Phylogenomics revealed migration routes and adaptive radiation timing of Holarctic malaria vectors of the Maculipennis group

Abstract

Background: Understanding the evolutionary relationships between closely related taxa is important for mosquitoes that transmit human diseases. Six out of 41 dominant malaria vectors in the world belong to the Maculipennis group, which is subdivided into two North American subgroups (Freeborni and Quadrimaculatus), and one Eurasian (Maculipennis) subgroup. Although previous studies considered the Nearctic subgroups as ancestral, details about their relationship with the Palearctic subgroup, and their migration times and routes from North America to Eurasia remain controversial. The Eurasian species An. beklemishevi is currently included in the North American Quadrimaculatus subgroup adding to the uncertainties in mosquito systematics. Results: To reconstruct historic relationships between the North American and Eurasian mosquitoes, we conducted a phylogenomic analysis of 11 Palearctic and 2 Nearctic species based on 1271 orthologous genes using their transcriptomic or genomic sequences. The analysis indicated that the Palearctic species An. beklemishevi clusters together with other Eurasian species and represents a basal lineage among them. Also, An. beklemishevi is related more closely to An. freeborni, which inhabits the Western United States, rather than to An. quadrimaculatus, a species from the Eastern United States. The time-calibrated tree suggests a migration of mosquitoes in the Maculipennis group from North America to Eurasia about 20-25 million years ago through the Bering Land Bridge. A Hybridcheck analysis demonstrated highly significant signatures of introgression events between allopatric species An. labranchiae and An. beklemishevi. The analysis also identified ancestral introgression events between An. sacharovi and its Nearctic relative An. freeborni despite their current geographic isolation. Conclusions: Our phylogenomic analyses reveal migration routes and adaptive radiation timing of Holarctic malaria vectors and strongly support inclusion of An. beklemishevi into the Maculipennis subgroup. The vectorial capacity and the ability to diapause during winter evolved multiple times in Maculipennis evolution. Detailed knowledge of the evolutionary history in the Maculipennis subgroup will help us better understand the current and future patterns of malaria transmission in Eurasia.

Patterns of genetic differentiation imply distinct phylogeographic history of the mosquito species Anopheles messeae and Anopheles daciae in Eurasia

“…messeae and An. daciae occurred ~2 Mya (Yurchenko et al, 2022) and thus overlapped with the glaciation period in Eurasia (Torsvik & Cocks, 2017). Thus, we hypothesize that the glaciation event can potentially result in a long period of disruption of an original population of the ancestral species into different southern refugia whereas one population of mosquitoes was isolated in the Asian location and another in the European location.…”

Patterns of genetic differentiation imply distinct evolutionary histories of the sibling mosquito speciesAnopheles messeaeandAnopheles daciaein Eurasia

“…messeae and An. daciae occurred ~2 Mya (Yurchenko et al 2022) and overlapped with the glaciation period (Torsvik & Cocks, 2017). The glaciation event can result in a long period of disruption of an original population of the ancestral species into different southern refugia whereas one population of mosquitoes was isolated in the Asian location and another in the European location.…”