The phenetic structure of Aedes albopictus

Area of Science:

• Arthropod-borne disease epidemiology
• Evolutionary biology
• Geometric morphometrics

Background:

• The primary Chikungunya virus vector, Aedes albopictus, has undergone recent large-scale migrations globally.
• Understanding microevolutionary changes in new territories is crucial for predicting disease spread.
• Quantitative traits can reveal adaptations, competition, and founder effects.

Purpose of the Study:

• To compare wing size and shape across 22 Aedes albopictus populations worldwide.
• To investigate the influence of environmental factors, geography, and migratory routes on vector populations.
• To detect potential microevolutionary changes in Aedes albopictus.

Main Methods:

• Landmark-based geometric morphometrics applied to 18 wing landmarks from 1572 Ae. albopictus females.
• Inclusion of related species (Ae. riversi, Ae. flavopictus) for interspecific comparison.
• Analysis of wing size and shape variation in relation to climatic data, geography, and known expansion routes.

Main Results:

• Aedes albopictus, Ae. riversi, and Ae. flavopictus showed similar wing size but distinct shapes.
• Wing size variation correlated with climatic data, while shape variation was linked to geography and expansion history.
• Two main wing shape clusters identified: Southeast Asian populations and a second group including Japan, Florida, Hawaii, and Reunion Island.
• US and Japanese populations shared similar wing shapes, suggesting a common recent ancestor.
• Populations from areas with recent Chikungunya epidemics (Reunion Island, Thailand) did not cluster together.

Conclusions:

• Wing size is influenced by climate, whereas wing shape reflects geographic differences and migratory patterns.
• Observed shape variations align with genetic drift, indicating microevolutionary changes during Ae. albopictus expansion.
• Migratory routes, rather than solely environmental factors, appear to shape vector populations in new territories.