Suicidal selection: Programmed cell death can evolve in unicellular organisms due solely to kin selection

Area of Science:

• Evolutionary biology
• Theoretical biology
• Origin of life

Background:

• Programmed cell death (PCD) is a cell suicide process observed in unicellular organisms, but its evolutionary origin is unclear.
• While kin selection maintains PCD in existing populations, its role in the origin of PCD is debated.
• Alternative hypotheses for PCD origin include environmental triggers, beneficial mutation hitchhiking, or pathology.

Purpose of the Study:

• To investigate whether kin selection alone is sufficient to explain the origin of PCD in unicellular organisms.
• To compare the evolutionary viability of direct versus indirect benefits to kin in driving PCD.
• To examine the impact of kin recognition accuracy on the evolution of PCD.

Main Methods:

• Utilized an artificial life model to simulate evolutionary dynamics.
• Modeled scenarios with varying degrees of direct and indirect benefits to kin.
• Assessed the influence of kin recognition fidelity on PCD evolution.

Main Results:

• Demonstrated that kin selection is sufficient for the emergence of PCD in unicellular life.
• Found that direct benefits to kin (resource provision) are more potent drivers of PCD than indirect benefits (harming non-kin).
• Showed that direct benefits are viable within a narrower range of kin recognition strictness compared to indirect benefits.

Conclusions:

• Kin selection provides a sufficient mechanism for the evolutionary origin of programmed cell death in unicellular organisms.
• The evolution of PCD is influenced by the type of benefit conferred to kin and the organism's ability to recognize kin.