2 published verifications about Thermal Stress Thermal Stress ×
“Sexual dimorphism is energetically costly to produce and maintain, and these energetic costs are expected to increase as environments become more thermally stressful.”
The claim is broadly supported, but the second half is stated more generally than the direct evidence allows. Energetic costs of sexually dimorphic traits are well documented, and thermal stress clearly increases metabolic demands and sex-specific trade-offs. What is less directly shown across taxa is the exact incremental cost of dimorphism itself under hotter conditions.
“Under thermal stress, elevated cortisol can reduce testosterone levels, affecting sexually dimorphic traits.”
The evidence supports the claim in broad terms. Heat or thermal stress can be associated with higher cortisol and lower testosterone, and glucocorticoids are well documented to suppress testosterone production. The main caveat is that heat can also lower testosterone through other pathways, so cortisol is a plausible mechanism, not always the sole or primary one; effects on sexually dimorphic traits are better supported for sustained hormone changes than for short-term stress.