Probability of fixation in a heterogeneous environment

Area of Science:

• Evolutionary Biology
• Population Genetics
• Theoretical Ecology

Background:

• Understanding mutation fixation probability is crucial for evolutionary dynamics.
• Metapopulations in heterogeneous selective environments present complex evolutionary challenges.
• Existing approximations for fixation probability may not cover all ecological scenarios.

Purpose of the Study:

• To investigate the probability of fixation for new mutations in heterogeneous metapopulations.
• To evaluate the accuracy of existing and novel approximations for fixation probability.
• To explore the impact of population structure and migration rates on fixation probabilities.

Main Methods:

• Computational simulations were employed to model metapopulation dynamics.
• Several analytical approximations, including a novel separation-of-timescales approach, were tested.
• The study considered multideme metapopulations with varying population structures and migration rates.

Main Results:

• No single approximation accurately predicted fixation probabilities across all tested conditions.
• Established approximations performed well at low and high migration limits.
• A new separation-of-timescales approximation showed accuracy for intermediate migration rates with moderate selection.
• Heterogeneous selection, surprisingly, often increased allele fixation probability compared to homogeneous environments.

Conclusions:

• Approximations for fixation probability are sensitive to migration rates and selection intensity.
• The separation-of-timescales approach offers improved predictions for intermediate migration scenarios.
• Metapopulation heterogeneity can be a significant factor, potentially promoting fixation of new alleles.