Evolution of a Fluctuating Population in a Randomly Switching Environment.

Area of Science:

• Evolutionary dynamics
• Population genetics
• Environmental stochasticity

Background:

• Environmental conditions fundamentally shape population evolution and resource competition.
• Finite populations with competing strains are subject to both external (environmental) and internal (demographic) noise.

Purpose of the Study:

• To investigate the impact of coupled environmental and demographic noise on the fixation properties and population size distribution of two competing strains.
• To analyze scenarios of pure resource competition and public good provision.
• To understand how environmental switching rates influence evolutionary outcomes.

Main Methods:

• Analytical modeling of population dynamics.
• Computer simulations of competing strains in a fluctuating environment.
• Analysis of fixation probabilities and population size distributions.

Main Results:

• Coupled environmental and demographic noise significantly increases the fixation probability of the slower-growing species.
• Population size distribution can exhibit unimodal, bimodal, or multimodal patterns.
• Noise-induced transitions in population size distribution occur when environmental switching rates align with population growth rates.

Conclusions:

• Environmental and demographic noise are critical factors in evolutionary processes, capable of altering competitive exclusion.
• The interplay of noise and environmental dynamics can lead to complex population structures and unexpected evolutionary trajectories.
• Understanding these noise-driven phenomena is essential for predicting population persistence and evolution in variable environments.