Variability in life-history switch points across and within populations explained by Adaptive Dynamics

Area of Science:

• Evolutionary Ecology
• Theoretical Biology
• Population Dynamics

Background:

• Life-history switch points (SPs) like hatching, metamorphosis, and maturation are crucial for understanding evolutionary ecology.
• Previous fitness optimization studies explain SP timing variation across populations and environments but not within populations.
• Optimization theory often predicts a single optimal SP, failing to account for individual variability within a population.

Purpose of the Study:

• To re-examine the evolution of a single life-history switch point (SP) between juvenile and adult stages.
• To utilize an Adaptive Dynamics (AD) perspective, integrating population dynamics with life-history strategy evolution.
• To explain within-population variability in SP timing.

Main Methods:

• Employed an Adaptive Dynamics (AD) model to simulate the evolution of a single life-history switch point.
• Considered the feedback loop between population dynamics and the evolution of life-history strategies.
• Analyzed diverse evolutionary scenarios based on demographic and environmental conditions.

Main Results:

• The AD model demonstrated various evolutionary outcomes, including loss of the juvenile stage and single optimal SPs.
• Identified alternative optimal SPs contingent on initial phenotypes.
• Revealed sympatric coexistence of two SP phenotypes driven by disruptive selection, explaining within-population variability.

Conclusions:

• Adaptive Dynamics (AD) successfully predicts life-history SP variability across environments and populations, aligning with optimization approaches.
• Crucially, AD explains within-population SP variability through sympatric disruptive selection.
• The model serves as a theoretical tool for understanding life-history variability, particularly within species in shared environments.