Population genomics of parallel evolution in gene expression and gene sequence during ecological adaptation

Area of Science:

• Evolutionary Biology
• Population Genomics
• Molecular Ecology

Background:

• Natural selection frequently drives parallel phenotypic evolution in response to similar environmental pressures.
• The genetic and molecular underpinnings of parallel phenotypic traits, including gene expression and genomic divergence, are not fully understood.
• Investigating the relationship between parallel molecular changes and phenotypic divergence is crucial for understanding adaptation.

Purpose of the Study:

• To investigate the extent of parallel gene expression differences and genomic divergence in parallel phenotypic adaptation.
• To determine if gene expression and genomic sequence changes are coupled or decoupled during adaptation.
• To explore the role of divergent selection in parallel molecular differentiation.

Main Methods:

• Population genomic study of parallel ecological adaptation in replicate ecotype pairs of the rough periwinkle (Littorina saxatilis).
• Analysis of gene expression differences and genomic sequence divergence across ecotypes.
• Assessment of repeatability and uniqueness of genomic changes underlying phenotypic divergence.

Main Results:

• Genomic changes underlying parallel phenotypic divergence exhibited both repeatable and unique patterns across ecotype pairs.
• Parallel changes in gene expression or sequence were observed in a limited subset of genes.
• Most divergent genes showed divergence in either gene expression or coding sequence, but rarely both simultaneously.

Conclusions:

• Divergent selection played a significant role in driving parallel molecular differentiation among ecotype pairs.
• Changes in gene expression and gene sequence underlying phenotypic divergence appear to be largely decoupled processes.
• The study provides insights into the complex molecular mechanisms of parallel adaptation.