The effect of selection environment on the probability of parallel evolution

Area of Science:

• Evolutionary biology
• Microbial evolution
• Genetics

Background:

• Parallel and convergent evolution demonstrate similar evolutionary changes in independent populations.
• Parallel evolution suggests adaptation under genetic constraints, but driving factors require experimental validation.

Purpose of the Study:

• To experimentally quantify parallel evolution in Pseudomonas fluorescens across diverse environments.
• To investigate the impact of selection environment, adaptation level, and environmental heterogeneity on gene-level parallel evolution.

Main Methods:

• Evolving 15 replicate Pseudomonas fluorescens populations in five distinct environments.
• Analyzing changes at phenotypic, gene, and nucleotide levels.
• Testing correlations between environmental factors and the degree of parallel evolution.

Main Results:

• Parallel evolution was more frequent in populations from identical environments, but varied significantly.
• Adaptation level did not predict parallelism; available beneficial mutations correlated negatively.
• Spatially structured, multi-resource environments showed significantly higher parallel evolution.

Conclusions:

• Environmental heterogeneity is a key factor influencing the predictability of parallel evolution.
• Results highlight the critical role of the environment in shaping evolutionary trajectories.
• Further research can explore conditions that make evolutionary outcomes predictable.