Evolutionary double suicide in symbiotic systems

Area of Science:

• Evolutionary biology
• Ecology
• Theoretical biology

Background:

• Mutualisms, symbiotic relationships benefiting both species, are vulnerable to coextinction cascades where the loss of one partner drives the other to extinction.
• While the consequences of partner loss are recognized, the evolutionary mechanisms triggering extinction in mutualisms remain underexplored.

Discussion:

• This study theoretically examines the coevolution of host exploitation and dependence in mutualisms to understand extinction triggers.
• The model investigates whether evolutionary adaptation to partner loss can prevent collateral extinctions within symbiotic partnerships.

Key Insights:

• Mutualisms exhibit higher vulnerability to coextinction via adaptive evolution, termed "evolutionary double suicide," compared to parasitic relationships.
• The evolutionary pressure from partner loss seldom drives a reversion to a non-symbiotic, autonomous state in the studied mutualistic systems.

Outlook:

• These findings offer a novel perspective on the inherent evolutionary fragility of mutualistic interactions.
• The research highlights the rarity of evolutionary transitions from mutualism to parasitism, challenging previous assumptions.