Alternative Splicing and Gene Expression Variation Underlie Population and Life History Differences in an Amphibian

Area of Science:

• Evolutionary Biology
• Molecular Biology
• Environmental Science

Background:

• Phenotypic variation is common, but molecular mechanisms are poorly understood.
• Gene expression and alternative splicing are key post-transcriptional processes influencing adaptation and plasticity.
• Wood frogs (Rana sylvatica) offer a model system due to their complex life cycle and adaptation to environmental gradients.

Purpose of the Study:

• To investigate the molecular mechanisms, specifically gene expression and alternative splicing, underlying phenotypic divergence in wood frog populations.
• To assess how road adjacency and pollution influence transcriptomic differences.
• To understand the roles of plasticity versus genetic differentiation in population divergence.

Main Methods:

• Comparative transcriptomic analysis of gene expression and alternative splicing in wood frogs.
• Examining populations across road adjacency and pollution gradients.
• Analyzing differences between hatchlings and adults, and between roadside and woodland populations.

Main Results:

• Thousands of genes showed differential expression and splicing between wood frog life stages (hatchlings vs. adults).
• Transcriptomic profiles (expression and splicing) clustered strongly by population, indicating population-specific responses.
• Two differentially expressed genes (HSP70, Gpsm2) and one differentially spliced gene (Cd82) distinguished roadside from woodland populations.
• Low genetic differentiation suggests transcriptomic differences arise from plasticity.

Conclusions:

• Transcriptomic plasticity, encompassing both gene expression and alternative splicing, is a significant driver of phenotypic variation during development and population differentiation in wood frogs.
• Environmental factors like road proximity and pollution can induce specific transcriptomic changes.
• Plastic responses play a crucial role in adaptation and divergence, even in the face of gene flow.