1. Ecology
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Implications of being born late in the active season for growth, fattening, torpor use, winter survival and fecundity

  1. Britta Mahlert
  2. Hanno Gerritsmann
  3. Gabrielle Stalder
  4. Thomas Ruf
  5. Alexandre Zahariev
  6. Stéphane Blanc
  7. Sylvain Giroud  Is a corresponding author
  1. Research Institute of Wildlife Ecology, University of Veterinary Medicine, Austria
  2. Université de Strasbourg, IPHC, France
  3. CNRS, UMR7178, France
Research Article
Cite as: eLife 2018;7:e31225 doi: 10.7554/eLife.31225
5 figures, 4 tables and 9 additional files

Figures

Changes in (a) structural growth (body length), (b) body mass, (c) total torpor duration, (d) energy intake and (e) activity time of early (‘EB’) and late-born (‘LB’) female juvenile garden dormice either fed ad libitum (‘AL’) or intermittently fasted (‘IF’) from the start of experiments until hibernation onset.

N = 6 individuals per group. Values are means ±SE. Torpor duration and activity time were estimated from measurements of nest temperature (for details see the ‘Material and methods’ part).

https://doi.org/10.7554/eLife.31225.003
Levels of (a) total energy expenditure and (b) water turnover of early and late-born female juvenile garden dormice either fed ad libitum (‘AL’) or intermittently fasted (‘IF’) prior to hibernation onset (weeks 11–12 for EB and weeks 7–8 for LB).

Groups differing significantly (p<0.05, Tukey’s post-hoc comparisons) are denoted by different superscripts.

https://doi.org/10.7554/eLife.31225.007
Changes in (a) torpor frequency and (b) mean torpor duration of early (‘EB’) and late-born (‘LB’) female juvenile garden dormice either fed ad libitum (‘AL’) or intermittently fasted (‘IF’) from the start of experiments until hibernation onset.

N = 6 individuals per group. Values are means ±SE. Torpor patterns were assessed by measurements of nest temperature (for details see the ‘Materials and methods’ part).

https://doi.org/10.7554/eLife.31225.008
Box-plot graphs of overwintering loss of body mass (‘BM’), fat-free mass (‘FFM’) and fat mass (‘FM’) of female juvenile garden dormice born early (‘Early-born Juveniles’) or late (‘Late-born Juveniles’) in the reproductive season.

Groups differing significantly (p<0.05, Tukey’s post-hoc comparisons) are denoted by different superscripts.

https://doi.org/10.7554/eLife.31225.010
Proportion of breeding occurrence (‘breeding proportion’) of early-born (‘EB’) and late-born (‘LB’) female garden dormice at early and late reproductive events.

Females were either fed ad libitum (AL) or intermittently fasted (‘IF’) during their juvenile period, that is, from the start of experiments until hibernation onset. Values are means ±SD.

https://doi.org/10.7554/eLife.31225.011

Tables

Table 1
Parameters of analyses of variance for the effects of group (early-born, late-born) and diet (fed ad libitum or intermittently fasted) on the rate (‘slope’) of body mass gain and structural growth (assessed by body length), the maximal level (‘plateau’) at which BM and BL levelled off and the time (‘time of plateau’) at which the plateau of BM or BL occurred during the pre-hibernation period.

p-values shown in bold correspond to statistically significant and interpretable values.

https://doi.org/10.7554/eLife.31225.004
ParameterTermResponse variables
SlopePlateauTime of plateau
F-valuep-valueF-valuep-valueF-valuep-value
Body massGroup
Diet
Group х Diet
70.93
1.00
3.58
<0.001
0.33
0.07
5.73
0.05
0.13
<0.05
0.83
0.72
368.71
0.07
0.44
<0.001
0.80
0.52
Body lengthGroup
Diet
Group х Diet
103.55
0.01
1.65
<0.001
0.92
0.21
1.46
0.01
0.12
0.24
0.97
0.73
190.11
0.43
0.29
<0.001
0.52
0.60
Table 2
Parameters of linear models for the effects of time, group (early-born, late-born) and diet (fed ad libitum or intermittently fasted) on body mass, fat mass and fat-free mass of juvenile garden dormice.

