Is biased mutation sufficient to save runaway sexual selection?

Area of Science:

• Evolutionary Biology
• Behavioral Ecology

Background:

• Theoretical models in the 1980s proposed that ornaments and preferences coevolve, leading to exaggerated traits via runaway sexual selection.
• Later models introduced preference costs, challenging the long-term persistence of exaggerated ornaments.
• Biased mutation models, assuming mutations favor smaller ornaments, were thought to resolve this, allowing exaggeration despite costs.

Purpose of the Study:

• To re-evaluate the assumptions of biased mutation models in the context of sexual selection.
• To investigate the role of investment versus efficiency in ornament development under biased mutation.
• To determine the conditions under which exaggerated ornaments and preferences can stably persist.

Main Methods:

• Developed a theoretical model separating investment and efficiency in ornament production.
• Analyzed the impact of biased mutation acting solely on efficiency, not average investment.
• Simulated scenarios to assess the stability of exaggerated ornaments and preferences.

Main Results:

• Exaggerated ornaments and preferences can persist stably if they initially arise.
• The persistence is contingent on strong initial preferences to initiate the runaway process.
• Biased mutation acting only on efficiency does not guarantee the initiation or long-term stability of exaggerated traits without sufficient initial preference strength.

Conclusions:

• The persistence of exaggerated ornaments depends on more than just biased mutation.
• Strong initial preferences are crucial for overcoming preference costs and driving runaway sexual selection.
• Biased mutation alone may be insufficient to maintain extreme sexual trait exaggeration over evolutionary time.