Seasonal differences in energy-saving mechanisms during

lipid membranes. (Geiser 1991; Falkenstein et al. 2001). Increase in cellular damages. Hexanoyl-Lysine (HEL): marker of initial phases of peroxidation ...
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6-12 August 2008, Swakupmund, Namibia

Seasonal differences in energy-saving mechanisms during food restriction in a Malagasy primate

Sylvain Giroud1,2, Stéphane Blanc1, Hugues Oudart1, Caroline Gilbert1 and Martine Perret2 1 IPHC

- Department of Ecology, Physiology and Ethology - CNRS and Strasbourg University - France 2 Department of Ecology and Biodiversity Management - CNRS and MNHN Brunoy - France

Background Global Changes

Environment with low food availability

loss

MASS

gain

Food deprivation

Limits?

Energie Ingested ingérée Energy

∆ Body Reserves Physiological Mechanisms of Energy Savings

Survival Reproduction

Fitness

Energy Expenditure

Madagascar: - Critical hotspot for biodiversity conservation - High endemism level - Highly contrasted climate

Background

Seasonal variability in trophic resources

Cold and dry season

80

Heterothermy Seasonal fattening

Minimal T °C

120

100

Microcebus murinus

35

140

30

120

25 20

60 15 40

10

% of variations

Rainfall (mmH2O) Resources

The Grey mouse lemur

Torpor

100

Resting metabolism

80 60

No Torpor

Body mass Sexual rest

Season of reproduction

Dry season

20

A S

O N D

J

F

M A M J

J

A S

Ecological constraints

Seasonal variations of several biological parameters in percentage of the annual average

Adaptive mechanisms of energy and water economy Perret 1998; Perret and Aujard 1999; Schmid 2000

Background

Global Climate Changes El Niño phenomenon Rainfall (mmH2O) Resources

Minimal T °C 35

120

100

Cold and dry season

80

30 25 20

60 15 40

10

 Unpredictable events

?

20

A S

O N D

J

F

M A M J

J

A S

Reproductive season Fattening processes

Physiological plasticity

Question

In M. murinus facing a chronic food shortage: - Nature and limits of physiological plasticity? - Impacts of adaptive mechanisms on organism?

Experimental protocol - part 1

Male Mouse lemurs

Short-days SD Winter-like

Summer-like

10-day control period Stable energy balance Before

Long-days LD

40 and 80% 35-day food restriction Continuous telemetry recording

Changes in

After

• Body mass • Total energy expenditure and body composition (doubly-labeled water)

• Resting metabolic rate (respirometry) • Body temperature and torpor pattern (telemetry)

100

**

40 20

80

40

SD40

SD80

Ad Libitum Food-restricted

**

30 20

NS

10 0

-30%

LD40

-36%

LD40

*

-23%

0

Fat Mass (g)

40

-23%

50

-8%

60

20

**

60

0

-15%

Body Mass (g)

120

NS

-13%

*

**

80

**

-3%

No data on energetic

100

-12%

LD80: survival-threatened body mass reached

Fat-Free Mass (g)

Results - part 1: Body mass and body composition

SD40

SD80

Total Energy Expenditure **

80

-36%

-21%

0

-12%

40

Resting Metabolic Rate 60

**

40

-22%

0

-9%

20

LD40

SD40

SD80

Ad Libitum

Food-restricted

Duration (min)

*

Hypothermia duration

1200

(Tb