Separate and combined effects of nutrition during juvenile and sexual development on female life-history trajectories: the thrifty phenotype in a cockroach

When females anticipate a hazardous environment for their offspring, they can increase offspring survival by producing larger young. Early environmental experience determines egg size in different animal taxa. We predicted that a higher perceived predation risk by juveniles would cause an increase in the sizes of eggs that they produce as adults. To test this, we exposed juveniles of the mouthbrooding cichlid Eretmodus cyanostictus in a split-brood experiment either to cues of a natural predator or to a control situation. After maturation, females that had been confronted with predators produced heavier eggs, whereas clutch size itself was not affected by the treatment. This effect cannot be explained by a differential female body size because the predator treatment did not influence growth trajectories. The observed increase of egg mass is likely to be adaptive, as heavier eggs gave rise to larger young and in fish, juvenile predation risk drops sharply with increasing body size. This study provides the first evidence that predator cues perceived by females early in life positively affect egg mass, suggesting that these cues allow her to predict the predation risk for her offspring.

Section: Discussionmentioning

confidence: 67%

Juvenile exposure to predator cues induces a larger egg size in fish

Segers

Taborsky

2011

“…Such a test requires the independent manipulation of the environment during development and in adulthood in a crossover design, which needs a level of control that usually requires a laboratory setting. There are few such experiments and these have generally failed to find such interaction effects [24][25][26][27][28] (but see [29]). However, these studies all used species with indeterminate growth and/or developmental phases of flexible duration.…”

Section: Introductionmentioning

confidence: 99%

Food availability affects adult survival trajectories depending on early developmental conditions

Briga¹,

Koetsier²,

Boonekamp³

et al. 2017

Food availability modulates survival in interaction with (for example) competition, disease and predators, but to what extent food availability in natural populations affects survival independent of these factors is not well known. We tested the effect of food availability on lifespan and actuarial senescence in a large population of captive zebra finches by increasing the effort required to obtain food, reflecting natural contrasts in food availability. Food availability may not affect all individuals equally and we therefore created heterogeneity in phenotypic quality by raising birds with different numbers of siblings. Low food availability had no effect on lifespan for individuals from benign developmental conditions (raised in small broods), but shortened lifespan for individuals from harsh developmental conditions. The lifespan difference arose through higher baseline mortality rate of individuals from harsh developmental conditions, despite a decrease in the rate of actuarial senescence. We found no evidence for sex-specific environmental sensitivity, but females lived shorter than males due to increased actuarial senescence. Thus, low food availability by itself shortens lifespan, but only in individuals from harsh developmental conditions. Our food availability manipulation resembles dietary restriction as applied to invertebrates, where it extends lifespan in model organisms and we discuss possible reasons for the contrasting results.

“…Our findings also raise general questions about the mechanisms through which carers affect phenotypes. There is abundant evidence in many systems that nutrition and hygiene during development influence an array of different phenotypic traits [45]. Other mechanisms, such as the transfer of hormones, enzymes and gut microbiota, and indirect genetic effects mediated through carers are only now being discovered and await future exploration [40,46].…”

Section: Discussionmentioning

confidence: 99%

Foster carers influence brood pathogen resistance in ants

Purcell

Chapuisat

2014

Social organisms face a high risk of epidemics, and respond to this threat by combining efficient individual and collective defences against pathogens. An intriguing and little studied feature of social animals is that individual pathogen resistance may depend not only on genetic or maternal factors, but also on the social environment during development. Here, we used a cross-fostering experiment to investigate whether the pathogen resistance of individual ant workers was shaped by their own colony of origin or by the colony of origin of their carers. The origin of care-giving workers significantly influenced the ability of newly eclosed cross-fostered Formica selysi workers to resist the fungal entomopathogen Beauveria bassiana. In particular, carers that were more resistant to the fungal entomopathogen reared more resistant workers. This effect occurred in the absence of post-infection social interactions, such as trophallaxis and allogrooming. The colony of origin of eggs significantly influenced the survival of the resulting individuals in both control and pathogen treatments. There was no significant effect of the social organization (i.e. whether colonies contain a single or multiple queens) of the colony of origin of either carers or eggs. Our experiment reveals that social interactions during development play a central role in moulding the resistance of emerging workers.