The effect of scale dependent processes on kin selection: mating and density regulation

Area of Science:

• Evolutionary Biology
• Behavioral Ecology
• Population Genetics

Background:

• Kin selection theory explains fitness interactions within trait groups, involving both inter- and intra-group selection components.
• Existing models often assume dispersal and density regulation operate at the same spatial scale as trait groups, limiting applicability.
• Intergroup selection's importance hinges on inter-group fertility differences and genetic variation among groups.

Purpose of the Study:

• To develop a more general kin selection model accommodating distinct spatial scales for interaction, density regulation, and dispersal.
• To explore how spatial scales of ecological processes influence the evolution of altruism and genetic variation.
• To re-evaluate the scale of population regulation's impact on intergroup selection.

Main Methods:

• A novel mathematical model is presented that decouples spatial scales of interaction, density regulation, and dispersal.
• The model framework allows existing models' results to be recovered as special cases.
• A specific mating/migration model is analyzed to determine how biological parameters influence variation components.

Main Results:

• The appropriate scale for studying kin selection is determined by the spatial scale of population regulation.
• Only a fraction of total inter-trait group variance is accessible to intergroup selection.
• Genetic variation generated at scales larger than the regulation scale does not support altruism evolution.

Conclusions:

• Decoupling spatial scales in kin selection models provides a more comprehensive framework.
• Population regulation scale is a critical factor in determining the efficacy of intergroup selection.
• Understanding spatial scales of ecological processes is crucial for studying relatedness and altruism in natural populations.