Scaling expectations for the time to establishment of complex adaptations

Area of Science:

• Evolutionary biology
• Population genetics
• Molecular evolution

Background:

• Most evolutionary biology research focuses on adaptation.
• A comprehensive theory for acquiring complex adaptations via population genetics is lacking.
• Novel traits often require multiple mutations for a fitness advantage.

Purpose of the Study:

• To develop a general theory for the population-genetic mechanisms of complex adaptation acquisition.
• To explore how rates of acquiring specific adaptations scale with population size.
• To provide insights into ongoing debates on the molecular basis of adaptation.

Main Methods:

• Analysis of evolutionary forces: mutation, recombination, and random genetic drift.
• Examination of joint constraints on these evolutionary forces.
• Scaling analysis of adaptation acquisition rates with population size.

Main Results:

• Identified the roles of mutation, recombination, and genetic drift in acquiring complex adaptations.
• Demonstrated how adaptation rates scale with population size based on these forces.
• Offered insights into the adaptive utility of recombination and the role of drift in traversing adaptive valleys.

Conclusions:

• Population size significantly influences the rate of complex adaptation acquisition.
• Understanding the interplay of mutation, recombination, and drift is crucial for a general theory of adaptation.
• This framework addresses key controversies in molecular evolution and adaptation.