases involve a complex transmission cycle in which sylvatic vectors are also involved. Our aim was to analyse which mosquito species could contribute to the increased risk of transmission of these diseases due to climate change, and to identify where the risk increase could most likely occur. Using a biogeographical approach, we mapped areas where mosquito favourability could increase, decrease or remain stable in the near (2041-2060) and distant (2061-2080) future. Models predict dengue vectors expanding in West and Central Africa and in South-East Asia, reaching Borneo. Yellow fever vectors could spread in West and Central Africa and in the Amazon. In Europe, the models suggest a re-establishment of Ae. aegypti, while Ae. albopictus will continue to find new favourable areas. The results underline the need to focus more on vectors Ae. vittatus, Ae. luteocephalus and Ae. africanus in West and Central sub-Saharan Africa, especially Cameroon, Central Africa Republic, and northern Democratic Republic of Congo; and suggest the need for a protocol to prevent dengue and yellow fever that include surveillance of neglected sylvatic vectors.

ecology↗

bioRxiv2021

Population inter-connectivity over the past 120,000 years explains distribution and diversity of Central African hunter-gatherers

The evolutionary history of African hunter-gatherers holds key insights into modern human diversity. Here we combine ethnographic and genetic data on Central African hunter-gatherers (CAHG) to show that their current distribution and density is explained by ecology rather than by a displacement to marginal habitats due to recent farming expansions, as commonly assumed. We also predict hunter-gatherer presence across Central Africa over the past 120,000 years using paleoclimatic reconstructions, which were statistically validated by dated archaeological sites. Finally, we show that genomic estimates of separation times between CAHG groups match our ecological estimates of periods favouring population splits, and that recoveries of connectivity would have facilitated subsequent gene-flow. Our results reveal that CAHG stem from a deep history of partially connected populations. This form of sociality allowed the coexistence of relatively large effective population sizes and local differentiation, with important implications for the evolution of genetic and cultural diversity in Homo sapiens.

evolutionary biology↗