1. Ecology
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Parental effects alter the adaptive value of an adult behavioural trait

  1. Rebecca M Kilner  Is a corresponding author
  2. Giuseppe Boncoraglio
  3. Jonathan M Henshaw
  4. Benjamin JM Jarrett
  5. Ornela De Gasperin
  6. Alfredo Attisano
  7. Hanna Kokko
  1. University of Cambridge, United Kingdom
  2. Australian National University, Australia
  3. Polish Academy of Sciences, Poland
  4. University of Zürich, Switzerland
Research Article
Cite this article as: eLife 2015;4:e07340 doi: 10.7554/eLife.07340
5 figures, 2 tables and 1 data set

Figures

Figure 1 with 2 supplements
Overview of the model structure, including mortality and survival (A) and reproduction (B).
https://doi.org/10.7554/eLife.07340.003
Figure 1—figure supplement 1
Longevity of adult virgin males (n = 43) and females (n = 50) (A) shown as a cumulative survival plot and (B) comparing mean ± S.E.M lifespan for each sex.

The rate at which the beetles died was not significantly different, nor was there a difference in their mean lifespan (X2 = 0.69, d.f. = 1, p = 0.41). These data were collected from an experiment in which individuals were removed at eclosion from 13 different families at random, with each family contributing between 2 and 13 experimental subjects. The experimental subjects were weighed and kept under standard conditions (see ‘Materials and methods’) until they died. The population was censused twice a week. In the statistical analyses reported above, body mass at eclosion and sex were fixed terms and family of origin was a random term, using the R package coxme (see ‘Materials and methods’).

https://doi.org/10.7554/eLife.07340.004
Figure 1—figure supplement 2
Frequency distribution of the size of field-caught N. vespilloides (shown in blue) and the experimental N. vespilloides described in this study (shown in red).

The size of the beetle is given by its pronotum width. There is no sexual size dimorphism, so the data for males and females have been pooled. Our experimental treatments generated beetles that were well within the range of size of beetles that occur naturally.

https://doi.org/10.7554/eLife.07340.005
The effect of the mother's early-life environment on (A) brood mass at the dispersal stage of development and (B) her lifespan after reproduction.

Mothers raised cross-fostered broods of either 5 (white circles) or 20 larvae (black circles), singlehandedly. A poor quality environment in early life generates mothers that (A) are less effective at raising broods of 20 cross-fostered larvae and (B) exhibit lower subsequent survival than mothers raised in a good quality early-life environment. Mean values with standard error bars are shown.

https://doi.org/10.7554/eLife.07340.007
The effect of the father's early-life environment on (A) brood mass at the dispersal stage of development and (B) his lifespan after reproduction.

Fathers raised cross-fostered broods of either 5 (white circles) or 20 larvae (black circles), singlehandedly. A poor quality environment in early life generates fathers that (A) are less effective at raising broods of 20 cross-fostered larvae and (B) tend to exhibit lower subsequent survival than fathers raised in a good quality early-life environment. Mean values with standard error bars are shown.

https://doi.org/10.7554/eLife.07340.008
The effect of the female's early-life environment (i.e., the duration of care she received as a larva) on her lifespan after reproduction (white bars), and on the lifespan of the male with whom she raised offspring (black bars).

All males developed in a high-quality environment. The greater the difference within the pair in the environment they each experienced during development, the greater the difference in their subsequent lifespan. Low-quality mothers thus exploit high-quality fathers. Mean values with standard error bars are shown.

https://doi.org/10.7554/eLife.07340.009
The relationship between the average care received by a brood and the strength of parental effects αF (i.e., the extent to which care received affects the future parental quality of offspring).

