Short communication: Elevated testosterone correlates with enhanced innate immune function in a cooperatively...

Area of Science:

• Endocrinology
• Immunology
• Behavioral Ecology

Background:

• Elevated testosterone is often linked to compromised immune function in vertebrates, suggesting a survival-reproduction trade-off.
• This trade-off may be less pronounced in cooperative breeding species due to reduced social conflict and sexual selection.

Purpose of the Study:

• To investigate the relationship between testosterone, cortisol, and innate immunity in male Damaraland mole-rats (Fukomys damarensis).
• To test whether traditional endocrine-immune trade-off models apply to eusocial species with minimal reproductive competition.

Main Methods:

• Assessed innate immunity using microbial killing assays (MKAs) and white blood cell counts.
• Measured urinary testosterone and cortisol concentrations in captive male Damaraland mole-rats.
• Analyzed correlations between hormone levels and immune metrics, controlling for age, body mass, and reproductive status.

Main Results:

• Urinary testosterone concentration was positively correlated with immune strength, specifically antimicrobial capacity and total white blood cell count.
• Testosterone levels were not significantly related to independent immune cell differentials.
• Cortisol, reproductive status, age, and body mass showed limited effects on immune metrics.

Conclusions:

• Findings challenge the generalized endocrine-immune trade-off model, suggesting testosterone may signal physiological condition in cooperative breeders.
• In Damaraland mole-rats, testosterone appears to be associated with enhanced immune function rather than immunosuppression.
• This study highlights species-specific variations in the endocrine-immune interactions, particularly in social systems.