Evolution of the additive genetic variance-covariance matrix under continuous directional selection on a complex...

Area of Science:

• Evolutionary biology
• Quantitative genetics
• Animal behavior

Background:

• Human-induced environmental changes necessitate rapid evolutionary adaptation.
• The additive genetic variance-covariance matrix (G) is crucial for predicting adaptive responses to selection.
• Understanding how G evolves under selection is vital but poorly understood.

Purpose of the Study:

• To experimentally investigate changes in the genetic variance-covariance matrix (G) under continuous directional selection.
• To assess the impact of selection on G on the rate of adaptive evolutionary response.

Main Methods:

• Utilized a large dataset (n = 17,328 individuals) from a 31-generation replicated artificial selection experiment in mice.
• Applied the genetic covariance tensor approach to analyze behavioral traits (voluntary wheel running).
• Focused selection on specific running behaviors (days 5 and 6) to observe G matrix evolution.

Main Results:

• Continuous directional selection induced proportional changes across the entire G matrix within four generations.
• These induced changes in G significantly slowed the rate of adaptive response, making it fourfold slower than predicted.
• Selection exacerbated constraints within the G matrix, limiting future adaptive potential.

Conclusions:

• The genetic variance-covariance matrix (G) is not static and evolves under selection.
• Selection can create constraints within G, thereby limiting future adaptive capacity.
• These findings have significant implications for understanding population persistence in the face of rapid environmental change.