Rates of evolution differ between cell types identified by single-cell RNAseq in threespine stickleback

Area of Science:

• Evolutionary genomics
• Cell biology
• Population genetics

Background:

• Evolutionary rates vary significantly across genes.
• Some gene categories are highly conserved, while others show rapid divergence due to selection.
• Understanding cell-type-specific evolutionary dynamics is crucial.

Purpose of the Study:

• To investigate whether distinct cell types exhibit differential rates of evolutionary divergence.
• To explore the relationship between cell type identity and the evolution of characteristic genes.
• To integrate single-cell RNA sequencing with population genomic data.

Main Methods:

• Utilized single-cell RNA sequencing (scRNAseq) data.
• Integrated scRNAseq with population genomic data (F_ST and dN/dS ratios).
• Analyzed allele frequency divergence and interspecies divergence for cell-type-specific genes.

Main Results:

• Cell types demonstrate varying evolutionary rates in their characteristic genes.
• Neutrophils, B cells, and fibroblasts showed elevated F_ST at characteristic genes.
• Immune cell-associated genes exhibited significantly faster evolution compared to non-immune genes.

Conclusions:

• Genes defining immune cell types evolve more rapidly.
• The integration of scRNAseq and evolutionary genomics provides novel insights into cell type evolution.
• Cellular identity is linked to distinct evolutionary trajectories.