Sex and age shape mitochondrial function in a long-lived seabird.

Area of Science:

• Gerontology
• Mitochondrial Biology
• Avian Ecology

Background:

• Ageing is linked to declining individual performance and organismal fitness.
• Mitochondrial dysfunction is a proposed central mechanism in ageing, affecting cellular energy production.
• Age-related changes in mitochondrial function and sex differences remain understudied in wild populations.

Purpose of the Study:

• To investigate the effects of ageing on mitochondrial respiratory function in wild common terns (Sterna hirundo).
• To explore potential sex differences in age-related mitochondrial function.
• To assess the relationship between mitochondrial function, individual quality, and survival.

Main Methods:

• Studied 161 breeding common terns aged 2-24 years, with known sex.
• Measured mitochondrial respiratory function, including electron transport system activity, proton leak, and ATP production efficiency.
• Assessed individual repeatability of mitochondrial function between years.

Main Results:

• Older birds exhibited reduced maximum electron transport system activity and proton leak, indicating age-related decline in mitochondrial capacity.
• Mitochondrial efficiency in ATP production increased with age, suggesting it as a marker of individual quality.
• Females showed significantly higher mitochondrial respiration than males, potentially linked to egg-laying demands.

Conclusions:

• Mitochondrial respiratory function plays a role in physiological mechanisms underlying ageing and individual performance in wild animals.
• Increased mitochondrial efficiency with age may be a key factor for survival and individual quality.
• Consistent individual differences in mitochondrial function highlight its importance in long-term fitness.