Temporal variability can promote migration between habitats

Area of Science:

• Ecology and Evolution
• Population Dynamics
• Environmental Science

Background:

• Migration is crucial for species survival and adaptation.
• Fixed environments with a single best site typically disfavor migration.
• The role of environmental variability in favoring migration remains incompletely understood.

Purpose of the Study:

• To determine if environmental variability can favor migration when a single best site exists on average.
• To provide a general and precise framework for understanding migration's evolutionary benefits under fluctuating conditions.

Main Methods:

• Development of new mathematical inequalities to analyze stochastic growth rates.
• Utilizing simulations to illustrate the theoretical findings.
• Examining the interplay of site differences, migration paths, and environmental fluctuations.

Main Results:

• Stochastic growth rate can increase with migration when fitness fluctuates across sites.
• The effect of migration depends on the difference in expected growth rates and the variance of these differences.
• High environmental variance can lead to beneficial "bursts" of growth in suboptimal sites.

Conclusions:

• Environmental variability, not just average conditions, is a key driver for the evolution of migration.
• The spatial distribution of habitat quality and its temporal fluctuations critically influence migration's importance.
• Findings challenge the reduction principle and offer insights into ecological dynamics and evolutionary biology.