Kin selection and natal dispersal in an age-structured population

Area of Science:

• Evolutionary Biology
• Behavioral Ecology

Background:

• Iteroparity, the ability to reproduce multiple times, can influence life-history traits.
• Habitat fragmentation presents unique challenges for species survival and dispersal.
• Kin selection models are crucial for understanding the evolution of social behaviors like dispersal.

Purpose of the Study:

• To investigate how iteroparity affects the evolution of dispersal strategies in fragmented habitats.
• To explore the role of maternal age and demographic stochasticity in shaping age-specific dispersal rates.
• To analyze the interplay of kin competition and local competition on dispersal evolution.

Main Methods:

• Utilized a kin selection model incorporating demographic stochasticity.
• Examined age-specific genetic identities and local age structure.
• Compared scenarios with age-independent and age-dependent juvenile dispersal rates.

Main Results:

• Unconditional evolutionarily stable dispersal rate increases with adult survival when maternal age is not considered.
• Age-specific dispersal is driven by two opposing forces: reduced local competition for older mothers and increased kin competition for their offspring.
• The balance between these forces depends on the variance in age structure across subpopulations.

Conclusions:

• Iteroparity significantly shapes dispersal evolution in fragmented environments.
• Maternal age is a key factor influencing age-specific dispersal, creating opposing selective pressures.
• The variance in sub-population age structure determines the net evolutionary outcome of dispersal strategies.