Publications by year
In Press
Royle NJ, Smiseth PT, Kölliker M (eds)(In Press).
The Evolution of Parental Care., Oxford University Press.
Abstract:
The Evolution of Parental Care
Abstract.
2023
Downing BC, Silk MJ, Delahay RJ, Bearhop S, Royle NJ (2023). Culling‐induced perturbation of social networks of wild geese reinforces rather than disrupts associations among survivors.
Journal of Applied EcologyAbstract:
Culling‐induced perturbation of social networks of wild geese reinforces rather than disrupts associations among survivors
Abstract
Wildlife populations may be the subject of management interventions for disease control that can have unintended, counterproductive effects. Social structure exerts a strong influence over infectious disease transmission in addition to other characteristics of populations such as size and density that are the primary target for disease control. Social network approaches have been widely used to understand disease transmission in wildlife but rarely in the context of perturbations, such as culling, despite the likely impacts of such disturbance on social structure and disease dynamics.
Here we present a ‘removal’ study of a free‐living population of resident Canada geese Branta canadensis, a highly social species that is frequently managed by culling and can carry pathogens relevant to human and domestic animal health. We quantified social network structure and spatial behaviour before and after controlled culling of individuals during the summer moult.
Culling did not substantially increase individual social connectivity. Individuals that moulted at cull sites or were formerly strongly associated with removed birds were more likely to strengthen and maintain any surviving existing associations while also forming new associations. However, the establishment of new associations was largely compensatory (with only small increases in the number and strength of connections) and occurred locally.
Synthesis and applications: Geese that survived the cull responded by strengthening existing social relationships and forming new, compensatory relationships with birds local to them in the network. In the short term, such compensatory adjustments to patterns of association in response to culling could facilitate pathogen transmission. But in the longer term, controlled culling of geese is unlikely to strongly influence pathogen spread and may even slow transmission into new social clusters by reducing wider mixing. When managing wildlife for disease control, in addition to changes in social network structure the prevalence of infection at the time of the cull and the mode of transmission (e.g. direct vs. environmental) will also be critical determinants of disease transmission risk in perturbed populations of geese and other wild animals.
Abstract.
2020
Houslay TM, Kitchener PA, Royle NJ (2020). Are older parents less flexible? Testing age-dependent plasticity in Nicrophorus vespilloides burying beetles. Animal Behaviour, 162, 79-86.
2019
Royle N, Houslay T, Kitchener P (2019). Houslay et al_Age-dependent plasticity_Animal Behaviour.
Carter MJ, Wilson AJ, Moore AJ, Royle NJ (2019). The role of indirect genetic effects in the evolution of interacting reproductive behaviors in the burying beetle, Nicrophorus vespilloides.
Ecology and Evolution,
9(3), 998-1009.
Abstract:
The role of indirect genetic effects in the evolution of interacting reproductive behaviors in the burying beetle, Nicrophorus vespilloides
Social interactions can give rise to indirect genetic effects (IGEs), which occur when genes expressed in one individual affect the phenotype of another individual. The evolutionary dynamics of traits can be altered when there are IGEs. Sex often involves indirect effects arising from first-order (current) or second-order (prior) social interactions, yet IGEs are infrequently quantified for reproductive behaviors. Here, we use experimental populations of burying beetles that have experienced bidirectional selection on mating rate to test for social plasticity and IGEs associated with focal males mating with a female either without (first-order effect) or with (second-order effect) prior exposure to a competitor, and resource defense behavior (first-order effect). Additive IGEs were detected for mating rate arising from (first-order) interactions with females. For resource defense behavior, a standard variance partitioning analysis provided no evidence of additive genetic variance—either direct or indirect. However, behavior was predicted by focal size relative to that of the competitor, and size is also heritable. Assuming that behavior is causally dependent on relative size, this implies that both DGEs and IGEs do occur (and may potentially interact). The relative contribution of IGEs may differ among social behaviors related to mating which has consequences for the evolutionary trajectories of multivariate traits.
Abstract.
2018
Smiseth PT, Royle NJ (2018). The resolution of conflict in families.
Current Opinion in Insect Science,
28, 8-12.
Abstract:
The resolution of conflict in families
The emergence of family groups is associated with conflict over the allocation of food or other limited resources. Understanding the mechanisms mediating the resolution of such conflict is a major aim in behavioral ecology. Most empirical work on familial conflict has focused on birds. Here, we highlight how recent work on insects provides new and exciting insights into how such conflict is resolved. This work shows that conflict resolution can be more complex than traditionally envisioned, often involving multiple mechanisms. For example, it shows that the resolution of sexual conflict involves a combination of behavioral negotiation, direct assessment of partner's state, and manipulation using anti-aphrodisiacs or prenatal maternal effects. Furthermore, it highlights that there is a shift from the traditional emphasis on conflict (and competition) to a greater emphasis on the balance between conflict on the one hand and cooperation on the other.
Abstract.
2017
Royle NJ, Hopwood PE (2017). Covetable Corpses and Plastic Beetles—The Socioecological Behavior of Burying Beetles.
Advances in the Study of Behavior,
49, 101-146.
Abstract:
Covetable Corpses and Plastic Beetles—The Socioecological Behavior of Burying Beetles
Among-individual variation in behavioral plasticity—the modification of behavior in response to changes in environment experienced by individuals—is increasingly recognized as an important, but relatively poorly understood, feature of organisms that facilitates adaptation to environmental change. It is expected to evolve when there is rapidly fluctuating or directional environmental change during the lifetime of individuals. This is particularly likely to occur in the context of reproductive behaviors, when the outcomes of unpredictable social interactions with other individuals during mating and parental care determine how selection acts on males and females and mating systems evolve. To better understand patterns of mating and parental care and organismal adaptation to environmental change, we need to know why there is so much variation in behavioral plasticity between and within species. Here we address this question using burying beetles as a model. Burying beetles have unusually variable, facultatively expressed, modes of parental care and variation between the sexes and among individuals in the plasticity of reproductive behaviors. We present evidence to show that variation in male plasticity of mating behavior is a key driver of the evolution of patterns of parental care in Nicrophorus vespilloides burying beetles. More generally, we conclude that behavioral plasticity in burying beetles, and likely other taxa, has evolved as a consequence of a resource requirement bottle-neck (niche specialization) in combination with highly unpredictable availability of such suitable resources and the social unpredictability that arises as a result: constraint is the mother of plastic invention.
Abstract.
Griffith SC, Crino OL, Andrew SC, Nomano FY, Adkins-Regan E, Alonso-Alvarez C, Bailey IE, Bittner SS, Bolton PE, Boner W, et al (2017). Variation in Reproductive Success Across Captive Populations: Methodological Differences, Potential Biases and Opportunities.
Ethology,
123(1), 1-29.
Abstract:
Variation in Reproductive Success Across Captive Populations: Methodological Differences, Potential Biases and Opportunities
Our understanding of fundamental organismal biology has been disproportionately influenced by studies of a relatively small number of ‘model’ species extensively studied in captivity. Laboratory populations of model species are commonly subject to a number of forms of past and current selection that may affect experimental outcomes. Here, we examine these processes and their outcomes in one of the most widely used vertebrate species in the laboratory – the zebra finch (Taeniopygia guttata). This important model species is used for research across a broad range of fields, partly due to the ease with which it can be bred in captivity. However despite this perceived amenability, we demonstrate extensive variation in the success with which different laboratories and studies bred their subjects, and overall only 64% of all females that were given the opportunity, bred successfully in the laboratory. We identify and review several environmental, husbandry, life-history and behavioural factors that potentially contribute to this variation. The variation in reproductive success across individuals could lead to biases in experimental outcomes and drive some of the heterogeneity in research outcomes across studies. The zebra finch remains an excellent captive animal system and our aim is to sharpen the insight that future studies of this species can provide, both to our understanding of this species and also with respect to the reproduction of captive animals more widely. We hope to improve systematic reporting methods and that further investigation of the issues we raise will lead both to advances in our fundamental understanding of avian reproduction as well as to improvements in future welfare and experimental efficiency.
