Rebecca Kilner

Parental care results in a greater mutation load, for which it is also a phenotypic antidote

Publisher: The Royal Society

Date: 24-05-2023

DOI: 10.1098/RSPB.2023.0115

Abstract: Benevolent social behaviours, such as parental care, are thought to enable mildly deleterious mutations to persist. We tested this prediction experimentally using the burying beetle Nicrophorus vespilloides , an insect with biparental care. For 20 generations, we allowed replicate experimental burying beetle populations to evolve either with post-hatching care (‘Full Care’ populations) or without it (‘No Care’ populations). We then established new lineages, seeded from these experimental populations, which we inbred to assess their mutation load. Outbred lineages served as controls. We also tested whether the deleterious effects of a greater mutation load could be concealed by parental care by allowing half the lineages to receive post-hatching care, while half did not. We found that inbred lineages from the Full Care populations went extinct more quickly than inbred lineages from the No Care populations—but only when offspring received no post-hatching care. We infer that Full Care lineages carried a greater mutation load, but that the associated deleterious effects on fitness could be overcome if larvae received parental care. We suggest that the increased mutation load caused by parental care increases a population's dependence upon care. This could explain why care is seldom lost once it has evolved.

Parental effects alter the adaptive value of an adult behavioural trait

Publisher: eLife Sciences Publications, Ltd

Date: 22-09-2015

DOI: 10.7554/ELIFE.07340

Abstract: The parents' phenotype, or the environment they create for their young, can have long-lasting effects on their offspring, with profound evolutionary consequences. Yet, virtually no work has considered how such parental effects might change the adaptive value of behavioural traits expressed by offspring upon reaching adulthood. To address this problem, we combined experiments on burying beetles (Nicrophorus vespilloides) with theoretical modelling and focussed on one adult behavioural trait in particular: the supply of parental care. We manipulated the early-life environment and measured the fitness payoffs associated with the supply of parental care when larvae reached maturity. We found that (1) adults that received low levels of care as larvae were less successful at raising larger broods and suffered greater mortality as a result: they were low-quality parents. Furthermore, (2) high-quality males that raised offspring with low-quality females subsequently suffered greater mortality than brothers of equivalent quality, which reared larvae with higher quality females. Our analyses identify three general ways in which parental effects can change the adaptive value of an adult behavioural trait: by influencing the associated fitness benefits and costs by consequently changing the evolutionary outcome of social interactions and by modifying the evolutionarily stable expression of behavioural traits that are themselves parental effects.

Brood parasitism and the evolution of cooperative breeding in birds

Publisher: American Association for the Advancement of Science (AAAS)

Date: 20-12-2013

DOI: 10.1126/SCIENCE.1240039

Abstract: Avian brood parasites target particular bird species to raise their offspring, sometimes at great cost to the foster family. Feeney et al. (p. 1506 see the Perspective by Spottiswoode ) analyzed the global distribution of brood parasitism and found a correlation with the occurrence of cooperative breeders across multiple taxa. For ex le, Australian fairy wrens breed both singly and in cooperative groups, but the group breeders are better able to resist parasites than lone pairs, indicating that the prevalence of cooperative breeding may be a response to brood parasites.

Egg size investment in superb fairy-wrens: helper effects are modulated by climate.

Publisher: The Royal Society

Date: 30-11-2016

DOI: 10.1098/RSPB.2016.1875

Abstract: Natural populations might exhibit resilience to changing climatic conditions if they already show adaptive flexibility in their reproductive strategies. In cooperative breeders, theory predicts that mothers with helpers should provide less care when environmental conditions are favourable, but maintain high investment when conditions are challenging. Here, we test for evidence of climate-mediated flexibility in maternal investment in the cooperatively breeding superb fairy-wren Malurus cyaneus . We focus on egg size because in this species egg size influences offspring size, and females reduce egg investment when there are helpers at the nest. We report that females lay larger eggs during dry, hot conditions. However, the effect of temperature is modulated by the presence of helpers: the average egg size of females with helpers is reduced during cooler conditions but increased during hot conditions relative to females without helpers. This appears to reflect plasticity in egg investment rather than among female differences. Analysis of maternal survival suggests that helped females are better able to withstand the costs of breeding in hot conditions than females without helpers. Our study suggests that females can use multiple, independent cues to modulate egg investment flexibly in a variable environment.