p-values shown in bold correspond to statistically significant and interpretable values.

https://doi.org/10.7554/eLife.31225.005
Response variableTermEstimate ± SDt-valuep-value
Body mass (g)Time
Group
Diet
Time x Group
Time x Diet
Group x Diet
34.39 ± 2.17
−9.13 ± 4.36
−5.36 ± 4.89
−16.63 ± 2.71
−0.79 ± 2.73
9.14 ± 6.26
15.85
−2.09
−1.10
−6.14
0.29
1.46
<0.001
0.06
0.29
<0.001
0.78
0.17
Fat mass (g)Time
Group
Diet
Time x Group
Time x Diet
Group x Diet
29.68 ± 1.70
−3.61 ± 2.80
−2.52 ± 3.10
−13.36 ± 2.11
−2.02 ± 2.13
5.41 ± 3.90
17.49
−1.29
−0.81
−6.32
−0.95
1.39
<0.001
0.22
0.43
<0.001
0.36
0.19
Fat-free mass (g)Time
Group
Diet
Time x Group
Time x Diet
Group x Diet
4.72 ± 0.86
−5.36 ± 1.95
−2.82 ± 2.20
−3.45 ± 1.07
1.19 ± 1.08
3.76 ± 2.83
5.48
−2.75
−1.28
−3.21
1.10
1.33
<0.001
<0.05
0.22
<0.01
0.29
0.21
Table 3
Means and standard deviations for pre- and post-hibernation body mass, fat mass and fat-free mass of the experimental animal groups, according to the time of birth (early-born ‘EB’, late-born ‘LB’) and feeding treatment (ad libitum ‘AL’ and intermittently fasted ‘IF’).

Groups differing significantly (p<0.05, Tukey’s post-hoc comparisons) are denoted by different superscripts.

https://doi.org/10.7554/eLife.31225.006
VariableTimeGroupMean ± SD
Body mass (g)Pre-hibernation



Post-hibernation
EB-AL
EB-IF
LB-AL
LB-IF
EB-AL
EB-IF
LB-AL
LB-IF
100.0 ± 0.7a
101.8 ± 2.1a
77.4 ± 1.3b
77.3 ± 2.1b
65.7 ± 0.4c
63.7 ± 1.0c
59.3 ± 0.6c
60.5 ± 1.7c
Fat mass (g)Pre-hibernation



Post-hibernation
EB-AL
EB-IF
LB-AL
LB-IF
EB-AL
EB-IF
LB-AL
LB-IF
47.5 ± 0.6a
49.2 ± 1.4a
32.6 ± 1.0b
32.3 ± 1.3b
18.5 ± 0.2c
18.0 ± 0.7c
15.5 ± 0.4c
17.6 ± 0.9c
Fat-free mass (g)Pre-hibernation



Post-hibernation
EB-AL
EB-IF
LB-AL
LB-IF
EB-AL
EB-IF
LB-AL
LB-IF
52.5 ± 0.4a
52.6 ± 0.7a
44.8 ± 0.5bc
44.9 ± 0.9bc
47.2 ± 0.5bc
45.7 ± 0.4c
43.9 ± 0.5c
43.0 ± 4.3c
Table 4
Parameters of analyses of variance for the effects of group and diet on the time (‘starting time’) and the rate (‘slope’) of torpor increase or decrease of activity time.