Abstract.
2016
Royle NJ, Alonzo SH, Moore AJ (2016). Co-evolution, conflict and complexity: what have we
learned about the evolution of parental care behaviours?. Current Opinion in Behavioral Sciences, 12, 30-36.
Royle NJ (2016). Constraints and clutch size: a comment on Paquet and Smiseth. Behavioral Ecology, 27(3), 697-698.
Hopwood PE, Mazué GPF, Carter MJ, Head ML, Moore AJ, Royle NJ (2016). Do female Nicrophorus vespilloides reduce direct costs by choosing males that mate less frequently?.
Biology Letters,
12(3).
Abstract:
Do female Nicrophorus vespilloides reduce direct costs by choosing males that mate less frequently?
Sexual conflict occurs when selection to maximize fitness in one sex does so at the expense of the other sex. In the burying beetle Nicrophorus vespilloides, repeated mating provides assurance of paternity at a direct cost to female reproductive productivity. To reduce this cost, females could choose males with low repeated mating rates or smaller, servile males. We tested this by offering females a dichotomous choice between males from lines selected for high or low mating rate. Each female was then allocated her preferred or non-preferred male to breed. Females showed no preference for males based on whether they came from lines selected for high or low mating rates. Pairs containing males from high mating rate lines copulated more often than those with low line males but there was a negative relationship between female size and number of times she mated with a non-preferred male. When females bred with their preferred male the number of offspring reared increased with female size but there was no such increase when breeding with non-preferred males. Females thus benefited from being choosy, but this was not directly attributable to avoidance of costly male repeated mating.
Abstract.
Hopwood PE, Moore AJ, Tregenza T, Royle NJ (2016). Erratum to Male burying beetles extend, not reduce, parental care duration when reproductive competition is high [J. Evol. Biol. 28: 1394-1402]. Journal of Evolutionary Biology, 29(1).
Hopwood PE, Moore AJ, Tregenza T, Royle NJ (2016). Niche variation and the maintenance of variation in body size in a burying beetle.
Ecological Entomology,
41(1), 96-104.
Abstract:
Niche variation and the maintenance of variation in body size in a burying beetle
1. In burying beetles (Nicrophorinae), body size is known to provide both a fecundity advantage (in females) and successful resource defence (in males and females). Despite this, considerable variation in body sizes is observed in natural populations. 2. A possible explanation for the maintenance of this variation, even with intra- and inter-specific resource competition, is that individuals might assort according to body size on different-sized breeding resources. 3. We tested prediction that 'bigger is always better', in the wild and in the laboratory, by experimentally manipulating combinations of available breeding-resource size (mouse carcasses) and competitor's body size in Nicrophorus vespilloides (Herbst 1783). 4. In the field, large female beetles deserted small carcasses, without breeding, more often than they did larger carcasses, but small females used carcasses indiscriminately with respect to size. In the laboratory, large beetles reared larger broods (with more offspring) on larger carcasses than small beetles, but on small carcasses small beetles had a reproductive advantage over large ones. Offspring size covaried with carcass size independently of parental body size. 5. The present combined results suggest breeding resource value depends on an individual's body size, and variation in body size is environmentally induced: maintained by differences in available carcass sizes. This produces a mechanism by which individual specialisation leads to an increase in niche variation via body size in these beetles.
Abstract.
Royle NJ (2016). Parental Care: When the Sex Has to Stop.
Current Biology,
26(11), R478-R480.
Abstract:
Parental Care: When the Sex Has to Stop
How is sexual conflict during reproduction resolved when parents collaborate to rear offspring? a new study shows that female burying beetles communicate their hormonal status to their male partners to avoid costly superfluous mating, using an anti-aphrodisiac pheromone.
Abstract.
Hopwood PE, Head ML, Jordan EJ, Carter MJ, Davey E, Moore AJ, Royle NJ (2016). Selection on an antagonistic behavioral trait can drive rapid genital coevolution in the burying beetle, Nicrophorus vespilloides.
Evolution; international journal of organic evolution,
70(6), 1180-1188.
Abstract:
Selection on an antagonistic behavioral trait can drive rapid genital coevolution in the burying beetle, Nicrophorus vespilloides.
Male and female genital morphology varies widely across many taxa, and even among populations. Disentangling potential sources of selection on genital morphology is problematic because each sex is predicted to respond to adaptations in the other due to reproductive conflicts of interest. To test how variation in this sexual conflict trait relates to variation in genital morphology we used our previously developed artificial selection lines for high and low repeated mating rates. We selected for high and low repeated mating rates using monogamous pairings to eliminate contemporaneous female choice and male-male competition. Male and female genital shape responded rapidly to selection on repeated mating rate. High and low mating rate lines diverged from control lines after only 10 generations of selection. We also detected significant patterns of male and female genital shape coevolution among selection regimes. We argue that because our selection lines differ in sexual conflict, these results support the hypothesis that sexually antagonistic coevolution can drive the rapid divergence of genital morphology. The greatest divergence in morphology corresponded with lines in which the resolution of sexual conflict over mating rate was biased in favor of male interests.
Abstract.
Hopwood PE, Moore AJ, Tregenza T, Royle NJ (2016). The effect of size and sex ratio experiences on reproductive competition in <i>Nicrophorus vespilloides</i> burying beetles in the wild.
Journal of Evolutionary Biology,
29(3), 541-550.
Abstract:
The effect of size and sex ratio experiences on reproductive competition in Nicrophorus vespilloides burying beetles in the wild
AbstractMale parents face a choice: should they invest more in caring for offspring or in attempting to mate with other females? the most profitable course depends on the intensity of competition for mates, which is likely to vary with the population sex ratio. However, the balance of pay‐offs may vary among individual males depending on their competitive prowess or attractiveness. We tested the prediction that sex ratio and size of the resource holding male provide cues regarding the level of mating competition prior to breeding and therefore influence the duration of a male's biparental caring in association with a female. Male burying beetles, Nicrophorus vespilloides were reared, post‐eclosion, in groups that differed in sex ratio. Experimental males were subsequently translocated to the wild, provided with a breeding resource (carcass) and filmed. We found no evidence that sex ratio cues prior to breeding affected future parental care behaviour but males that experienced male‐biased sex ratios took longer to attract wild mating partners. Smaller males attracted a higher proportion of females than did larger males, securing significantly more monogamous breeding associations as a result. Smaller males thus avoided competitive male–male encounters more often than larger males. This has potential benefits for their female partners who avoid both intrasexual competition and direct costs of higher mating frequency associated with competing males.
Abstract.
2015
Carter MJ, Head ML, Moore AJ, Royle NJ (2015). Behavioral plasticity and G × E of reproductive tactics in Nicrophorus vespilloides burying beetles.
Evolution,
69(4), 969-978.
Abstract:
Behavioral plasticity and G × E of reproductive tactics in Nicrophorus vespilloides burying beetles
Phenotypic plasticity is important in the evolution of traits and facilitates adaptation to rapid environmental changes. However, variation in plasticity at the individual level, and the heritable basis underlying this plasticity is rarely quantified for behavioral traits. Alternative behavioral reproductive tactics are key components of mating systems but are not often considered within a phenotypic plasticity framework (i.e. as reaction norms). Here, using lines artificially selected for repeated mating rate, we test for genetic (G × E) sources of variation in reproductive behavior of male Nicrophorus vespilloides burying beetles (including signaling behavior), as well as the role of individual body size, in responsiveness to changes in social environment. The results show that body size influences the response of individuals' signaling behavior to changes in the social environment. Moreover, there was G × E underlying the responses of males to variation in the quality of social environment experienced (relative size of focal male compared to his rival). This shows that individual variation in plasticity and social sensitivity of signaling behavior can evolve in response to selection on investment in mating behavior, with males selected for high mating investment having greater social sensitivity.
Abstract.
Carter MJ, Head ML, Moore AJ, Royle NJ (2015). Behavioral plasticity and G × E of reproductive tactics in Nicrophorus vespilloides burying beetles.