Average care levels increase with the strength of parental effects both when sexual conflict is present (circles) and when it is absent (squares). When there is no sexual conflict, parents provide more care in absolute terms and also increase their care more steeply with increasing parental effects. Shown with g1 = 0.5, bmin = fmin = 1, αB = 5, βG = 5, βP = 5, and mmin = 0.25 (see Appendix 1 for details of function shapes).

https://doi.org/10.7554/eLife.07340.011

Tables

Table 1

Results from Experiment 1: the influence of parental effects on the costs and benefits of parental care provided in adult life

https://doi.org/10.7554/eLife.07340.006
Female-only care
EstimateStandard errort valuep value
a. Effect on brood mass (benefit of care)
Intercept0.072940.706540.103
Duration of care as larva−0.014300.09597−0.1490.010
Brood size raised as adult2.415420.0868927.797<0.0001
Carcass mass0.014510.016090.9020.345
Female pronotum0.126630.122701.0320.282
Duration of care as larva x brood size raised as adult0.446230.121503.6730.0004
CoefficientStandard errorz valuep value
b. Effect on maternal survival (cost of care)
Duration of care as larva0.3590.3421.050.290
Brood size raised as adult0.8530.3542.410.016
Carcass mass0.0590.0591.000.320
Female pronotum0.1350.4530.300.770
Duration of care as larva x brood size raised as adult−1.2860.507−2.540.011
Male-only care
EstimateStandard errort valuep value
c. Effect on brood mass (benefit of care)
Intercept0.605530.254152.383
Duration of care as larva0.044450.043071.0320.0002
Brood size raised as adult0.756720.0381819.820<0.0001
Carcass mass0.018800.005723.2870.001
Male pronotum−0.014500.04675−0.3100.785
Duration of care as larva x brood size raised as adult0.201900.054063.7350.0002
CoefficientStandard errorz valuep value
d. Effect on paternal survival (cost of care)
Duration of care as larva0.1830.3520.520.600
Brood size raised as adult0.6860.3342.050.040
Carcass mass0.0760.0531.420.160
Male pronotum−0.4480.385−0.120.910
Duration of care as larva x brood size raised as adult−0.8560.474−1.810.071
  1. Parental effects were created experimentally by exposing experimental subjects to either 0 hr or 24 hr of post-hatching care as larvae. They were then kept until adulthood and given broods of either 5 or 20 cross-fostered larvae to raise as a single parent. Their lifespan thereafter was recorded. Further details are given in the ‘Materials and methods’.

Table 2

Results from Experiment 2: the influence of parental effects on the outcome of a social interaction

https://doi.org/10.7554/eLife.07340.010
NB parental effect experienced by femaleCoefficientStandard errorz valuep value
a. Female lifespan
 Parental effect: 8 hr vs 0 hr0.4270.2281.880.061
 Parental effect: 24 hr vs 0 hr0.2160.2360.920.360
 Parental effect: 192 hr vs 0 hr−0.0730.254−0.290.770
 Total carcass mass0.0170.0161.060.290
 Total brood mass0.0040.0290.160.870
 Female pronotum0.5220.3221.620.110
NB parental effect experienced by male's partnerCoefficientStandard errorz valuep value
b. Male lifespan
 Parental effect: 8 hr vs 0 hr−0.1090.235−0.470.640
 Parental effect: 24 hr vs 0 hr−0.6640.252−2.630.008
 Parental effect: 192 hr vs 0 hr−1.0330.291−3.550.0003
 Total carcass mass−0.0270.023−1.170.240
 Total brood mass−0.0940.032−2.870.004
 Male pronotum0.9150.3662.500.012
NB parental effect experienced by brood's motherEstimateStandard errorz valuep value
c. Brood size
 Intercept1.357760.392863.4560.0005
 Parental effect: 8 hr vs 0 hr0.023500.032950.7130.476
 Parental effect: 24 hr vs 0 hr0.162610.034534.710<0.0001
 Parental effect: 192 hr vs 0 hr0.146410.036763.983<0.0001
 Total carcass mass0.007650.003082.4850.013
 Female pronotum0.311900.051336.076<0.0001
 Male pronotum0.129730.057292.2650.024
  1. Parental effects were created experimentally by exposing females to 0 hr, 8 hr, 24 hr, or 192 hr of post-hatching care as larvae. They were then kept until adulthood and allowed to breed twice with a male who had received 192 hr of care as larva. The two parents raised offspring together. Each parent's lifespan thereafter was recorded, as was the mass of their brood at dispersal. Further details are given in the ‘Materials methods’.

Data availability

The following data sets were generated
  1. 1

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