Prenatal environmental effects match offspring begging to parental provisioning

Publisher: The Royal Society

Date: 06-05-2009

DOI: 10.1098/RSPB.2009.0375

Abstract: The solicitation behaviours performed by dependent young are under selection from the environment created by their parents, as well as wider ecological conditions. Here we show how mechanisms acting before hatching enable canary offspring to adapt their begging behaviour to a variable post-hatching world. Cross-fostering experiments revealed that canary nestling begging intensity is positively correlated with the provisioning level of their own parents (to foster chicks). When we experimentally increased food quality before and during egg laying, mothers showed higher faecal androgen levels and so did their nestlings, even when they were cross-fostered before hatching to be reared by foster mothers that had been exposed to a standard regime of food quality. Higher parental androgen levels were correlated with greater levels of post-hatching parental provisioning and (we have previously shown) increased faecal androgens in chicks were associated with greater begging intensity. We conclude that androgens mediate environmentally induced plasticity in the expression of both parental and offspring traits, which remain correlated as a result of prenatal effects, probably acting within the egg. Offspring can thus adapt their begging intensity to variable family and ecological environments.

Visual mimicry of host nestlings by cuckoos

Publisher: The Royal Society

Date: 12-01-2011

DOI: 10.1098/RSPB.2010.2391

Abstract: Coevolution between antagonistic species has produced instances of exquisite mimicry. Among brood-parasitic cuckoos, host defences have driven the evolution of mimetic eggs, but the evolutionary arms race was believed to be constrained from progressing to the chick stage, with cuckoo nestlings generally looking unlike host young. However, recent studies on bronze-cuckoos have confounded theoretical expectations by demonstrating cuckoo nestling rejection by hosts. Coevolutionary theory predicts reciprocal selection for visual mimicry of host young by cuckoos, although this has not been demonstrated previously. Here we show that, in the eyes of hosts, nestlings of three bronze-cuckoo species are striking visual mimics of the young of their morphologically erse hosts, providing the first evidence that coevolution can select for visual mimicry of hosts in cuckoo chicks. Bronze-cuckoos resemble their own hosts more closely than other host species, but the accuracy of mimicry varies according to the ersity of hosts they exploit.

Parental care results in a greater mutation load, for which it is also a phenotypic antidote

Publisher: Cold Spring Harbor Laboratory

Date: 05-05-2022

DOI: 10.1101/2022.05.05.490718

Abstract: Benevolent social behaviours, such as parental care, are thought to enable mildly deleterious mutations to persist. We tested this prediction experimentally using the burying beetle Nicrophorus vespilloides , an insect with biparental care. For 20 generations, we allowed replicate experimental burying beetle populations to evolve either with post-hatching care (‘Full Care’ populations) or without it (‘No Care’ populations). We then established new lineages, seeded from these experimental populations, which we inbred to assess their mutation load. Outbred lineages served as controls. We also tested whether the deleterious effects of a greater mutation load could be concealed by parental care by allowing half the lineages to receive post-hatching care, while half did not. We found that inbred lineages from the Full Care populations went extinct more quickly than inbred lineages from the No Care populations – but only when offspring received no post-hatching care. We infer that Full Care lineages carried a greater mutation load, but that the associated deleterious effects on fitness could be overcome if larvae received parental care. We suggest that the increased mutation load caused by parental care increases a population’s dependence upon care. This could explain why care is seldom lost once it has evolved.

Foraging for carotenoids: do colorful male hihi target carotenoid-rich foods in the wild?

