Stress hormones mediate developmental plasticity in vertebrates with complex life cycles

Area of Science:

• Developmental biology
• Endocrinology
• Ecology

Background:

• Organismal development is shaped by environmental factors, leading to phenotypic plasticity.
• Chordates exhibit indirect development (larval stage) or direct development.
• Amphibian tadpoles display significant developmental plasticity influenced by environmental cues.

Purpose of the Study:

• To investigate the role of the neuroendocrine stress axis in mediating environmental effects on amphibian development.
• To understand how stress hormones influence tadpole morphology, metamorphosis timing, and carry-over effects on adult phenotype.
• To explore the adaptive significance and potential costs of stress-induced developmental plasticity.

Main Methods:

• Observational studies on amphibian tadpoles under varying environmental conditions.
• Hormonal assays to measure corticosterone (CORT) and thyroid hormone (TH) levels.
• Analysis of morphological and developmental timing changes in response to stressor exposure.

Main Results:

• Environmental stressors activate the neuroendocrine stress axis, increasing corticosterone (CORT) production.
• CORT influences tadpole morphology (e.g., tail growth) and interacts with thyroid hormone (TH) to regulate metamorphosis timing.
• Early life stress can lead to long-term changes in adult neuroendocrine function, behavior, and physiology, impacting fitness.

Conclusions:

• The neuroendocrine stress axis is a key mediator of developmental plasticity in amphibians.
• Stress-induced developmental changes can provide immediate survival benefits but may incur long-term fitness costs.
• Understanding these mechanisms is crucial for predicting organismal responses to environmental change across vertebrates.