Ladybird mothers mitigate offspring starvation risk by laying trophic eggs

While conventional wisdom holds that excessive body weight is the product of some combination of a high-calorie diet and a sedentary lifestyle, public health measures aimed at these factors have been met with only limited success. This chapter considers the possibility that obesity might be better understood in terms of the biologist's notion that humans and other animals evolved the ability to store body fat as an optimal response to the presence of starvation risk. Evidence from a broad array of disciplines is consistent with this view, including the neuroendocrinology of energy homeostasis, parallels between human and animal fattening behaviour, the effect of stress on dietary intake, population-level studies of the impact of economic insecurity on body weight and international variation in obesity rates.

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Managing uncertainty: information and insurance under the risk of starvation

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2002.1061 ◽

2002 ◽

Vol 357 (1427) ◽

pp. 1519-1526 ◽

Cited By ~ 70

Author(s):

Sasha R. X. Dall ◽

Rufus A. Johnstone

Keyword(s):

Value Of Information ◽

Food Sources ◽

Initial Increase ◽

Energy Reserves ◽

Relative Value ◽

Uncertainty Information ◽

Starvation Risk ◽

Overall Risk

In an uncertain world, animals face both unexpected opportunities and danger. Such outcomes can select for two potential strategies: collecting information to reduce uncertainty, or insuring against it. We investigate the relative value of information and insurance (energy reserves) under starvation risk by offering model foragers a choice between constant and varying food sources over finite foraging bouts. We show that sampling the variable option (choosing it when it is not expected to be good) should decline both with lower reserves and late in foraging bouts; in order to be able to reap the reduction in uncertainty associated with exploiting a variable resource effectively, foragers must be able to afford and compensate for an initial increase in the risk of an energetic shortfall associated with choosing the option when it is bad. Consequently, expected exploitation of the varying option increases as it becomes less variable, and when the overall risk of energetic shortfall is reduced. In addition, little activity on the variable alternative is expected until reserves are built up early in a foraging bout. This indicates that gathering information is a luxury while insurance is a necessity, at least when foraging on stochastic and variable food under the risk of starvation.

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Personality predicts individual responsiveness to the risks of starvation and predation

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2011.2227 ◽

2011 ◽

Vol 279 (1735) ◽

pp. 1919-1926 ◽

Cited By ~ 70

Author(s):

J. L. Quinn ◽

E. F. Cole ◽

J. Bates ◽

R. W. Payne ◽

W. Cresswell

Keyword(s):

Life Histories ◽

Parus Major ◽

Poor Quality ◽

Trade Off ◽

Quality Food ◽

Individual Personality ◽

Temporal And Spatial ◽

Time Spent Feeding ◽

Individual Responsiveness ◽

Starvation Risk

Theory suggests that individual personality is tightly linked to individual life histories and to environmental variation. The reactive–proactive axis, for example, is thought to reflect whether individuals prioritize productivity or survival, mutually exclusive options that can be caused by conflicts between foraging and anti-predation behaviour. Evidence for this trade-off hypothesis, however, is limited. Here, we tested experimentally whether exploration behaviour (EB), an assay of proactivity, could explain how great tits ( Parus major ) respond to changes in starvation and predation risk. Individuals were presented with two feeders, holding good or poor quality food, which interchanged between safe and dangerous positions 10 m apart, across two 24 h treatments. Starvation risk was assumed to be highest in the morning and lowest in the afternoon. The proportion of time spent feeding on good quality food (PTG) rather than poor quality food was repeatable within treatments, but individuals varied in how PTG changed with respect to predation- and starvation-risk across treatments. This individual plasticity variation in foraging behaviour was linked to EB, as predicted by the reactive–proactive axis, but only among individuals in dominant social classes. Our results support the trade-off hypothesis at the level of individuals in a wild population, and suggest that fine-scale temporal and spatial variation may play important roles in the evolution of personality.

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Reproductive constraint is a developmental mechanism that maintains social harmony in advanced ant societies

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.0807351105 ◽

2008 ◽

Vol 105 (46) ◽

pp. 17884-17889 ◽

Cited By ~ 60

Author(s):

Abderrahman Khila ◽

Ehab Abouheif

Keyword(s):

