Physiological stress levels predict survival probabilities in wild rabbits

Area of Science:

• Endocrinology
• Animal Ecology
• Physiological Ecology

Background:

• Glucocorticoid hormones (corticosterone or cortisol) are crucial for short-term stress adaptation in vertebrates.
• The adaptive significance of chronic glucocorticoid elevation remains poorly understood.
• Understanding long-term stress responses is vital for conservation and wildlife management.

Purpose of the Study:

• To investigate the relationship between glucocorticoid physiology and fitness in European wild rabbits under long-term stress.
• To determine if serum corticosterone and fecal glucocorticoid metabolite levels predict body condition and survival probability.
• To elucidate the adaptive value of chronic stress hormone elevation.

Main Methods:

• Experimental exposure of European wild rabbits (Oryctolagus cuniculus) to a 2- to 4-week captive stressor.
• Measurement of serum corticosterone and fecal glucocorticoid metabolites.
• Assessment of body condition and survival probability upon release.

Main Results:

• Moderately elevated serum corticosterone and fecal glucocorticoid metabolites were negatively associated with body condition.
• These elevated glucocorticoid levels were positively associated with subsequent survival probability after release.
• A trade-off was observed: physiological costs (decreased body condition) were balanced by survival benefits.

Conclusions:

• The study suggests that moderate elevations in corticosterone under chronic stress represent an adaptive strategy in European wild rabbits.
• The findings highlight a balance between the energetic costs of maintaining high glucocorticoid levels and enhanced survival prospects.
• This research contributes to understanding the complex physiological adaptations to long-term environmental challenges in wildlife.