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Testosterone Coordinates Gene Expression Across Different Tissues to Produce Carotenoid-Based Red Ornamentation
Sarah Khalil1,2,3, Erik D Enbody4, Carolina Frankl-Vilches5
1Department of Ecology and Evolutionary Biology, Tulane University, New Orleans, LA, USA.
Molecular Biology and Evolution
|March 13, 2023
Summary
Testosterone regulates carotenoid pigment production in birds, influencing red plumage color important for mate choice. This study reveals key genes and hormonal pathways involved in carotenoid metabolism and deposition in feathers.
Area of Science:
- Animal Behavior
- Genomics
- Biochemistry
Background:
- Carotenoid pigments are crucial for visual signals in vertebrate mate choice, but their production pathways are complex and not fully understood.
- Red plumage in male red-backed fairywrens (Malurus melanocephalus) is a key sexual signal, yet the mechanisms of its carotenoid-based coloration are unclear.
Purpose of the Study:
- To investigate the hormonal regulation of carotenoid-based trait production in birds.
- To identify genes involved in carotenoid metabolism, transport, and deposition in feather coloration.
Main Methods:
- Experimentally induced red plumage in male red-backed fairywrens by elevating testosterone levels.
- Compared gene expression in liver and feather follicles between control, testosterone-treated, and naturally ornamented males.
- Analyzed gene expression related to carotenoid and melanin pathways.
Main Results:
- Testosterone upregulated key genes (CYP2J19, ELOVL6) in the liver related to ketocarotenoid metabolism and processing.
- Testosterone regulated carotenoid transporter genes (ABCG1) in red feather follicles.
- In black feathers, carotenoid genes were downregulated, melanin genes upregulated, but carotenoids persisted, potentially due to BCO2 activity.
Conclusions:
- A foundational model for carotenoid-based trait production in wild birds is proposed.
- Testosterone is identified as a critical regulator of carotenoid-associated gene expression.
- Hormonal coordination across multiple tissues is suggested to underlie carotenoid trait development.
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