Aurélie C OHAS Christophe B ONENFANT Dominique A LLAINE

1. EFFECTS OF SUMMER ENVIRONMENTAL FLUCTUATIONS ON SURVIVAL OF ALPINE MARMOT Aurélie COHAS ChristopheBONENFANT DominiqueALLAINE Laboratoire Biométrie et Biologie évolutive Université Claude Bernard Lyon 1 43 Bd du 11 novembre 1918 69622 Villeurbanne France

2. Climate effects on demography Climate change => how climate acts on demography = necessity to assess the trajectory of species Environmental conditions affect individuals’ performancethrough: - direct effects - indirect effects via primary productivity • => Assess impact of summer climate on marmots survival, using long-term data on individually identified marmots

3. Field site 40 ha of alpine meadow located in the Grande Sassière national reserve (French Alps, 2340 m above see level)

4. Field protocol From 1990 to 2007: 20 families studied 798 marked individuals 1621 encounters For each family: number age sex social status of individuals known

5. Environmental variables • Climate • 2 local variables: • Summer temperature (STemp)

6. Climatic variables: Local variables - Temperature May October => Summer temperature (STemp)

7. Environmental variables • Climate • 2 local variables: • Summer temperature (STemp) • Summer rainfall (SRain)

8. Climatic variables: Local variables - Rainfall May October => Summer rainfall (SRain)

9. Environmental variables • Climate • 2 local variables: • Summer temperature (STemp) • Summer rainfall (SRain) • Vegetation • Vegetation availability in spring (sNDVI)

10. Vegetation index Normalized Difference Vegetation Index (NDVI) difference from the visible and near-infrared light reflected by vegetation Abundant vegetation absorbs visible light reflects near-infrared light => HIGH NDVI Sparse vegetation reflects visible light absorbs near-infrared light => LOW NDVI near infraredvisible near infraredvisible 40% 30% 50% 8%

11. Vegetation index - Normalized Difference Vegetation Index (NDVI) 15th of April => vegetation availability in spring (sNDVI)

12. Predictions • Prediction 1 • Positive effect of proxys of primary productivity on survival • higher temperature => less vegetation => lower survival • more rain => more vegetation => higher survival • early vegetation availability => higher survival • BUT possible thermoregulation cost in marmots • more rain => low survival • Prediction 2 • Higher environmental effects for young than for adults • Prediction 3 • Presence of helpers buffers environmental effects on juvenile survival

13. Estimating survival

14. Model and Explanatory variables Capture history: 1001101220 => capture probability not 1 => Multistate capture-recapture model to take into account capture probability and social status

15. Survival Apparent survival Age effect => survival increase with age

16. Survival Dominant Subordinate Social status effect => dominant show higher survival than subordinates due to dispersal effect

17. Survival Helpers No helpers Helpers effect => Juveniles show higher survival in presence of helpers

18. Survival Marked temporal variation

19. Effects of summer environmental fluctuations on survival

20. De-trend of the environmental variables Environmental variables show tendency => Necessity to de-trend variables = use of residuals of linear regression between variable and year Example of de-trending with STemp Increasing trend

21. De-trend of the environmental variables Environmental variables show tendency => Necessity to de-trend variables = use of residuals of linear regression between variable and year Correlation coefficient between de-trended variables No significant correlation

22. Effects of the environmental variables • For each age class separately, • Test whether fluctuations of each environmental variable correlates with survival variations

23. Juveniles => Positive effect of availability of vegetation in spring on juvenile survival => Positive effect more important in absence of helpers (with: 0.06±0.16, without: 0.74±0.23, p=0.02)

24. Juveniles 26.4% of deviance explained by environmental variables => Negative effect of summer precipitation on juvenile survival (-0.23±0.11, p=0.06)

25. Yearlings No effect of any of the summer environmental variables Two year olds and subordinate adults No effect of any of the summer environmental variables

26. Dominant adults => Negative effect of summer temperature on dominant marmots survival (-0.33±0.17, p=0.02) => Positive effect of summer rain on dominant marmots survival (0.40±0.21,p=0.06) 33.8% of deviance explained by environmental variables

27. Back to predictions • Prediction 1 PARTIALLY SUPPORTED • Positive effect of proxys of primary productivity on survival • higher temperature => less vegetation => lower survival in dominants • more rain => more vegetation => higher survival in dominants • early vegetation availability => higher survival in juveniles • BUT possible thermoregulation cost in marmots • more rain => low survival in juveniles

28. Prediction 1 Positive effects of proxys of primary productivity on survival • PARTIALLY SUPPORTED • Climate = > Food availability • Food availabilityseems a limiting factor • for dominant adults through food availability during summer • for juveniles through food availability early in spring • => mother condition • + match plant phenology / emergence • BUT for juveniles evidence of direct cost • heavy rain => thermoregulation costs => behavioral thermoregulation => no access to food => lower survival

29. Back to predictions • Prediction 1 PARTIALLY SUPPORTED • Positive effect of proxys of primary productivity on survival • higher temperature => less vegetation => lower survival in dominants • more rain => more vegetation => higher survival in dominants • early vegetation availability => higher survival in juveniles • BUT possible thermoregulation cost in marmots • more rain => low survival in juveniles • Prediction 2 PARTIALLY SUPPORTED • Higher environmental effects for young than for adults

30. Prediction 2 Higher environmental effects for young than for adults • PATIALLY SUPPORTED • Juveniles SENSIBLE to environmental fluctuations • Yearlings NOT SENSIBLE to environmental fluctuations • Two year olds NOT SENSIBLE to environmental fluctuations • Subordinate adults NOT SENSIBLE to environmental fluctuations => Theory for long lived species: sensibility to environmental fluctuations decreases with age BUT dominant adults SENSIBLE to environmental fluctuations => Possible cost of dominance and reproduction

31. Back to predictions • Prediction 1 PARTIALLY SUPPORTED • Positive effect of proxys of primary productivity on survival • higher temperature => less vegetation => lower survival in dominants • more rain => more vegetation => higher survival in dominants • early vegetation availability => higher survival in juveniles • BUT possible thermoregulation cost in marmots • more rain => low survival in juveniles • Prediction 2 PARTIALLY SUPPORTED • Higher environmental effects for young than for adults • Prediction 3 SUPPORTED • Presence of helpers buffers environmental effects on juvenile survival

32. Prediction 3 Presence of helpers buffers environmental effects on juvenile survival • SUPPORTED • Juveniles • with helpers LOW SENSIBILITY to environmental fluctuations • without helpers HIGH SENSIBILITY to environmental fluctuations => Weight at entry in hibernation is driven by food availability but being fat is more critical for juveniles without helpers than for juveniles with helpers

33. Conclusions Age specific and complex effects of environment on survival - climate impacts survival via primary productivity - but effects modulated by social factors =>Next step: - taking into account winter conditions - quantifying impact of these effects on marmot population growth rate

34. Acknowledgements to all students involved in marmots trapping and observations to the authorities of the Vanoise National Park

35. Many thanks for your attention