Comparative transcriptomics reveal tissue level specialization towards diet in prickleback fishes

Area of Science:

• Comparative genomics
• Fish biology
• Physiological ecology

Background:

• Dietary adaptations in fish are not fully understood beyond basic traits.
• Investigating digestive and metabolic specializations is crucial for understanding fish evolution and ecology.

Purpose of the Study:

• To compare digestive and metabolic specializations across four closely related prickleback fish species with different diets.
• To identify the roles of the intestine and liver in dietary adaptation through gene expression and isotopic analysis.

Main Methods:

• Compared gut length, liver stable isotope ratios (δ13C and δ15N), and gene expression in intestine and liver tissues.
• Analyzed wild-caught fish and fish fed controlled carnivore or omnivore diets for 4 weeks.
• Utilized comparative genomics and stable isotope analysis to assess dietary adaptation.

Main Results:

• Gut length was significantly longer in the herbivorous Xiphister mucosus.
• Stable isotope signatures confirmed assimilation of laboratory diets.
• The liver exhibited species-specific gene expression patterns, with fewer changes (<40 genes) compared to the intestine, suggesting the liver is central to specialization.

Conclusions:

• The fish intestine demonstrates functional plasticity in response to diet.
• The liver plays a significant role in species-specific dietary specialization, as evidenced by its unique gene expression patterns.
• These findings advance our understanding of the molecular basis of dietary adaptation in fishes.