Genome Structural Variants Shape Adaptive Success of an Invasive Urban Malaria Vector Anopheles stephensi.

Area of Science:

• Genomics
• Evolutionary Biology
• Medical Entomology

Background:

• Global change facilitates invasive species spread, but genetic underpinnings of adaptation are unclear.
• Anopheles stephensi is a significant urban malaria vector in South Asia and an invasive species in islands and Africa.

Purpose of the Study:

• Investigate the role of genome structural variants (SVs) in the adaptation of invasive Anopheles stephensi.
• Identify genetic adaptations enabling Anopheles stephensi's success in new environments.

Main Methods:

• Whole genome sequencing of 115 Anopheles stephensi mosquitoes from invasive island populations and mainland India.
• Identification and frequency analysis of structural variants (duplications and deletions).
• Analysis of genomic regions with signatures of selective sweeps and candidate adaptive variants.

Main Results:

• Discovered 2,988 duplications and 16,038 deletions in Anopheles stephensi populations.
• Identified three novel candidate duplication mutations linked to insecticide resistance.
• Found candidate SVs associated with larval tolerance to brackish water.
• Observed that most high-frequency SVs in island populations originated from the mainland.

Conclusions:

• Structural variants play a crucial role in the adaptive evolution and invasive success of Anopheles stephensi.
• SV-driven adaptations, including insecticide resistance and brackish water tolerance, facilitate the spread of this malaria vector.
• Existing genetic variation from ancestral populations significantly contributes to the success of invasive Anopheles stephensi populations.