Fission as a source of variation for group selection

Area of Science:

• Evolutionary biology
• Theoretical ecology
• Population genetics

Background:

• Heritable variation is essential for natural selection to drive evolutionary change.
• Group selection models typically rely on within-group stochastic processes for inter-group variation.
• Existing models often assume asexual reproduction (cloning) during group reproduction events.

Purpose of the Study:

• To investigate fission as a significant, underappreciated source of variation in group selection.
• To model the impact of fission on the generation of variation among groups.
• To assess how fission influences the efficacy of group selection.

Main Methods:

• Construction of a mathematical model for the fission process.
• Inclusion of a parameter to quantify variation generated during fission.
• Illustrative examples to demonstrate the model's predictions.

Main Results:

• Fission can introduce substantial variation between groups, unlike models where groups simply clone themselves.
• A parameter controlling variation during fission directly impacts the model's outcomes.
• Fission can be a more biologically realistic mode of group reproduction.

Conclusions:

• Fission represents a key mechanism for generating inter-group variation, crucial for group selection.
• Incorporating fission into models can significantly enhance the power of group selection.
• This study highlights the importance of group-level reproduction mechanisms in evolutionary dynamics.