Evolution is more repeatable in the introduction than range expansion phase of colonization

Area of Science:

• Evolutionary Biology
• Genomics
• Ecology

Background:

• Understanding the repeatability of evolution is crucial for predicting how populations adapt to new environments.
• Colonization events provide natural experiments to study adaptive evolution and its constraints.

Purpose of the Study:

• To investigate the repeatability of evolution at genomic and phenotypic levels during colonization.
• To assess how different phases of colonization (introduction, establishment, spread) influence evolutionary repeatability.
• To examine the impact of range expansion on the efficiency of natural selection.

Main Methods:

• Utilized replicated microcosm experiments with the red flour beetle (Tribolium castaneum) over 8 generations.
• Analyzed patterns of shared allele frequency changes across populations and experimental replicates.
• Studied allele frequency shifts at conserved genetic loci to infer selection efficiency.

Main Results:

• Adaptive evolution showed higher repeatability during the introduction and establishment phases of colonization.
• The spread phase of colonization exhibited lower evolutionary repeatability.
• Evidence was found supporting the theory that range expansion diminishes the efficiency of selection in purging deleterious alleles.

Conclusions:

• Evolutionary adaptation during colonization can be highly repeatable, particularly in initial stages.
• Stochastic factors continue to play a significant role in shaping evolutionary trajectories.
• Range expansion presents unique challenges to adaptive potential and efficient selection.