Mean (+SE) lifespan of females that cared for larvae until they dispersed, either when widowed before hatching or when partners were present throughout the first brood.

<p>Mean (+SE) lifespan of females that cared for larvae until they dispersed, either when widowed before hatching or when partners were present throughout the first brood.</p

Mean (+SE) brood mass at dispersal at first breeding, in relation to the duration of maternal care.

<p>Mean (+SE) brood mass at dispersal at first breeding, in relation to the duration of maternal care.</p

The relationship between the treatment and the number of dead larvae.

<p>The graph shows the mean ± SE from the raw values.</p

Parent-offspring conflict over the trade-off between offspring size and number.

<p>a) Empirical analyses reveal that selection can act differently on genes in parents and offspring in the longer term to favour a different optimal balance between offspring size and brood size. Optimal outcomes for each party are labelled: offspring ‘win’ and parents ‘win’. b) Fluctuating ecological conditions can temporarily favour one party by changing the positioning of the size-number trade-off. In some scenarios, it may be temporarily aligned closer to the offspring’s optimum (as illustrated here), in others it remains closer to the parent’s optimum. c) In some situations, ecological conditions might even impose an outcome that is closer to the offspring’s optimum and against the parent’s evolutionary interest. d) Alternatively, fluctuating ecological conditions might change the gradient of the trade-off. At one extreme (shown with the green line), caused by very high food abundance for example, it may remove any conflict over offspring size completely because the optima for parents and offspring are temporarily closely aligned. At the other extreme (shown with the red line), caused by sudden limited food availability for example, it may temporarily prevent offspring from ever attaining investment close to their optimum.</p

Mean (+SE) brood mass at dispersal at subsequent breeding bout, in relation to the duration of maternal care at first breeding.

<p>Mean (+SE) brood mass at dispersal at subsequent breeding bout, in relation to the duration of maternal care at first breeding.</p

Mean (+SE) lifespan of experimentally widowed females in relation to the time spent caring for their first brood.

<p>Mean (+SE) lifespan of experimentally widowed females in relation to the time spent caring for their first brood.</p

The relationship between the brood mass (g) and the mass of the prepared carcass (g), after removing four extreme values in the '10 mite' treatment.

<p>The graph shows the linear regression between the raw values, separated by the mite treatment.</p

The relationship between the brood mass (g) and the mass of the prepared carcass (g).

<p>The graph shows the linear regression between the raw values, separated by the mite treatment.</p

The relationship between brood mass and the different mite density treatment.

<p>Means ± SE are raw values.</p

The relationship between the change in carcass mass after its preparation and larval mass at dispersal.

<p>Only broods from the '16 mite' treatment, and with fewer than 20 larvae per brood are presented. Means ± SE are raw values.</p