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testosterone juvenile hormone? corticosterone Gibberellins (+) abscisic acid (-) Environment Behavior physiology
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0153045 0 10 20 30 40 50 time (min) CORT (ng/ml) STRESSOR hypothalamus pituitary adrenal GLUCOCORTICOIDS Target tissue
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Corticosteroid Binding Globulin (CBG) STRESSOR hypothalamus pituitary adrenal GLUCOCORTICOIDS Target tissue CBG
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Laysan Albatross
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Kilauea Point NWR, Kauai Albatross Hill
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Albatross development time-line ~November ~January~July~June Mom lays egg Egg Hatches Chick grows (body growth) incubation Fledge! wing growth
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Albatross development time-line ~November ~January~July~June Mom lays egg Egg Hatches Chick grows (body growth) incubation Fledge! wing growth condition
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~November ~January~July~June Mom lays egg Egg Hatches Chick grows (body growth) incubation Fledge! wing growth -Late in the season, food availability is unpredictable -Body condition declines →CORT may go up with declining body condition! →CORT is elevated in some species before fledge ? What is the relationship between morphology, stress physiology, and fledging? Albatross development time-line condition
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Capture chicks (n = 14) every 4 days Morphological measurements (mass, wing length, tarsus, culmen) Blood samples Fledge Date
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Growth measures Wing LengthTarsus Length Days before fledgiing
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Linear Mixed Effects Model, p < 0.0001 Body Condition
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CORT CBG
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Free CORT
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Correlation poor good Body Condition v. free CORT
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Experimental Manipulation Captured chicks same as in first group (n = 8) Morphological measurements, blood samples Normal weight loss = 100-300g/4 days Fed chicks ~150g squid every 4 days
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LME, p < 0.0001 Body Condition – unfed
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* Fed birds still declined in body condition, but significantly less (LME, p < 0.05) Body Condition – unfed v. fed
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CORTCBG Unfedv. Fed
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t-test, p < 0.0001 Free CORT
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Age at Fledging
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Summary Approaching fledging, we see... ↓ Body Condition Accompanied by ↑CORT and ↓CBG – resulting in ↑↑ free CORT Body condition negatively correlated with free CORT Feeding... Reduction in the ↑CORT and ↓CBG, resulting in ↔ free CORT Delays fledging by average of 9 days
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TimeFledge at longest wing length Body Condition Fledge Free CORT Fledge Threshold Fledge
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Good Critical Body Condition Total CORT CBG capacity Nest abandonment Predictable Fasting in Albatross 2.02.53.03.5 0 100 200 300 400 500 600 700 800 goodpoor Body Condition (mass/culmen*100) CBG (nM specific binding) CBG
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