Corticosterone Contributes to Diet-Induced Reprogramming of Post-Metamorphic Behavior in Spadefoot Toads.

Area of Science:

• Developmental biology
• Endocrinology
• Behavioral ecology

Background:

• Early life stress can cause lasting phenotypic effects into adulthood, often mediated by glucocorticoids like corticosterone.
• Nutrient restriction is known to alter later life behaviors and stress responses via corticosterone.
• The role of corticosterone in carryover effects from novel dietary resources remains unexplored.

Purpose of the Study:

• To investigate if corticosterone is mechanistically involved in carryover effects induced by a novel diet in plains spadefoot larvae.
• To determine if experimentally elevated corticosterone levels in larvae mimic diet-induced carryover effects on juvenile behavior and stress axis activity.

Main Methods:

• Plains spadefoot (Spea bombifrons) larvae were fed either a novel shrimp diet or a standard detritus diet.
• Larvae were also experimentally treated with exogenous corticosterone.
• Juvenile behavior (food seeking, locomotor activity) and corticosterone levels were measured post-metamorphosis.

Main Results:

• Shrimp-fed larvae exhibited elevated corticosterone levels and altered juvenile behaviors, including increased food seeking and activity.
• Experimental corticosterone treatment in larvae partially replicated these behavioral changes in juveniles.
• However, larval corticosterone exposure did not alter juvenile corticosterone levels, unlike the shrimp diet.

Conclusions:

• Corticosterone-related mechanisms likely contribute to carryover effects from novel diets in plains spadefoots.
• Diet-induced carryover effects are not solely driven by corticosterone, indicating other factors are involved.
• This study highlights the complex interplay between diet, hormones, and developmental plasticity.