Publisher: Oxford University Press (OUP)

Date: 2014

DOI: 10.1093/BEHECO/ARU076

Maternal investment tactics in superb fairy-wrens

Publisher: The Royal Society

Date: 24-10-2008

DOI: 10.1098/RSPB.2007.0821

Abstract: In cooperatively breeding species, parents often use helper contributions to offspring care to cut their own costs of investment (i.e. load-lightening). Understanding the process of load-lightening is essential to understanding both the rules governing parental investment and the adaptive value of helping behaviour, but little experimental work has been conducted. Here we report the results of field experiments to determine maternal provisioning rules in cooperatively breeding superb fairy-wrens ( Malurus cyaneus ). By manipulating carer : offspring ratios, we demonstrate that helpers allow females to reduce the rate at which they provision their brood. Female reductions, however, were less than that provided by helpers, so that chicks still received food at a faster rate in the presence of helpers. Despite this, chicks fed by parents and helpers were not heavier than those provisioned by parents alone. This is because maternal load-lightening not only occurs during the chick provisioning stage, but also at the egg investment stage. Theoretically, complete load-lightening is predicted when parents value themselves more highly than their offspring. We tested this idea by ‘presenting’ mothers with a ‘choice’ between reducing their own levels of care and increasing investment in their offspring. We found that mothers preferred to cut their contributions to brood care, just as predicted. Our experiments help to explain why helper effects on offspring success have been difficult to detect in superb fairy-wrens, and suggest that the accuracy with which theoretical predictions of parental provisioning rules are matched in cooperative birds depends on measuring maternal responses to helper presence at both the egg and chick stages.

Does testosterone mediate the trade-off between nestling begging and growth in the canary (Serinus canaria)?

Publisher: Elsevier BV

Date: 12-2007

DOI: 10.1016/J.YHBEH.2007.08.009

Abstract: Nestling birds solicit food from their parents with vigorous begging displays, involving posturing, jostling and calling. In some species, such as canaries, begging is especially costly because it causes a trade off against nestling growth. Fitness costs of begging like this are predicted by evolutionary theory because they function to resolve conflicts of interest within the family over the provision of parental investment. However, the mechanism that links these costs with nestling behaviour remains unclear. In the present study, we determine if the relationships between nestling androgen levels, nestling begging intensities and nestling growth rates are consistent with the hypothesis that testosterone is responsible for the trade-off between begging and growth. We test this idea with a correlational study, using fecal androgens as a non-invasive method for assaying nestling androgen levels. Our results show that fecal androgen levels are positively correlated with nestling begging intensity, and reveal marked family differences in each trait. Furthermore, changes in fecal androgen levels between 5 and 8 days after hatching are positively associated with changes in nestling begging intensity, and negatively associated with nestling growth during this time. Although these correlational results support our predictions, we suggest that that experimental manipulations are now required to test the direct or indirect role of testosterone in mediating the trade-off between begging and growth.

“Jack-of-all-trades” egg mimicry in the brood parasitic Horsfield’s bronze-cuckoo?

Publisher: Oxford University Press (OUP)

Date: 2014

DOI: 10.1093/BEHECO/ARU133

The evolution of egg rejection by cuckoo hosts in Australia and Europe

Publisher: Oxford University Press (OUP)

Date: 13-04-2005

DOI: 10.1093/BEHECO/ARI041

Giving hihi a helping hand: assessment of alternative rearing diets in food supplemented populations of an endangered bird

Publisher: Wiley

Date: 31-01-2013

DOI: 10.1111/ACV.12026

Pembroke College, University Of Cambridge

Location: United Kingdom of Great Britain and Northern Ireland

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University Of Oxford

Location: United Kingdom of Great Britain and Northern Ireland

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University Of Cambridge

Location: United Kingdom of Great Britain and Northern Ireland

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Magdalene College, University Of Cambridge

Location: United Kingdom of Great Britain and Northern Ireland

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University Of Cambridge Sidney Sussex College

Location: United Kingdom of Great Britain and Northern Ireland

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University Of Cambridge

Location: No location found

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Magdalene College, University Of Cambridge

Location: No location found

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Discovery Projects - Grant ID: DP0450188

Start Date: 08-2004

End Date: 12-2010

Amount: $475,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP110101966

Start Date: 05-2011

End Date: 12-2016

Amount: $440,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP180100021

Start Date: 06-2018

End Date: 05-2023

Amount: $424,192.00

Funder: Australian Research Council