Microevolutionary change in wild stickleback: Using integrative time-series data to infer responses to selection

Area of Science:

• Evolutionary Biology
• Population Genetics
• Ecology

Background:

• Understanding evolutionary processes driving trait change in wild populations is a central goal.
• Quantifying evolutionary change requires linking trait variation to allele frequency shifts at causal loci.
• Existing theoretical models often fail to capture the complex dynamics of natural populations.

Purpose of the Study:

• To investigate how different modes of selection (directional, episodic, balancing) influence microevolutionary change in correlated traits.
• To link observed trait changes to shifts in genetic architecture, including allele frequencies and genomic breeding values.
• To provide a detailed description of microevolutionary processes shaping trait evolution in a natural population.

Main Methods:

• Utilized a decade-long, integrative phenome-to-genome time-series dataset.
• Analyzed wild threespine stickleback (Gasterosteus aculeatus) populations.
• Quantified changes in allele frequencies and genetic architecture of feeding and swimming traits.

Main Results:

• Feeding traits exhibited significant changes (up to 25% over 10 generations) driven by alterations in genetic architecture.
• Allele frequencies at feeding trait loci showed changes exceeding expectations under genetic drift, indicating directional selection.
• Swimming trait loci displayed allele frequency dynamics consistent with fluctuating selection, correlated with population crashes.

Conclusions:

• Microevolutionary change in wild populations involves simultaneous action of diverse selection modes on different traits.
• Observed trait evolution is underpinned by dynamic shifts in genetic architecture and allele frequencies.
• This study offers a comprehensive analysis of microevolutionary processes and their impact on correlated trait evolution in a natural setting.