Rapid Dietary Shift in Podarcis siculus Resulted in Localized Changes in Gut Function.

Area of Science:

• Ecology and Evolutionary Biology
• Comparative Physiology
• Animal Nutrition

Background:

• Dietary shifts drive evolutionary adaptations in gut physiology.
• The Podarcis siculus lizard populations on Croatian islands exhibit distinct dietary niches.

Purpose of the Study:

• To investigate the nutritional physiology of Podarcis siculus populations adapting to omnivorous diets.
• To compare gut structure, digestive enzymes, microbial fermentation, and plant digestibility between omnivorous and insectivorous lizard populations.

Main Methods:

• Comparative analysis of gut morphology and enzyme activities (amylase, trehalase) between island and mainland lizard populations.
• Measurement of hindgut microbial fermentation products (short-chain fatty acids).
• Laboratory assessment of plant material digestibility in lizards fed experimental diets.

Main Results:

• Omnivorous Pod Mrčaru lizards showed heavier guts but similar gut structure compared to insectivorous populations.
• Enzymatic differences were primarily observed between island and mainland populations, with Pod Mrčaru lizards exhibiting higher hindgut amylase and trehalase.
• Pod Mrčaru lizards demonstrated enhanced digestibility of herbivorous and omnivorous diets compared to their insectivorous source population.

Conclusions:

• Dietary shifts in Podarcis siculus are associated with localized hindgut physiological changes, particularly in enzyme activity and microbial communities.
• These adaptations enhance the ability of lizards to digest plant material, facilitating survival on omnivorous diets.
• The study supports the adaptive modulation hypothesis, highlighting the role of diet in shaping digestive physiology.