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Seasonal Changes in Juvenile Song Sparrow Corticosterone and d 15 N Are Not Food-Dependent

Seasonal Changes in Juvenile Song Sparrow Corticosterone and d 15 N Are Not Food-Dependent. Liana Zanette 1 , Michael Clinchy 2 , Bethany Kempster 1. 1 University of Western Ontario, London, CA, 2 University of Victoria, Victoria, CA. Victoria Study. Food & Predator Effects on.

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Seasonal Changes in Juvenile Song Sparrow Corticosterone and d 15 N Are Not Food-Dependent

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  1. Seasonal Changes in Juvenile Song Sparrow Corticosterone and d15N Are Not Food-Dependent Liana Zanette1, Michael Clinchy2, Bethany Kempster1 1University of Western Ontario, London, CA, 2University of Victoria, Victoria, CA

  2. Victoria Study Food & Predator Effects on..... Physiology Behaviour Mating Strategies Demography

  3. Victoria Study Food added to 50+ territories Controls 50+ territories

  4. Coastal Islands Victoria Victoria Study Low Predator Pressure High Predator Pressure

  5. High Predator Pressure Low Predator Pressure Victoria Study: Food & Pred Effects on Chronic Stress in Adults Clinchy, Zanette, Boonstra, Wingfield, Smith.2004. PRSB 271:2473

  6. Victoria Study Food & Predators On..... Maternal Effects (We’re starting with food)

  7. Maternal Effects in Relation to FOOD: Two Sources of Data Data on nestlings as part of Victoria field study Data on nestlings as part of London lab study

  8. Assessing Nestling Condition in the Field is Problematic Victoria Field Study... Collect standard measures of nestling condition (mass, tars etc...) About 200 nestlings/year Tons of variability

  9. Stable Isotopes as an Index of Nestling Condition? London Lab Study..... Can stable nitrogen isotopes give us this signature of nestling condition?

  10. Stable Isotopes as an Index of Nutritional Stress? POTENTIAL FIELD USE Nutritionally stressed quail chicks enriched in 15N Potential use because Hobson et al. is THE study Hobson, Alisauskas, Clark. 1993. Condor 95:388

  11. London Lab Study Nestlings taken from field to lab (constant light:dark, temp. etc...) Hand-reared to day 23 Feeding treatment: Ad Libitum or Food-Restricted Measured morphology, brain development, physiology and stable isotopes Squidges from field Hand-rearing nestlings

  12. 22 20 18 16 14 Mass (g) 12 Ad libitum 10 Food stressed 8 0 5 10 15 20 25 Age (days post-hatch) Food Affects Morphology

  13. Male Female Male Female AD LIBITUM FOOD- RESTRICTED Food Affects Brain Development 0.6 0.4 HVC Volume (mm3) 0.2

  14. Food Affects Physiology Trait Ad libitum Stressed Treatment effect Baseline Cort (ng/ml) 15.2 ± 2.1 28.7 ± 4.3 p = 0.014 Glucose (mmol/L) 22.3 ± 0.08 23.0 ± 0.07 p = 0.016 Hematocrit 0.63 ± 0.01 0.59 ± 0.01 p = 0.046 Physiological indicators work great! Cort assay thanks to: John Wingfield and Lab + E-Bird Canada

  15. Food- Restricted Ad Libitum Food Does NOTAffect Stable Isotopes 2.00 Δ15N (blood) 1.00

  16. Evidence of Maternal Effects? Seasonal Effect on Δ15N NOT due to rearing environment 2.60 2.40 2.20 N Blood (‰) 2.00 15 1.80 Has to be related to the egg MATERNAL EFFECT! 1.60 1.40 140 160 180 200 Hatch Date (Julian)

  17. Evidence of Maternal Effects? Seasonal Effect on Baseline Cort. 40.0 30.0 Base Corticosterone (ngml) 20.0 10.0 0.0 140 160 180 200 Hatch Date (Julian)

  18. 22.6 22.2 21.8 21.4 21.0 140 150 160 170 180 190 200 210 Evidence of Maternal Effects? Seasonal Effect on Morphology Tarsus (mm) Hatch Date (Julian)

  19. Tarsus 22.6 2.2 21.8 2.1 21.0 2.0 Mass/Tarsus3 Mass 1.9 21.0 1.8 20.0 1.7 19.0 140 150 160 170 180 190 210 200 18.0 140 150 160 170 180 190 200 210 Evidence of Maternal Effects? Seasonal Effect on Allometry Hatch Date (Julian)

  20. 0.10 0.09 0.08 HVC Volume 0.07 0.06 0.05 140 150 160 170 180 190 200 Hatch Date (Julian) Evidence of Maternal Effects? Seasonal Effect on Brain Development

  21. 35 25 15 Base Corticosterone (ngml) 5 100 120 140 160 Hatch Date (Julian) Evidence of Maternal Effects in the Field? Seasonal Effect on Baseline Cort.

  22. Maternal effects by what means? Seasonal effects reflect seasonal deterioration in mother’s condition Seasonal effects reflect maternal programming independent of her condition (e.g. photoperiod)

  23. What and where to go next? 1) How to “pitch” the current results? 2) Clearly more lab work..... -which hormone(s)? -measure eggs, kids + mom? 3) What relevance to the field?

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