Evolution,
69(4), 969-978.
Abstract:
Behavioral plasticity and G × E of reproductive tactics in Nicrophorus vespilloides burying beetles.
Phenotypic plasticity is important in the evolution of traits and facilitates adaptation to rapid environmental changes. However, variation in plasticity at the individual level, and the heritable basis underlying this plasticity is rarely quantified for behavioral traits. Alternative behavioral reproductive tactics are key components of mating systems but are not often considered within a phenotypic plasticity framework (i.e. as reaction norms). Here, using lines artificially selected for repeated mating rate, we test for genetic (G × E) sources of variation in reproductive behavior of male Nicrophorus vespilloides burying beetles (including signaling behavior), as well as the role of individual body size, in responsiveness to changes in social environment. The results show that body size influences the response of individuals' signaling behavior to changes in the social environment. Moreover, there was G × E underlying the responses of males to variation in the quality of social environment experienced (relative size of focal male compared to his rival). This shows that individual variation in plasticity and social sensitivity of signaling behavior can evolve in response to selection on investment in mating behavior, with males selected for high mating investment having greater social sensitivity.
Abstract.
Author URL.
Royle NJ, Orledge JM, Blount JD (2015). Early Life-History Effects, Oxidative Stress, and the Evolution and Expression of Animal Signals. In (Ed)
Animal Signaling and Function: an Integrative Approach, 11-46.
Abstract:
Early Life-History Effects, Oxidative Stress, and the Evolution and Expression of Animal Signals
Abstract.
Hopwood PE, Moore AJ, Tregenza T, Royle NJ (2015). Male burying beetles extend, not reduce, parental care duration when reproductive competition is high.
J Evol Biol,
28(7), 1394-1402.
Abstract:
Male burying beetles extend, not reduce, parental care duration when reproductive competition is high.
Male parents spend less time caring than females in many species with biparental care. The traditional explanation for this pattern is that males have lower confidence of parentage, so they desert earlier in favour of pursuing other mating opportunities. However, one recent alternative hypothesis is that prolonged male parental care might also evolve if staying to care actively improves paternity. If this is the case, an increase in reproductive competition should be associated with increased paternal care. To test this prediction, we manipulated the level of reproductive competition experienced by burying beetles, Nicrophorus vespilloides (Herbst, 1783). We found that caregiving males stayed for longer and mated more frequently with their partner when reproductive competition was greater. Reproductive productivity did not increase when males extended care. Our findings provide support for the increased paternity hypothesis. Extended duration of parental care may be a male tactic both protecting investment (in the current brood) and maximizing paternity (in subsequent brood(s) via female stored sperm) even if this fails to maximize current reproductive productivity and creates conflict of interest with their mate via costs associated with increased mating frequency.
Abstract.
Author URL.
Archer CR, Hempenstall S, Royle NJ, Selman C, Willis S, Rapkin J, Blount JD, Hunt J (2015). Testing the Effects of DL-Alpha-Tocopherol Supplementation on Oxidative Damage, Total Antioxidant Protection and the Sex-Specific Responses of Reproductive Effort and Lifespan to Dietary Manipulation in Australian Field Crickets (Teleogryllus commodus).
Antioxidants (Basel),
4(4), 768-792.
Abstract:
Testing the Effects of DL-Alpha-Tocopherol Supplementation on Oxidative Damage, Total Antioxidant Protection and the Sex-Specific Responses of Reproductive Effort and Lifespan to Dietary Manipulation in Australian Field Crickets (Teleogryllus commodus).
The oxidative stress theory predicts that the accumulation of oxidative damage causes aging. More generally, oxidative damage could be a cost of reproduction that reduces survival. Both of these hypotheses have mixed empirical support. To better understand the life-history consequences of oxidative damage, we fed male and female Australian field crickets (Teleogryllus commodus) four diets differing in their protein and carbohydrate content, which have sex-specific effects on reproductive effort and lifespan. We supplemented half of these crickets with the vitamin E isoform DL-alpha-tocopherol and measured the effects of nutrient intake on lifespan, reproduction, oxidative damage and antioxidant protection. We found a clear trade-off between reproductive effort and lifespan in females but not in males. In direct contrast to the oxidative stress theory, crickets fed diets that improved their lifespan had high levels of oxidative damage to proteins. Supplementation with DL-alpha-tocopherol did not significantly improve lifespan or reproductive effort. However, males fed diets that increased their reproductive investment experienced high oxidative damage to proteins. While this suggests that male reproductive effort could elevate oxidative damage, this was not associated with reduced male survival. Overall, these results provide little evidence that oxidative damage plays a central role in mediating life-history trade-offs in T. commodus.
Abstract.
Author URL.
2014
Head ML, Hinde CA, Moore AJ, Royle NJ (2014). Correlated evolution in parental care in females but not males in response to selection on paternity assurance behaviour.
Ecology Letters,
17(7), 803-810.
Abstract:
Correlated evolution in parental care in females but not males in response to selection on paternity assurance behaviour
According to classical parental care theory males are expected to provide less parental care when offspring in a brood are less likely to be their own, but empirical evidence in support of this relationship is equivocal. Recent work predicts that social interactions between the sexes can modify co-evolution between traits involved in mating and parental care as a result of costs associated with these social interactions (i.e. sexual conflict). In burying beetles (Nicrophorus vespilloides), we use artificial selection on a paternity assurance trait, and crosses within and between selection lines, to show that selection acting on females, not males, can drive the co-evolution of paternity assurance traits and parental care. Males do not care more in response to selection on mating rate. Instead, patterns of parental care change as an indirect response to costs of mating for females. © 2014 the Authors. Ecology Letters published by John Wiley & Sons Ltd and CNRS.
Abstract.
Head ML, Hinde CA, Moore AJ, Royle NJ (2014). Correlated evolution in parental care in females but not males in response to selection on paternity assurance behaviour.
Ecol Lett,
17(7), 803-810.
Abstract:
Correlated evolution in parental care in females but not males in response to selection on paternity assurance behaviour.
According to classical parental care theory males are expected to provide less parental care when offspring in a brood are less likely to be their own, but empirical evidence in support of this relationship is equivocal. Recent work predicts that social interactions between the sexes can modify co-evolution between traits involved in mating and parental care as a result of costs associated with these social interactions (i.e. sexual conflict). In burying beetles (Nicrophorus vespilloides), we use artificial selection on a paternity assurance trait, and crosses within and between selection lines, to show that selection acting on females, not males, can drive the co-evolution of paternity assurance traits and parental care. Males do not care more in response to selection on mating rate. Instead, patterns of parental care change as an indirect response to costs of mating for females.
Abstract.
Author URL.
Lee VE, Head ML, Carter MJ, Royle NJ (2014). Effects of age and experience on contest behavior in the burying beetle, Nicrophorus vespilloides.
Behav Ecol,
25(1), 172-179.
Abstract:
Effects of age and experience on contest behavior in the burying beetle, Nicrophorus vespilloides.
Contest behavior forms an important part of reproductive investment. Life-history theory predicts that as individuals age and their residual reproductive value decreases, they should increase investment in contest behavior. However, other factors such as social experience may also be important in determining age-related variation in contest behavior. To understand how selection acts on contest behavior over an individual's lifetime, it is therefore important to tease apart the effects of age per se from other factors that may vary with age. Here, we independently manipulate male age and social experience to examine their effects on male contest behavior in the burying beetle Nicrophorus vespilloides. We found that social experience, but not age, influenced male contest behavior but that these changes in behavior did not alter contest outcomes. Male size (relative to his opponent) was overwhelmingly the most important factor determining contest outcome. Our results suggest that in systems with high variation in fighting ability among males, there may be little opportunity for selection to act on factors that influence contest outcomes by altering motivation to win.
Abstract.
Author URL.
Hopwood PE, Moore AJ, Royle NJ (2014). Effects of resource variation during early life and adult social environment on contest outcomes in burying beetles: a context-dependent silver spoon strategy?.
Proc Biol Sci,
281(1785).
