Temperature reorganises developmental time during thyroid hormone-driven fish metamorphosis

Area of Science:

• Endocrinology
• Developmental Biology
• Climate Change Biology

Background:

• Thyroid hormones (TH) are crucial for coordinating complex life cycles and metamorphosis in teleost fish.
• The impact of climate change-induced warming on fish developmental timing is not well understood.

Purpose of the Study:

• To investigate how elevated temperatures affect TH-driven developmental trajectories during fish metamorphosis.
• To elucidate the role of TH signaling in mediating temperature-sensitive developmental timing.

Main Methods:

• Transcriptomic time series analysis across six developmental stages in false clownfish (Amphiprion ocellaris).
• Application of time-series analyses and dynamic time warping to assess gene expression patterns.
• Reconstruction of endocrine gene networks at the gene level.

Main Results:

• Elevated temperatures accelerated TH synthesis and altered temporal responses in TH-signaling pathways.
• Key TH-dependent developmental programs, including differentiation and neuronal maturation, showed delayed and attenuated gene expression.
• Warming led to temporally uncoupled development, with accelerated initiation but impaired coordination of morphogenetic modules.

Conclusions:

• Thermal stress disrupts the precise endocrine timing mechanisms essential for orderly developmental transitions.
• Environmental warming can result in accelerated but functionally mismatched phenotypes due to disrupted developmental coordination.
• Thyroid hormone signaling is a critical mediator of temperature-sensitive developmental timing in vertebrates.