Molecular Mechanisms ◽

Worker Reproduction ◽

Developmental Genetic ◽

Potential Conflict ◽

Trophic Eggs ◽

Maternal Determinants ◽

Colony Efficiency ◽

Reproductive Division Of Labor ◽

Reproductive Division ◽

Colony Level

A hallmark of eusociality in ants is the reproductive division of labor between queens and workers. Yet, nothing is known about the molecular mechanisms underlying reproduction in this group. We therefore compared the developmental genetic capacity of queens and workers to reproduce in several eusocially advanced species from the two largest subfamilies of ants, the Myrmicinae and Formicinae. In flies, the asymmetric localization of maternally encoded determinants (mRNAs and proteins) during oogenesis establishes oocyte polarity and subsequently ensures proper embryonic development. Vasa and nanos, two key maternal determinants, are properly localized in the posterior of queen oocytes, but their localization is impaired in those of the workers. This mislocalization leads to severe embryonic defects in worker progeny, and therefore, represents a constraint on worker reproduction that we call ‘reproductive constraint.’ We show that reproductive constraint is phylogenetically widespread, and is at high levels in most species tested. Reproductive constraint can simultaneously reduce or eliminate the workers' ability to produce viable eggs for reproduction, while preserving their ability to produce trophic eggs for nutrition, and thus, may have been the basis for the evolutionary retention of worker ovaries in the majority of ants. We propose that high levels of reproductive constraint has most likely evolved as a consequence of selection at the colony level to reduce or eliminate any potential conflict over worker reproduction, therefore maintaining harmony and colony efficiency in advanced ant societies.

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Trophic eggs laid by fertileMyrmica queens (Hymenoptera: Formicidae)

Insectes Sociaux ◽

10.1007/bf01240424 ◽

1995 ◽

Vol 42 (3) ◽

pp. 303-308 ◽

Cited By ~ 4

Author(s):

J. C. Wardlaw ◽

G. W. Elmes

Keyword(s):

Trophic Eggs

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Trophic eggs compensate for poor offspring feeding capacity in a subsocial burrower bug

Biology Letters ◽

10.1098/rsbl.2010.0707 ◽

2010 ◽

Vol 7 (2) ◽

pp. 194-196 ◽

Cited By ~ 11

Author(s):

Narumi Baba ◽

Mantaro Hironaka ◽

Takahiro Hosokawa ◽

Hiromi Mukai ◽

Shintaro Nomakuchi ◽

...

Keyword(s):

Maternal Investment ◽

Evolutionary Origin ◽

Intact Seed ◽

Physiological Constraints ◽

First Instar ◽

Important Constraint ◽

Trophic Eggs ◽

Almost All

Various animals produce inviable eggs or egg-like structures called trophic eggs, which are presumed to be an extended maternal investment for the offspring. However, there is little knowledge about the ecological or physiological constraints associated with their evolutionary origin. Trophic eggs of the seminivorous subsocial burrower bug ( Canthophorus niveimarginatus ) have some unique characteristics. Trophic eggs are obligate for nymphal survival, and first-instar nymphs die without them. To identify the cause of nymphal death, we hypothesized that first-instar nymphs starve to death because they cannot feed on anything but trophic eggs. Although first-instar nymphs fed on artificially exposed endosperm did survive, nymphs that were provided with intact seed were not able to penetrate the seed vessel and starved to death. Another hypothesis that trophic eggs play a role in transferring the midgut symbiont, essential for survival in heteropteran bugs, from mother to offspring was rejected because almost all nymphs had retained the symbiont without feeding on trophic eggs. These results suggest that poor feeding capacity of the offspring is the cause of nymphal death, and the important constraint that promotes the evolution of the curious trophic egg system in C. niveimarginatus .

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Mass-dependent predation risk and lethal dolphin–porpoise interactions

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2007.0786 ◽

2007 ◽

Vol 274 (1625) ◽

pp. 2587-2593 ◽

Cited By ~ 33

Author(s):

R MacLeod ◽

C.D MacLeod ◽

J.A Learmonth ◽

P.D Jepson ◽

R.J Reid ◽

...

Keyword(s):

Predation Risk ◽

Bottlenose Dolphins ◽

Flight Performance ◽

Energy Reserves ◽

Trade Off ◽

Fat Reserves ◽

Ecological Principle ◽

Mass Dependent ◽

Starvation Risk ◽

Individual Mass

In small birds, mass-dependent predation risk (MDPR) is known to make the trade-off between avoiding starvation and avoiding predation dependent on individual mass. This occurs because carrying increased fat reserves not only reduces starvation risk but also results in a higher predation risk due to reduced escape flight performance and/or the increased foraging exposure needed to maintain a higher body mass. In principle, the theory of MDPR could also apply to any animal capable of storing energy reserves to reduce starvation and whose escape performance decreases with increasing mass. We used a unique situation along certain parts of coastal Britain, where harbour porpoises ( Phocoena phocoena ) are pursued and killed but crucially not eaten by bottlenose dolphins ( Tursiops truncatus ), to investigate whether a MDPR effect can occur in non-avian species. We show that where high levels of dolphin ‘predation’ occur, porpoises carry significantly less energy reserves than would otherwise be expected and this equates to reducing by approximately 37% the length of time that a porpoise could survive without feeding. These results provide the first evidence that a mass-dependent starvation–predation risk trade-off may be a general ecological principle that can apply to widely different animal types rather than, as is currently thought, only to birds.

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