Abstract:
Effects of resource variation during early life and adult social environment on contest outcomes in burying beetles: a context-dependent silver spoon strategy?
Good early nutritional conditions may confer a lasting fitness advantage over individuals suffering poor early conditions (a 'silver spoon' effect). Alternatively, if early conditions predict the likely adult environment, adaptive plastic responses might maximize individual performance when developmental and adult conditions match (environmental-matching effect). Here, we test for silver spoon and environmental-matching effects by manipulating the early nutritional environment of Nicrophorus vespilloides burying beetles. We manipulated nutrition during two specific early developmental windows: the larval environment and the post-eclosion environment. We then tested contest success in relation to variation in adult social environmental quality experienced (defined according to whether contest opponents were smaller (good environment) or larger (poor environment) than the focal individual). Variation in the larval environment influenced adult body size but not contest success per se for a given adult social environment experienced (an 'indirect' silver spoon effect). Variation in post-eclosion environment affected contest success dependent on the quality of the adult environment experienced (a context-dependent 'direct' silver spoon effect). By contrast, there was no evidence for environmental-matching. The results demonstrate the importance of social environmental context in determining how variation in nutrition in early life affects success as an adult.
Abstract.
Author URL.
Hopwood PE, Moore AJ, Royle NJ (2014). Effects of resource variation during early life and adult social environment on contest outcomes in burying beetles: a context-dependent silver spoon strategy?.
Proceedings. Biological sciences / the Royal Society,
281(1785).
Abstract:
Effects of resource variation during early life and adult social environment on contest outcomes in burying beetles: a context-dependent silver spoon strategy?
Good early nutritional conditions may confer a lasting fitness advantage over individuals suffering poor early conditions (a 'silver spoon' effect). Alternatively, if early conditions predict the likely adult environment, adaptive plastic responses might maximize individual performance when developmental and adult conditions match (environmental-matching effect). Here, we test for silver spoon and environmental-matching effects by manipulating the early nutritional environment of Nicrophorus vespilloides burying beetles. We manipulated nutrition during two specific early developmental windows: the larval environment and the post-eclosion environment. We then tested contest success in relation to variation in adult social environmental quality experienced (defined according to whether contest opponents were smaller (good environment) or larger (poor environment) than the focal individual). Variation in the larval environment influenced adult body size but not contest success per se for a given adult social environment experienced (an 'indirect' silver spoon effect). Variation in post-eclosion environment affected contest success dependent on the quality of the adult environment experienced (a context-dependent 'direct' silver spoon effect). By contrast, there was no evidence for environmental-matching. The results demonstrate the importance of social environmental context in determining how variation in nutrition in early life affects success as an adult.
Abstract.
Royle NJ (2014). Everybody has a social life. Can social network analysis help us understand why not just how? Comment on Pinter-Wollman et al. Behavioral Ecology, 25(2), 256-257.
Wolf JB, Royle NJ, Hunt J (2014). Genotype-by-Environment Interactions when the Social Environment Contains Genes. In (Ed)
Genotype-by-Environment Interactions and Sexual Selection, 63-97.
Abstract:
Genotype-by-Environment Interactions when the Social Environment Contains Genes
Abstract.
Royle NJ, Russell AF, Wilson AJ (2014). The evolution of flexible parenting.
Science,
345(6198), 776-781.
Abstract:
The evolution of flexible parenting.
Parenting behaviors, such as the provisioning of food by parents to offspring, are known to be highly responsive to changes in environment. However, we currently know little about how such flexibility affects the ways in which parenting is adapted and evolves in response to environmental variation. This is because few studies quantify how individuals vary in their response to changing environments, especially social environments created by other individuals with which parents interact. Social environmental factors differ from nonsocial factors, such as food availability, because parents and offspring both contribute and respond to the social environment they experience. This interdependence leads to the coevolution of flexible behaviors involved in parenting, which could, paradoxically, constrain the ability of individuals to rapidly adapt to changes in their nonsocial environment.
Abstract.
Author URL.
2013
Harold S, Wong Y, Baguette M, Bonsall MB, Clobert J, Royle NJ, Settele J (2013). BMC Ecology image competition: the winning images.
BMC Ecol,
13Abstract:
BMC Ecology image competition: the winning images.
BMC Ecology announces the winning entries in its inaugural Ecology Image Competition, open to anyone affiliated with a research institute. The competition, which received more than 200 entries from international researchers at all career levels and a wide variety of scientific disciplines, was looking for striking visual interpretations of ecological processes. In this Editorial, our academic Section Editors and guest judge Dr Yan Wong explain what they found most appealing about their chosen winning entries, and highlight a few of the outstanding images that didn't quite make it to the top prize.
Abstract.
Author URL.
Royle NJ, Hopwood PE, Head ML (2013). Burying beetles.
Curr Biol,
23(20), R907-R909.
Author URL.
Schuett W, Dall SRX, Wilson AJ, Royle NJ (2013). Environmental transmission of a personality trait: Foster parent exploration behaviour predicts offspring exploration behaviour in zebra finches.
Biology Letters,
9(4).
Abstract:
Environmental transmission of a personality trait: Foster parent exploration behaviour predicts offspring exploration behaviour in zebra finches
Consistent behavioural differences between individuals are common in many species and can have important effects on offspring fitness. To understand the evolution of such personality variation it is important to determine the mode of inheritance, but this has been quantified for only a few species. Here, we report results from a breeding experiment in captive zebra finches, Taeniopygia guttata, in which we cross-fostered offspring to disentangle the importance of genetic and non-genetic transmission of behaviour. Genetic and foster-parents’ exploratory type was measured in a novel environment pre-breeding and offspring exploratory type was assessed at adulthood. Offspring exploratory type was predicted by the exploratory behaviour of the foster but not the genetic parents, whereas offspring size was predicted by genetic but not foster parents’ size. Other aspects of the social environment, such as rearing regime (uni- versus biparental), hatching position, brood size, or an individual’s sex did not influence offspring exploration. Our results therefore indicate that non-genetic transmission of behaviour can play an important role in shaping animal personality variation.
Abstract.
Benowitz KM, Head ML, Williams CA, Moore AJ, Royle NJ (2013). Male age mediates reproductive investment and response to paternity assurance.
Proceedings of the Royal Society B: Biological Sciences,
280(1764).
Abstract:
Male age mediates reproductive investment and response to paternity assurance
Theory predicts that male response to reduced paternity will depend on male state and interactions between the sexes. If there is little chance of reproducing again, then males should invest heavily in current offspring, regardless of their share in paternity. We tested this by manipulating male age and paternity assurance in the burying beetle Nicrophorus vespilloides. We found older males invested more in both mating effort and parental effort than younger males. Furthermore, male age, a component of male state, mediated male response to perceived paternity. Older males provided more prenatal care, whereas younger males provided less prenatal care, when perceived paternity was low. Adjustments in male care, however, did not influence selection acting indirectly on parents, through offspring performance. This is because females adjusted their care in response to the age of their partner, providing less care when paired with older males than younger males. As a result offspring, performance did not differ between treatments. Our study shows, for the first time, that a male state variable is an important modifier of paternity-parental care trade-offs and highlights the importance of social interactions between males and females during care in determining male response to perceived paternity. © 2013 the Authors.
Abstract.
Benowitz KM, Head ML, Williams CA, Moore AJ, Royle NJ (2013). Male age mediates reproductive investment and response to paternity assurance.
Proc Biol Sci,
280(1764).
Abstract:
Male age mediates reproductive investment and response to paternity assurance.
Theory predicts that male response to reduced paternity will depend on male state and interactions between the sexes. If there is little chance of reproducing again, then males should invest heavily in current offspring, regardless of their share in paternity. We tested this by manipulating male age and paternity assurance in the burying beetle Nicrophorus vespilloides. We found older males invested more in both mating effort and parental effort than younger males. Furthermore, male age, a component of male state, mediated male response to perceived paternity. Older males provided more prenatal care, whereas younger males provided less prenatal care, when perceived paternity was low. Adjustments in male care, however, did not influence selection acting indirectly on parents, through offspring performance. This is because females adjusted their care in response to the age of their partner, providing less care when paired with older males than younger males. As a result offspring, performance did not differ between treatments. Our study shows, for the first time, that a male state variable is an important modifier of paternity-parental care trade-offs and highlights the importance of social interactions between males and females during care in determining male response to perceived paternity.
