When does gene flow facilitate evolutionary rescue?

Area of Science:

• Ecology and Evolutionary Biology
• Population Genetics
• Mathematical Biology

Background:

• Gene flow's impact on evolutionary rescue in structured habitats is a key area of study.
• Theoretical models and experiments suggest intermediate migration rates can maximize rescue probability in deteriorating environments.
• The role of gene flow in facilitating adaptation contrasts with traditional views of it hindering local adaptation.

Purpose of the Study:

• To identify conditions under which gene flow facilitates evolutionary rescue.
• To resolve the apparent conflict between gene flow aiding survival and hindering local adaptation.
• To develop a tractable model for evolutionary rescue in a two-deme system with gene flow.

Main Methods:

• Development of a simple, analytically tractable mathematical model.
• Simulation of evolutionary rescue in a two-deme population structure with varying gene flow.
• Investigation of asymmetries in gene flow, carrying capacities, density regulation, and local growth rates.

Main Results:

• A simple condition for when migration facilitates evolutionary rescue has been identified.
• Intermediate migration rates were shown to be crucial for maximizing rescue probability.
• Asymmetries in gene flow and carrying capacities, along with density regulation, influence rescue outcomes.

Conclusions:

• Gene flow can be a critical factor promoting the survival of populations facing environmental change.
• Understanding the conditions that enable gene flow to facilitate evolutionary rescue is essential for conservation biology.
• The study provides a theoretical framework for predicting population persistence under environmental stress.