The phoenix hypothesis of speciation.

Area of Science:

• Evolutionary biology
• Population genetics
• Speciation research

Background:

• Allopatric populations accumulate genetic divergence, leading to reproductive isolation.
• Environmental change can accelerate this process but also increases extinction risk.
• Evolutionary rescue involves fixing mutations that enhance adaptation.

Purpose of the Study:

• To explore genetic changes during environmental change using simulations.
• To investigate the role of extinction risk in speciation.
• To test the "phoenix hypothesis of speciation."

Main Methods:

• Simulations using Fisher's geometric model.
• Incorporation of explicit population dynamics.
• Analysis of genetic divergence and reproductive isolation under varying extinction risks.

Main Results:

• Evolutionary rescue fixes large-effect mutations, promoting reproductive isolation.
• The "phoenix hypothesis" predicts greater hybrid breakdown with higher extinction risk.
• Intermediate extinction risk maximized reproductive isolation when limited adaptive mutations were available, due to parallel changes reducing isolation.

Conclusions:

• Speciation rates are influenced by the interplay between environmental change, extinction risk, and the genetic basis of adaptation.
• The "phoenix hypothesis" provides a framework for understanding speciation under environmental stress.
• Optimal speciation occurs at intermediate extinction levels, balancing adaptation and genetic divergence.