Abstract.
Author URL.
Benowitz KM, Head ML, Williams CA, Moore AJ, Royle NJ (2013). Male age mediates reproductive investment and response to paternity assurance.
Proc Biol Sci,
280(1767).
Author URL.
Hopwood PE, Moore AJ, Royle NJ (2013). Nutrition during sexual maturation affects competitive ability but not reproductive productivity in burying beetles.
Functional Ecology,
27(6), 1350-1357.
Abstract:
Nutrition during sexual maturation affects competitive ability but not reproductive productivity in burying beetles
Food availability can be unpredictable. When food becomes more abundant following a period of low food availability, developing larvae or juveniles often allocate resources preferentially towards increasing growth. This has important long-term effects on adult phenotypes and longevity. Despite the importance of strategic resource allocation during early development, few studies have examined how changes in resource availability during other windows of development affect reproductive strategies and fitness independent of growth. We manipulated food availability in a burying beetle, Nicrophorus vespilloides, during a subadult period of sexual maturation when individuals cannot increase structural size but are still undergoing reproductive maturation. In contrast to the trade-offs during larval or juvenile growth, beetles that experienced delayed feeding during reproductive maturation allocated resources preferentially towards maintaining both reproductive function and longevity. In both sexes, delayed feeding beetles were much less successful in competition for carcasses. However, delayed feeding males and females provided similar amounts of parental care and did not differ in reproductive success or longevity. These results indicate that the nutritional environment experienced during a key developmental window may be an important determinant of the expression of alternative reproductive strategies in adulthood, independent of body size. © 2013 British Ecological Society.
Abstract.
Hopwood PE, Moore AJ, Royle NJ (2013). Nutrition during sexual maturation affects competitive ability but not reproductive productivity in burying beetles. Functional Ecology
Archer CR, Sakaluk SK, Selman C, Royle NJ, Hunt J (2013). Oxidative stress and the evolution of sex differences in life span and ageing in the decorated cricket, Gryllodes sigillatus.
Evolution,
67(3), 620-634.
Abstract:
Oxidative stress and the evolution of sex differences in life span and ageing in the decorated cricket, Gryllodes sigillatus
The Free Radical Theory of Ageing (FRTA) predicts that oxidative stress, induced when levels of reactive oxygen species exceed the capacity of antioxidant defenses, causes ageing. Recently, it has also been argued that oxidative damage may mediate important life-history trade-offs. Here, we use inbred lines of the decorated cricket, Gryllodes sigillatus, to estimate the genetic (co)variance between age-dependent reproductive effort, life span, ageing, oxidative damage, and total antioxidant capacity within and between the sexes. The FRTA predicts that oxidative damage should accumulate with age and negatively correlate with life span. We find that protein oxidation is greater in the shorter lived sex (females) and negatively genetically correlated with life span in both sexes. However, oxidative damage did not accumulate with age in either sex. Previously we have shown antagonistic pleiotropy between the genes for early-life reproductive effort and ageing rate in both sexes, although this was stronger in females. In females, we find that elevated fecundity early in life is associated with greater protein oxidation later in life, which is in turn positively correlated with the rate of ageing. Our results provide mixed support for the FRTA but suggest that oxidative stress may mediate sex-specific life-history strategies in G. sigillatus. © 2012 the Author(s). Evolution © 2012 the Society for the Study of Evolution.
Abstract.
2012
Orledge JM, Blount JD, Hoodless AN, Royle NJ (2012). Antioxidant supplementation during early development reduces parasite load but does not affect sexual ornament expression in adult ring-necked pheasants.
Functional Ecology,
26(3), 688-700.
Abstract:
Antioxidant supplementation during early development reduces parasite load but does not affect sexual ornament expression in adult ring-necked pheasants
The 'parasite-mediated sexual selection' (PMSS) hypothesis predicts that exaggerated male ornamentation could provide a signal to females of a male's ability to resist parasites. Empirical tests of the PMSS have been largely equivocal, however, which may be because most have not considered the role of early life-history effects. 2.Many sexually selected traits are carotenoid-based. Allocation of dietary-derived carotenoids to sexual ornaments may trade-off with allocation to pro-inflammatory immune response and/or antioxidant functions, mediated by the oxidative status of individuals. Exposure to parasites can increase oxidative stress, so under this scenario, sexually selected traits indicate ability to resist oxidative stress rather than ability to resist parasites per se. Such life-history trade-offs, mediated by oxidative status of individuals, are particularly acute during growth and development. 3.Here, we use ring-necked pheasants, Phasianus colchicus, a strongly sexually selected species, to test whether supplementation with dietary antioxidants (vitamin E) can mitigate the effects of early exposure to parasites (the nematode, Heterakis gallinarum), via alteration of the oxidative status of individuals, and positively affect the expression of sexual ornaments at adulthood. 4.We found that vitamin E mediated the effect of early exposure to parasites on levels of oxidative damage at 8weeks of age and reduced the parasite load of individuals at adulthood as predicted. However, the expression of sexual ornaments, immune function and growth were unaffected by either early vitamin E supplementation or manipulation of parasite load. In contrast to the predictions of the PMSS hypothesis, the intensity of sexual ornament expression was not related to either parasite load or oxidative status of individuals (current or long-term). Consequently, there was no evidence that the expression of sexual ornaments provided information on the ability of males to resist infection from parasites. © 2012 the Authors. Functional Ecology © 2012 British Ecological Society.
Abstract.
Royle NJ, Pike TW, Heeb P, Richner H, Kölliker M (2012). Offspring social network structure predicts fitness in families.
Proc Biol Sci,
279(1749), 4914-4922.
Abstract:
Offspring social network structure predicts fitness in families.
Social structures such as families emerge as outcomes of behavioural interactions among individuals, and can evolve over time if families with particular types of social structures tend to leave more individuals in subsequent generations. The social behaviour of interacting individuals is typically analysed as a series of multiple dyadic (pair-wise) interactions, rather than a network of interactions among multiple individuals. However, in species where parents feed dependant young, interactions within families nearly always involve more than two individuals simultaneously. Such social networks of interactions at least partly reflect conflicts of interest over the provision of costly parental investment. Consequently, variation in family network structure reflects variation in how conflicts of interest are resolved among family members. Despite its importance in understanding the evolution of emergent properties of social organization such as family life and cooperation, nothing is currently known about how selection acts on the structure of social networks. Here, we show that the social network structure of broods of begging nestling great tits Parus major predicts fitness in families. Although selection at the level of the individual favours large nestlings, selection at the level of the kin-group primarily favours families that resolve conflicts most effectively.
Abstract.
Author URL.
Archer CR, Sakaluk SK, Selman C, Royle NJ, Hunt J (2012). Oxidative stress and the evolution of sex differences in life span and ageing in the decorated cricket, gryllodes sigillatus. Evolution
Head ML, Berry LK, Royle NJ, Moore AJ (2012). Paternal Care: Direct and Indirect Genetic Effects of Fathers on Offspring Performance.
Evolution,
66(11), 3570-3581.
Abstract:
Paternal Care: Direct and Indirect Genetic Effects of Fathers on Offspring Performance
Knowledge of how genetic effects arising from parental care influence the evolution of offspring traits comes almost exclusively from studies of maternal care. However, males provide care in some taxa, and often this care differs from females in quality or quantity. If variation in paternal care is genetically based then, like maternal care and maternal effects, paternal effects may have important consequences for the evolution of offspring traits via indirect genetic effects (IGEs). IGEs and direct-indirect genetic covariances associated with parental care can contribute substantially to total heritability and influence predictions about how traits respond to selection. It is unknown, however, if the magnitude and sign of parental effects arising from fathers are the same as those arising from mothers. We used a reciprocal cross-fostering experiment to quantify environmental and genetic effects of paternal care on offspring performance in the burying beetle, Nicrophorus vespilloides. We found that IGEs were substantial and direct-indirect genetic covariances were negative. Combined, these patterns led to low total heritabilities for offspring performance traits. Thus, under paternal care, offspring performance traits are unlikely to evolve in response to selection, and variation in these traits will be maintained in the population despite potentially strong selection on these traits. These patterns are similar to those generated by maternal care, indicating that the genetic effects of care on offspring performance are independent of the caregiver's sex. © 2012 the Author(s). Evolution © 2012 the Society for the Study of Evolution.
