The effects of genetic drift and genomic selection on differentiation and local adaptation of the introduced populations of Aedes albopictus in southern Russia

Abstract

Background Asian tiger mosquito Aedes albopictus is an arbovirus vector that has spread from its native habitation areal in Southeast Asia throughout North and South Americas, Europe, and Africa. Ae. albopictus was first detected in the Southern Federal District of the Russian Federation in the subtropical town of Sochi in 2011. In subsequent years, this species has been described in the continental areas with more severe climate and lower winter temperatures. Methods Genomic analysis of pooled Ae. albopictus samples collected in the mosquito populations in the coastal and continental regions of the Krasnodar Krai was conducted to look for the genetic changes associated with the spread and potential cold adaptation in Ae. albopictus. Results The results of the phylogenetic analysis based on mitochondrial genomes corresponded well with the hypothesis that Ae. albopictus haplotype A1a2a1 was introduced into the region from a single source. Population analysis revealed the role of dispersal and genetic drift in the local adaptation of the Asian tiger mosquito. The absence of shared haplotypes between the samples and high fixation indices suggest that gene flow between samples was heavily restricted. Mitochondrial and genomic differentiation together with different distances between dispersal routes, natural and anthropogenic barriers and local effective population size reduction could lead to difficulties in local climatic adaptations due to reduced selection effectiveness. We have found genomic regions with selective sweep patterns which can be considered as having been affected by recent selection events. The genes located in these regions participate in neural protection, lipid conservation, and cuticle formation during diapause. These processes were shown to be important for cold adaptation in the previous transcriptomic and proteomic studies. However, the population history and relatively low coverage obtained in the present article could have negatively affect sweep detection.

Multiple introductions and overwintering shape the progressive invasion of Aedes albopictus beyond the Alps

“…in Southern Russia, but heavily restricted gene flow or population exchange is reported between the different study sites (Konorov et al, 2021). The weak genetic structure, high levels of admixture, and lack of IBD found in this study for Ae.…”

“…In Ae. albopictus , reports of very high levels of differentiation among samples of recently invading populations at regional levels have been identified in Southern Russia, but heavily restricted gene flow or population exchange is reported between the different study sites (Konorov et al, 2021 ). The weak genetic structure, high levels of admixture, and lack of IBD found in this study for A e. albopictus suggest rapid expansion most likely through human‐aided dispersal along transportation routes across the Alps.…”

Human-aided dispersal and population bottlenecks facilitate parasitism escape in the most invasive mosquito species

“…Genetic dynamics of Ae. albopictus populations have been driven by multiple introductions, genetic drifts and founder effects during their invasion process (Gao et al, 2021; Hall et al, 2022; Konorov et al, 2021; Latreille et al, 2019). The weak gregarine diversity (limited density of gregarines from Otu000002 and Otu000003) in recently introduced populations could then be related to those events since the parasite cannot reproduce outside of its host.…”

Genetic Structure of Aedes (Stegomyia) albopictus Populations in Russia

“…Our conclusions are also supported by the results of the analysis of the genomes of individuals from Sochi and Krasnodar cities (Cfa zone), which showed that despite significant differences in the allele frequency spectrum, Ae. albopictus from Sochi and Krasnodar were closely related, had a common origin and formed a clade related to mosquitoes from Italy and Greece ( 42 ). The lack of genetic structure or isolation by distance were observed in many studies on Ae.…”