Genomic Shifts, Phenotypic Clines, and Fitness Costs Associated With Cold Tolerance in the Asian Tiger Mosquito

Abstract

Climatic variation is a key driver of genetic differentiation and phenotypic traits evolution, and local adaptation to temperature is expected in widespread species. We investigated phenotypic and genomic changes in the native range of the Asian tiger mosquito, Aedes albopictus. We first refine the phylogeographic structure based on genome-wide regions (1,901 ddRAD SNPs) from 41 populations. We then explore the patterns of cold adaptation using phenotypic traits measured in common garden (wing size and cold tolerance) and genotype–temperature associations at targeted candidate regions (51,706 exon capture SNPs) from 9 populations. We confirm the existence of three evolutionary lineages including clades A (Malaysia, Thailand, Cambodia, and Laos), B (China and Okinawa), and C (South Korea and Japan). We identified temperature-associated differentiation in fifteen out of 221 candidate regions but none in ddRAD regions, supporting the role of directional selection in detected genes. These include genes involved in lipid metabolism and a circadian clock gene. Most outlier SNPs are differently fixed between clades A and C, while clade B has an intermediate pattern. Females are larger at higher latitude yet produce no more eggs, which might favor the storage of energetic reserves in colder climate. Non-diapausing eggs from temperate populations survive better to cold exposure than those from tropical populations, suggesting they are protected from freezing damages but this cold tolerance has a fitness cost in terms of egg viability. Altogether, our results provide strong evidence for the thermal adaptation of A. albopictus across its wide temperature range.

All that changes is not shift: methodological choices influence niche shift detection in freshwater invasive species

“…As methodological choices can outweigh biological effects, the risk of apparent niche shifts should be carefully considered when planning the analysis, and researchers should pay special attention to testing the robustness of their conclusions. Direct measures of actual niche shifts, such as experimental approaches that approximate the fundamental niche and/or genomic analyses, would be extremely helpful to verify whether observed shifts represent actual evolutionary processes (Kearney and Porter 2009, Sherpa et al 2022).…”

Genetic Diversity of Dengue Vector Aedes albopictus Collected from South Korea, Japan, and Laos

“…Additionally, nondiapausing eggs have improved cold exposure endurance compared with eggs from tropical populations, demonstrating that cold tolerance comes at a fitness cost in terms of egg viability [ 63 ]. Although research on the introduction and spread of disease-controlling vectors is ongoing around the world, Korea has yet to conduct any such studies [ 20 , 39 , 64 ].…”

“…In addition, previous studies have shown that clusters of Ae. albopictus were divided according to temperate and tropical regions of Asia [ 14 , 39 , 80 , 81 ], and the Korean populations had distinct haplotypes while sharing certain haplotypes with other populations from different countries. Therefore, an in-depth study of the origin of Ae.…”

“…albopictus has expanded its distribution areas through human activities in Southeast Asia, which is its place of origin, and is currently found in all parts of the world except Antarctica [ 35 , 36 , 37 ]. The establishment of successful mosquito control programs can be effective when based on proper knowledge of genetic variation and population dynamics [ 38 , 39 ]. So far, to our knowledge, currently there is limited information about the population genetics of Ae.…”

Genomic profiling of climate adaptation in Aedes aegypti along an altitudinal gradient in Nepal indicates nongradual expansion of the disease vector

“…Further investigations of cold tolerance in the native range of Ae. albopictus support thermal adaptation across a temperature cline (Sherpa et al, 2022). D. melanogaster has also been shown to carry beneficial alleles for the survival under temperate and tropical conditions prior to their invasion in North America and Australia (Bergland et al, 2016).…”