Abstract.
Head ML, Berry LK, Royle NJ, Moore AJ, Moore AJ (2012). Paternal care: Direct and indirect genetic effects of fathers on offspring performance.
EvolutionAbstract:
Paternal care: Direct and indirect genetic effects of fathers on offspring performance
Knowledge of how genetic effects arising from parental care influence the evolution of offspring traits comes almost exclusively from studies of maternal care. However, males provide care in some taxa, and often this care differs from females in quality or quantity. If variation in paternal care is genetically based then, like maternal care and maternal effects, paternal effects may have important consequences for the evolution of offspring traits via indirect genetic effects (IGEs). IGEs and direct-indirect genetic covariances associated with parental care can contribute substantially to total heritability and influence predictions about how traits respond to selection. It is unknown, however, if the magnitude and sign of parental effects arising from fathers are the same as those arising from mothers. We used a reciprocal cross-fostering experiment to quantify environmental and genetic effects of paternal care on offspring performance in the burying beetle, Nicrophorus vespilloides. We found that IGEs were substantial and direct-indirect genetic covariances were negative. Combined, these patterns led to low total heritabilities for offspring performance traits. Thus, under paternal care, offspring performance traits are unlikely to evolve in response to selection, and variation in these traits will be maintained in the population despite potentially strong selection on these traits. These patterns are similar to those generated by maternal care, indicating that the genetic effects of care on offspring performance are independent of the caregiver's sex. © 2012 the Author(s).
Abstract.
Archer CR, Zajitschek F, Sakaluk SK, Royle NJ, Hunt J (2012). Sexual selection affects the evolution of lifespan and ageing in the decorated cricket gryllodes sigillatus. Evolution
Archer CR, Zajitschek F, Sakaluk SK, Royle NJ, Hunt J (2012). Sexual selection affects the evolution of lifespan and ageing in the decorated cricket gryllodes sigillatus.
Evolution,
66(10), 3088-3100.
Abstract:
Sexual selection affects the evolution of lifespan and ageing in the decorated cricket gryllodes sigillatus
Recent work suggests that sexual selection can influence the evolution of ageing and lifespan by shaping the optimal timing and relative costliness of reproductive effort in the sexes. We used inbred lines of the decorated cricket, Gryllodes sigillatus, to estimate the genetic (co)variance between age-dependent reproductive effort, lifespan, and ageing within and between the sexes. Sexual selection theory predicts that males should die sooner and age more rapidly than females. However, a reversal of this pattern may be favored if reproductive effort increases with age in males but not in females. We found that male calling effort increased with age, whereas female fecundity decreased, and that males lived longer and aged more slowly than females. These divergent life-history strategies were underpinned by a positive genetic correlation between early-life reproductive effort and ageing rate in both sexes, although this relationship was stronger in females. Despite these sex differences in life-history schedules, age-dependent reproductive effort, lifespan, and ageing exhibited strong positive intersexual genetic correlations. This should, in theory, constrain the independent evolution of these traits in the sexes and may promote intralocus sexual conflict. Our study highlights the importance of sexual selection to the evolution of sex differences in ageing and lifespan in G. sigillatus. © 2012 the Author(s). Evolution © 2012 the Society for the Study of Evolution.
Abstract.
Orledge JM, ROYLE NJ, BLOUNT JD, PIKE TW, HOODLESS AN (2012). Synergistic effects of supplementation of dietary antioxidants during growth on adult phenotype in ring-necked pheasants, Phasianus colchicus.
2011
Royle N, Pike T (2011). Do you think you're sexy?.
Planet Earth(SUMMER), 6-7.
Abstract:
Do you think you're sexy?
Nick Royle and Tom Pike discuss whether animals know how attractive they are. They gathered a group of females that showed clear, unambiguous preferences for males wearing red leg rings. They then showed male birds to them under four sets of experimental conditions. First, they gave the males a red leg ring, and showed them to females on the other side of a transparent partition. When the males and females could see each other, they gave each other more attention when males were wearing their attractive red leg ring-the female gave positive feedback and the male responded by courting her more. When the males wore green leg rings they got less positive feedback and spent less time courting. But when the females did not respond to the males because they could not see the amount of time the males spend courting was not related to which ring he was wearing.
Abstract.
Teuber K, Schiller J, Jakop U, Lüpold S, Orledge JM, Blount JD, Royle NJ, Hoodless A, Müller K (2011). MALDI-TOF mass spectrometry as a simple tool to determine the phospholipid/glycolipid composition of sperm: pheasant spermatozoa as one selected example.
Anim Reprod Sci,
123(3-4), 270-278.
Abstract:
MALDI-TOF mass spectrometry as a simple tool to determine the phospholipid/glycolipid composition of sperm: pheasant spermatozoa as one selected example.
Cellular membranes are composed of highly variable lipid molecules, mainly cholesterol and phospholipids (PLs). The cholesterol moiety and the saturation degree of the fatty acyl residues of PL determine the fluidity of the membrane, which is particularly important for sperm because they have to undergo characteristic membrane-dependent processes (acrosomal exocytosis and fusion with the oocyte). Glycolipids are an essential part of the membrane surface acting as key mediators in the interactions of sperm with components of the female genital tract. Although the lipid composition of many mammalian spermatozoa has already been determined, the lipid composition of avian spermatozoa has scarcely been investigated. Using spermatozoa extracts of the ring-necked pheasant (Phasianus colchicus) as a selected example, this work demonstrates that matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI-TOF MS) is a simple and fast method to determine spermatozoal lipid compositions. The lipid compositions of pheasant spermatozoa have not yet been investigated. In addition to common membrane (primarily diacyl) PL (sphingomyelin, phosphatidylcholine, phosphatidylinositol and phosphatidylethanolamine), remarkable variation of different sulfoglycolipids (sulfogalactocerebrosides) was identified. This is in strong contrast to all other animal species investigated so far which nearly exclusively contain the sulfoglycolipid seminolipid (sulfogalactoalkylacylglycerol). We emphasize that the MALDI MS approach allows the characterization of sulfoglycolipids of sperm within a few minutes without the necessity for previous chromatographic separation.
Abstract.
Author URL.
Schuett W, Dall SRX, Royle NJ (2011). Pairs of zebra finches with similar “personalities” make better parents.
ANIM BEHAV,
81, 609-618.
Abstract:
Pairs of zebra finches with similar “personalities” make better parents
Although behavioural plasticity should be an advantage in a varying world, there is increasing evidence for widespread stable individual differences in the behaviour of animals: i.e. “personality”. Here we provide evidence suggesting that sexual selection is an important factor in the evolution of personality in species with biparental care. Using a cross-fostering breeding experiment on zebra finches, Taeniopygia guttata, we demonstrate for the first time that parental personality traits and the combination of personalities within breeding pairs can have positive effects on correlates of (foster) offspring fitness (body mass and condition). Furthermore these non-genetic parental effects are pervasive and carry-over into the next generation. Our results suggest that similarity in behavioural traits of biparental species can have important, long-lasting effects on reproductive success, most likely due to reduced sexual conflict over the provision of parental investment.
Abstract.
Royle NJ, Hall ME, Blount JD, Forbes S (2011). Patterns of egg yolk antioxidant co-variation in an avian brood parasite-host system.
Behavioral Ecology and Sociobiology,
65(2), 313-323.