Mean torpor duration was also added as a predictor variable in the model for activity time and mean ambient temperature was included as a random effect in all models. p-values shown in bold correspond to statistically significant and interpretable values.

https://doi.org/10.7554/eLife.31225.009
Response variableTermParameters
Starting timeSlope
χ2p-valueχ 2p-value
Torpor frequencyGroup
Diet
Group х Diet
46.47
8.64
1.82
<0.001
<0.01
0.18
3.16
1.18
7.02
0.08
0.28
<0.01
Mean torpor durationGroup
Diet
Group х Diet
43.49
8.84
0.50
<0.001
<0.01
0.48
38.26
0.35
16.64
<0.001
0.55
<0.001
Total torpor durationGroup
Diet
Group х Diet
43.49
8.84
0.50
<0.001
<0.01
0.48
77.86
0.55
9.66
<0.001
0.46
<0.01
Activity timeGroup
Diet
Group х Diet
Mean torpor duration
0.09
14.06
6.96
7.61
0.76
<0.001
<0.01
<0.01
6.45
2.64
0.22
2.68
<0.05
0.10
0.64
0.10

Additional files

Supplementary file 1

Parameters of linear models for the effects of group and diet on total energy expenditure and water turnover of juvenile garden dormice.

Body mass was also assessed as an explanatory variable in the models. p-Values shown in bold correspond to statistically significant and interpretable values.

https://doi.org/10.7554/eLife.31225.012
Supplementary file 2

Means ± standard errors and parameters of analyses of variance for the effects of group (early-born ‘EB’ vs. late-born ‘LB’), diet (ad-libitum ‘AL’ vs. intermittently fasted ‘IF’) and time (‘start of growth’ vs. ‘body mass plateau’) on average daily metabolic rate (‘ADMR’) of garden dormice, metabolic rate during night (‘MR-night’) and metabolic rate during day (‘MR-day’).

Metabolic rate is expressed in ml O2 h−1 g−1. Body mass and animal ID were included as random effects in all models. p-Values shown in bold correspond to statistically significant and interpretable values.

https://doi.org/10.7554/eLife.31225.013
Supplementary file 3

Means and standard errors for the time (‘starting time’) and rate (‘slope’) of increase in torpor frequency, mean and total torpor duration of early-born (‘EB’) and late-born (‘LB’) juvenile garden dormice, either fed ad libitum (‘AL’) or intermittently fasted (‘IF’).

https://doi.org/10.7554/eLife.31225.014
Supplementary file 4

Parameters of linear models for the effects of group and diet on the hibernation duration, arousal frequency, mean torpor and arousal durations and minimal body temperature (Tb) during winter.

Hibernation duration was also assed as an explanatory variable in the model for arousal frequency. p-Values shown in italic correspond to statistically significant and interpretable values.

https://doi.org/10.7554/eLife.31225.015
Supplementary file 5

Means and standard deviations for the hibernation duration, arousal frequency, mean torpor and arousal durations and minimal body temperature (Tb) of juveniles during winter, according to their time of birth (early-born ‘EB’, late-born ‘LB’) and feeding treatment (ad libitum ‘AL’ and intermittently fasted ‘IF’).

https://doi.org/10.7554/eLife.31225.016
Supplementary file 6

Parameters of analyses of variance for the effects of time, group and diet on body mass and body mass changes of juvenile garden dormice during the post-hibernation breeding period.

Body mass changes were computed between post-hibernation and the start of early breeding, and between the start of early breeding and the start of late breeding. p-Values shown in bold correspond to statistically significant and interpretable values.

https://doi.org/10.7554/eLife.31225.017
Supplementary file 7

Means and standard deviations of body mass at post-hibernation, start of early breeding and start of late breeding, as well as body mass changes between pre-hibernation and the start of early breeding, and between the start of early breeding and the start of late breeding of the experimental animal groups, according to the time of birth (early-born ‘EB’, late-born ‘LB’) and feeding treatment (ad libitum ‘AL’ and intermittently fasted ‘IF’).

Groups differing significantly (p<0.05, Tukey’s post-hoc comparisons) are denoted by different superscripts.

https://doi.org/10.7554/eLife.31225.018
Supplementary file 8

Parameters of generalized linear models (in the case of breeding proportion) or linear models (in the case of litter size and litter mass) for the effects of timing of reproduction, group and diet on the female breeding proportion, litter size and litter mass.

p-Values shown in bold correspond to statistically significant and interpretable values.

https://doi.org/10.7554/eLife.31225.019
Transparent reporting form
https://doi.org/10.7554/eLife.31225.020

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