Density-Dependent Selection during Range Expansion Affects Expansion Load in Life History Traits

Area of Science:

• Evolutionary Biology
• Ecology
• Population Genetics

Background:

• Range expansion models often study life history evolution or allele surfing separately.
• Interactions between life history trait evolution and allele surfing during spatial spread are not well understood.

Purpose of the Study:

• To investigate the combined effects of density-dependent selection and allele surfing on life history trait evolution during range expansion.
• To assess how ecological factors influence genetic drift and fitness consequences at the expanding range edge.

Main Methods:

• Utilized spatially explicit simulations to model a complex range expansion scenario.
• Incorporated density-dependent selection and allele surfing dynamics.
• Analyzed genetic and fitness outcomes across different life history traits.

Main Results:

• Density-dependent selection's effect on allele surfing varies by life history trait, either diminishing or enhancing it.
• Selection is weaker on competitive ability (K-selected traits) than on birth rate (r-selected traits) at the range edge.
• Deleterious mutation frequency correlates with selection efficacy and mutation accumulation, influenced by life history traits.
• Fitness consequences of allele surfing depend on the population density during expansion.

Conclusions:

• Density-dependent selection and allele surfing have complex, interacting effects on life history evolution during range expansion.
• The efficacy of selection and mutation accumulation are linked to specific life history traits and genetic drift.
• Understanding the interplay between ecology and genetic load is crucial for interpreting studies on range expansion.