Abstract:
Patterns of egg yolk antioxidant co-variation in an avian brood parasite-host system
Despite their importance to offspring fitness outcomes, there has been little previous work on egg-mediated maternal effects in avian brood parasites which lay their eggs in the nests of other species. Here, we examine patterns of egg yolk antioxidant deposition in an avian host (red-winged blackbird, Agelaius phoeniceus) and their brood parasite (brown-headed cowbird, Molothrus ater). Cowbird nestlings compete directly for food with host blackbird chicks and succeed, despite hatching from a smaller egg, by begging more intensely and growing as or more rapidly than their hosts. Dietary-derived antioxidants, such as carotenoids and vitamins E and A, deposited in egg yolk, may enhance growth rate and reduce oxidative stress, and therefore provide a potential mechanism by which female cowbirds could enhance the competitiveness of their young in host nests. However, provision of antioxidants to eggs is costly so we predicted that female cowbirds should adjust the amount of antioxidants in response to variation in host quality. We found that whilst red-winged blackbird clutches parasitised by cowbirds did not differ in the pattern of antioxidant deposition compared to non-parasitised clutches, levels of vitamin E deposited in cowbird eggs were closely matched to that of the individual host clutch in which cowbirds laid their egg. This supports the prediction that female cowbirds adjust the antioxidant concentration of their eggs to increase the likely competitiveness of their offspring in the host nest into which they are laid and may help explain the success of cowbirds in competing with larger host young. © 2010 Springer-Verlag.
Abstract.
2010
Royle NJ, Schuett W, Dall SRX (2010). Behavioural consistency and the resolution of sexual conflict over parental care. BEHAVIORAL ECOLOGY, 21, 1125-1130.
Walling CA, Royle NJ, Lindström J, Metcalfe NB (2010). Do female association preferences predict the likelihood of reproduction?.
Behavioral Ecology and Sociobiology,
64(4), 541-548.
Abstract:
Do female association preferences predict the likelihood of reproduction?
Sexual selection acting on male traits through female mate choice is commonly inferred from female association preferences in dichotomous mate choice experiments. However, there are surprisingly few empirical demonstrations that such association preferences predict the likelihood of females reproducing with a particular male. This information is essential to confirm association preferences as good predictors of mate choice. We used green swordtails (Xiphophorus helleri) to test whether association preferences predict the likelihood of a female reproducing with a male. Females were tested for a preference for long- or short-sworded males in a standard dichotomous choice experiment and then allowed free access to either their preferred or non-preferred male. If females subsequently failed to produce fry, they were provided a second unfamiliar male with similar sword length to the first male. Females were more likely to reproduce with preferred than non-preferred males, but for those that reproduced, neither the status (preferred/non-preferred) nor the sword length (long/short) of the male had an effect on brood size or relative investment in growth by the female. There was no overall preference based on sword length in this study, but male sword length did affect likelihood of reproduction, with females more likely to reproduce with long- than short-sworded males (independent of preference for such males in earlier choice tests). These results suggest that female association preferences are good indicators of female mate choice but that ornament characteristics of the male are also important. © 2009 Springer-Verlag.
Abstract.
Hall ME, Blount JD, Forbes S, Royle NJ (2010). Does oxidative stress mediate the trade-off between growth and self-maintenance in structured families?.
Functional Ecology,
24(2), 365-373.
Abstract:
Does oxidative stress mediate the trade-off between growth and self-maintenance in structured families?
Life-history theory predicts a trade-off between growth and self-maintenance. However, little is known about the underlying mechanisms. Oxidative stress, the imbalance between the production of reactive oxygen species (ROS) during normal metabolic processes and the level of antioxidant defences, is a potential mechanism. In many altricial birds asynchronous hatching creates different castes of progeny as a hedge against developmental and environmental uncertainty (a 'structured' family). Older, 'core' offspring and later hatched 'marginal' offspring consequently experience contrasting levels of resource availability during development. To be adaptive the phenotypic handicap incurred by marginal offspring must be reversible when conditions allow. Dietary-derived antioxidants are an important component of antioxidant defences, which modulate oxidative damage arising from normal metabolic processes such as growth. Dietary antioxidants could therefore be important determinants of trade-offs during growth, with the balance of these trade-offs differing between core and marginal offspring. To investigate this, we manipulated brood size and structure as well as antioxidant availability (by vitamin and mineral supplementation), then measured growth and oxidative damage in nestling red-winged blackbirds Agelaius phoeniceus. We found that individuals supplemented with dietary antioxidants allocated these extra resources to increasing growth rate, rather than reducing oxidative damage. Irrespective of hatch rank, nestlings that received supplementary antioxidants grew faster than controls, despite no difference in their begging behaviour or parental provisioning rates. There was no overall difference in the level of lipid peroxidation (malondialdehyde; MDA) in the blood plasma of supplemented and control chicks, but among marginal offspring those that received an antioxidant supplement had lower plasma MDA. Antioxidant supplementation did not affect nestling survival to fledging age. These novel results support the idea that oxidative stress may play a central role in the trade-off between growth and self-maintenance. Moreover, they further highlight the importance of physiological costs in the evolution of life-histories and propose a role for oxidative stress in the adaptive basis of the structured family. © 2009 the Authors. Journal compilation © 2009 British Ecological Society.
Abstract.
Royle NJ, Pike TW (2010). Social feedback and attractiveness in zebra finches.
Behavioral Ecology and Sociobiology,
64(12), 2015-2020.
Abstract:
Social feedback and attractiveness in zebra finches
The attractiveness of an individual (i. e. its ability to arouse interest in a potential mate) has important implications for its reproductive success. However, attractiveness is not a fixed trait. Previous work has shown that male birds can adjust the intensity of their courtship display in response to variation in female behaviour, but little is known about how males adjust their behaviour during mate choice in response to social feedback about their own attractiveness independent of their intrinsic quality. Such information may help to maximize the potential mating success of males. Here, we provide experimental evidence that the amount of attention given by male zebra finches to females is dependent upon the manipulated attractiveness of males. This demonstrates that, in this socially monogamous species of bird, attractiveness of males could be considered to be a social construct, at least partially determined via social feedback from females. © 2010 Springer-Verlag.
Abstract.
2009
Archer CR, Royle N, South S, Selman C, Hunt J (2009). Nutritional geometry provides food for thought.
J Gerontol a Biol Sci Med Sci,
64(9), 956-959.
Abstract:
Nutritional geometry provides food for thought.
Dietary Restriction extends lifespan in a diverse range of animals, but this often comes at a cost to reproduction. While a number of molecular pathways integral to these relationships have been characterised, we still do not fully understand whether restriction of specific nutrients or calories is responsible. Two recent studies on insects have offered novel insights into this longstanding issue via the application of Nutritional Geometry. This technique promises to significantly advance our understanding of how nutrition influences reproduction and longevity.
Abstract.
Author URL.
2008
Samanta, M. Lindström, J. Royle, N.J. (2008). Behavioural phenotype affects social interactions in an animal social network. Proceedings of the Royal Society B, 275, 2515-2520.
Lindström, J. Metcalfe, N.B. (2008). Context-dependent mate choice in relation to social composition in green swordtails <em>Xiphophorus helleri</em>. Behavioral Ecology, 19, 998-1005.
Royle, N.J. Lindström, J. Metcalfe, N.B. (2008). Experience-induced preference for short-sworded males in the green swordtail <em>Xiphophorus helleri</em>. Animal Behaviour, 76, 271-276.
Harris, W.E. Royle, N.J. (2008). The capture of heritable variation for genetic quality through social competition. Genetica, 134, 89-97.
2007
Royle, N.J. Metcalfe, N.B. Lindström, J. (2007). Early nutritional conditions, growth trajectories and mate choice: does compensatory growth lead to a reduction in adult attractiveness?. Behavioral Ecology and Sociobiology, 61, 1007-1014.
Royle, N.J. Metcalfe, N.B. Lindström, J. (2007). Green swordtails alter their age at maturation in response to the population level of male ornamentation. Biology Letters, 3, 144-146.
