Evolutionary feedbacks for Drosophila aggression revealed through experimental evolution

Area of Science:

• Evolutionary biology
• Behavioral genetics
• Quantitative genetics
• Ecological genetics

Background:

• Evolutionary feedbacks occur when evolutionary changes in one generation modify the environment for subsequent generations.
• Indirect genetic effects (IGEs) are a key mechanism driving evolutionary feedbacks, but experimental evidence is limited.
• Understanding evolutionary feedbacks is crucial for predicting responses to environmental change, including climate change and agricultural practices.

Purpose of the Study:

• To experimentally investigate the impact of evolutionary feedbacks on the rate and pattern of behavioral evolution.
• To quantify the influence of different types of social feedbacks (positive, negative, none) on the evolution of aggression.
• To determine if social dynamics evolve under different feedback conditions.

Main Methods:

• Experimental evolution using fruit fly (Drosophila melanogaster) populations.
• Manipulation of the social environment to allow or limit evolutionary feedbacks during selection for male-male aggression.
• Comparison of evolutionary trajectories across populations experiencing positive, negative, or no feedbacks, plus unselected controls.

Main Results:

• Populations with negative feedbacks exhibited the slowest evolutionary increase in aggression.
• Populations with positive feedbacks evolved significantly higher levels of aggression ('supernormal' aggression).
• Evolution of underlying social dynamics was observed exclusively in the negative feedback treatment.

Conclusions:

• Indirect genetic effects-mediated evolutionary feedbacks significantly alter the pace and direction of behavioral evolution.
• The type of feedback (positive vs. negative) critically influences the magnitude of evolutionary change.
• Experimental manipulation of feedbacks provides a powerful tool for dissecting the mechanisms of evolutionary change.