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Western University

Theses/Dissertations

2011

Stress

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The Relationship Between Hpa Regulation And Fitness In A Free-Living Population Of Song Sparrows (Melospiza Melodia), Ainsley Anne Furlonger Jan 2011

The Relationship Between Hpa Regulation And Fitness In A Free-Living Population Of Song Sparrows (Melospiza Melodia), Ainsley Anne Furlonger

Digitized Theses

In a changing environment, individuals must have the ability to physiologically cope with unpredictable stressors. The endocrine response to stressors is one mechanism vertebrates can use. The corticosterone (CORT)-fitness hypothesis predicts a negative relationship between acute stress induced levels of CORT and fitness. I examined the effectiveness of hypothalamo-pituitary-adrenal (HPA) axis regulation through exogenous hormone stimulation and plasma CORT levels as a predictor for various fitness measures in free-living song sparrows (Melospiza melodia). CORT levels at 30 minutes and in response to dexamethasone injection were predictive of lay date in this population. However, no relationships were observed between HPA regulation …