On the feasibility of saltational evolution

Area of Science:

• Evolutionary biology
• Population genetics
• Mathematical modeling

Background:

• Evolution is often viewed as a gradual process driven by single mutations.
• The potential for simultaneous multiple mutations (multimutation leaps) and their evolutionary significance remains less understood.

Purpose of the Study:

• To investigate the probability and impact of multimutation leaps in an evolutionary process.
• To determine the conditions under which multimutation leaps become a significant evolutionary factor.

Main Methods:

• Developed a mathematical model of evolution on a fitness landscape.
• Derived analytic solutions for the probability of multimutation leaps and their fixation.
• Analyzed the influence of population size, mutation rate, and selection coefficients.

Main Results:

• Under typical evolutionary parameters, the probability of multimutation leaps is low, with minor contributions.
• Sign epistasis can increase the importance of multimutation leaps, especially with elevated mutation rates.
• Stress-induced mutagenesis in microbes may facilitate significant leaps.

Conclusions:

• Multimutation leaps are generally a minor factor in evolution but can be important under specific conditions.
• Elevated mutation rates, like those in stress-induced mutagenesis, can promote leaps.
• Hypothesize that stress-induced mutagenesis is an evolvable adaptive strategy.