Interrogation of alternative splicing events in duplicated genes during evolution

Area of Science:

• Evolutionary biology
• Genomics
• Molecular biology

Background:

• Gene duplication generates novel gene functions, while alternative splicing increases proteomic complexity without expanding the genome.
• Both processes are crucial for eukaryotic diversity, but their interplay was previously misunderstood.

Purpose of the Study:

• To investigate the relationship between alternative splicing and gene duplication over evolutionary time.
• To determine how gene family size influences the co-evolution of duplication and alternative splicing.

Main Methods:

• Analysis of alternative splicing occurrence in relation to gene duplication events across different evolutionary timescales.
• Comparison of gene families of varying sizes (2-7 vs. >=8 paralogs) and singleton genes.

Main Results:

• A positive correlation between gene duplication and alternative splicing emerges with ancient duplications, contrary to initial inverse correlations seen in recent duplications.
• Small to medium gene families (2-7 paralogs) show increased alternative splicing and isoform diversity over time.
• Large gene families (>=8 paralogs) exhibit lower alternative splicing rates and fewer isoforms, regardless of duplication age.
• Duplicated genes with alternative splicing are under stronger evolutionary constraint and enriched for molecular transducer activities.

Conclusions:

• Gene duplication and alternative splicing exhibit distinct functional roles and evolutionary constraints depending on their co-occurrence and gene family size.
• These findings suggest a nuanced, synergistic role for gene duplication and alternative splicing in driving evolutionary diversification and speciation.