The genome-wide signature of short-term temporal selection

Area of Science:

• Evolutionary Biology
• Population Genomics

Background:

• Natural selection is a key evolutionary driver, but genome-wide, multigenerational studies in natural populations are scarce.
• Understanding selection patterns is crucial for interpreting genetic variation and divergence.

Purpose of the Study:

• To investigate genome-wide selection patterns over a decade in the microcrustacean Daphnia pulex.
• To assess the role of fluctuating selection in shaping nucleotide diversity.

Main Methods:

• Conducted a 10-year population-genomic survey.
• Sequenced the genomes of approximately 800 Daphnia pulex isolates.

Main Results:

• Observed pervasive near quasi-neutrality with significant temporal variance in selection coefficients.
• Identified a prevalence of weak positive selection on minor alleles.
• Found numerous small linkage islands of selection influencing nucleotide diversity genome-wide.

Conclusions:

• Interannual fluctuating selection significantly determines standing genetic variation in natural populations.
• Results challenge conventional interpretations of nucleotide diversity and divergence patterns.
• Highlights the need for advanced theoretical models for population genomic data interpretation.