Royle, N.J. (2007). Sexual conflict and its implications for fitness. In Jamieson BGM (Ed) Reproductive biology and phylogeny of Aves (birds).
2006
Hartley, I.R. Parker, G.A. (2006). Consequences of biparental care for begging and growth in zebra finches <em>Taeniopygia guttata</em>. Animal Behaviour, 72, 123-130
Lindström, J. Metcalfe, N.B. (2006). Effect of growth compensation on subsequent physical fitness in green swordtails <em>Xiphophrus helleri</em>. Biology Letters, 2(1), 39-42.
NJRoyle, Lindstrom J, Metcalfe NB (2006). Sexual selection, growth compensation and fast-start swimming performance in green swordtails Xiphophorus helleri. Functional Ecology, 20(4), 662-669.
2005
NJRoyle, Lindstrom J, Metcalfe NB (2005). A poor start in life negatively affects dominance status in adulthood independent of body size in green swordtails Xiphophorus helleri. Proceedings of the Royal Society B Biological Sciences, 272(1575), 1917-1922.
Metcalfe, N.B. Royle, N.J. (2005). How are animals with ornaments predicted to compensate for a bad start in life? a dynamic optimization approach. Functional Ecology, 19, 421-428.
2004
Hartley, I.R. Parker, G.A. (2004). Parental investment and family dynamics: Interactions between theory and empirical tests. Population Ecology, 46, 231-241
2003
Surai, P.F. Hartley, I.R. (2003). The effect of variation in dietary intake on maternal deposition of antioxidants in zebra finch eggs. Functional Ecology, 17(4), 472-481.
2002
Parker, G.A. Hartley, I.R. (2002). Begging for control: when are offspring solicitation behaviours honest?. Trends in Ecology & Evolution, 17(9), 434-440.
Royle, N.J. Hartley, I.R. (2002). Begging scrambles with unequal chicks: interactions between need and competitive ability. Ecology Letters, 5, 206-215.
Royle, N.J. Hartley, I.R. (2002). Intra-familial conflict and parental investment: a synthesis. Philosophical Transactions of the Royal Society B, 357, 295-307.
NJRoyle, Hartley IR, Parker GA (2002). Sexual conflict reduces offspring fitness in zebra finches. Nature, 416(6882), 733-736.
2001
NJRoyle, Hartley IR, Surai PF (2001). Maternally derived androgens and antioxidants in bird eggs: complementary but opposing effects? . Behavioral Ecology, 12(4), 381-385.
2000
Surai PF, Royle NJ, Sparks NH (2000). Fatty acid, carotenoid and vitamin a composition of tissues of free living gulls.
Comp Biochem Physiol a Mol Integr Physiol,
126(3), 387-396.
Abstract:
Fatty acid, carotenoid and vitamin a composition of tissues of free living gulls.
The aim of this study was to investigate fatty acid and carotenoid profile as well as vitamin a (retinol and retinol esters) content in gull (Larus fucus) tissues. Palmitic (16:0) and stearic (18:0) fatty acids were major saturates in all the tissues studied. Oleic acid (18:1n-9) was the major monounsaturate in the tissue phospholipids varying from 11.9% (liver) up to 18.2% (lung). Arachidonic acid (20:4n-6) was the major unsaturate in the phospholipid fraction in all the tissues. Liver contained the highest total carotenoid concentration which was 5 and 7 fold higher compared to kidney and pancreas. In the liver beta-carotene was major carotenoid. In contrast, in all other tissues beta-carotene was minor fraction with lutein being major carotenoid. Zeaxanthin, canthaxanthin, beta-cryptoxanthin and echinenone were also identified in the gull tissues. Liver and kidney were characterised by the highest vitamin a concentrations (1067.5 and 867.5 microg/g, respectively). Retinol comprised from 55.3% (pancreas) down to 8% (kidney) of the total vitamin a but was not detected in the abdominal fat. Retinyl palmitate was the major retinyl ester in the liver, kidney and heart (44.2; 38.1 and 46.0% of total retinyl esters). In muscles and abdominal fat retinyl stearate was the major retinyl ester fraction. Therefore high proportions of beta-carotene were found in gull liver and peripheral tissues were enriched by lutein and zeaxanthin compared to the liver, a very high concentration of retinyl esters in the kidney was observed and tissue-specificity in retinyl ester proportions in peripheral tissues was found.
Abstract.
Author URL.
Hartley IR, Royle NJ, Shepherd M (2000). Growth rates of nestling Corn Buntings Miliaria calandra in relation to their sex. Ibis, 142(4), 668-671.
Royle N (2000). Overproduction in the lesser black-backed gull - can marginal chicks overcome the initial handicap of hatching asynchrony?.
Journal of Avian Biology,
31(3), 335-344.
Abstract:
Overproduction in the lesser black-backed gull - can marginal chicks overcome the initial handicap of hatching asynchrony?
In response to unpredictability of both food availability and core offspring failure, parents of many avian species initially produce more offspring than they commonly rear (overproduction). When parental investment is insufficient to raise the whole brood the handicap of hatching last means 'marginal' chicks are less likely to survive if brood reduction occurs. Conversely, if marginal offspring are required as replacements for failed 'core' chicks, or parental investment is sufficient to rear the whole brood, the handicap imposed on marginal chicks must be reversible if overproduction is to be a viable strategy. I investigated the ability of marginal offspring to overcome the handicap imposed by hatching asynchrony using a combination of a field experiment, designed to manipulate both the amount of total competition and the relative competitive ability of chicks within a brood, and data on the growth and survival of unmanipulated, three-chick broods from three consecutive years. The results indicate that, even when resources are abundant, marginal offspring do not begin to overcome the competitive handicap imposed by hatching asynchrony until the period of growth when energetic requirements reach their peak, and subsequent survival to fledging is almost assured. This is apparently a consequence of parents controlling allocation of early parental investment, so that any brood reduction 'decisions' can be left as late as possible. Marginal chicks initially channel resources into maintaining mass, relative to skeletal size, as a buffer against starvation. However this also means competitiveness is reduced, so if conditions are poor marginal chicks are rapidly out-competed, lose condition and die. Conversely, when food availability is good marginal offspring devote more resources to skeletal growth and quickly close the gap on their core siblings, meaning the handicap is reversible. The benefits of overproduction and hatching asynchrony as reproductive strategies to maximise success in Lesser Black-backed Gulls are discussed in relation to the reproductive alternatives.
Abstract.
1999
Royle NJ, Surai PF, McCartney RJ, Speake BK (1999). Parental investment and egg yolk lipid composition in gulls.
Functional Ecology,
13(3), 298-306.
Abstract:
Parental investment and egg yolk lipid composition in gulls
1. Within-clutch variation in parental investment of yolk lipid (including essential fatty acid composition and fat-soluble vitamin content) was investigated in whole clutches of three eggs of Lesser Black-backed Gulls, Larus fuscus. 2. Although there were no significant differences between years in egg size or yolk mass among eggs of the same laying order, eggs collected in 1996 had significantly lower lipid content than those collected in 1997. 3. In both years third-laid c-eggs were smaller, had a smaller mass of yolk and had significantly lower yolk lipid mass compared with earlier laid (a- and b-) eggs. 4. Despite this lower lipid mass of c-eggs, of the different lipid fractions only cholesterol content of c-eggs was significantly lower than that of a- or b-eggs. 5. Earlier laid eggs had greater amounts of arachidonic acid in the phospholipid and cholesterol ester fractions of yolk lipid, and considerably greater quantities of vitamin E and carotenoids. 6. Conversely, levels of linoleic acid and vitamin a were equalized among eggs of different laying sequence as both these essential nutrients have primarily systemic roles. 7. The probable effect of increased antioxidant (vitamin E and carotenoid) content of earlier-laid eggs is to enhance embryonic and neonatal growth and development, reduce susceptibility to pathogens and increase the ability of the embryo to withstand the oxidative stress associated with hatching. 8. The results suggest that there is maternal bias of essential nutrients to offspring with the highest reproductive value in order to maximize reproductive success.
Abstract.
Royle NJ, Hartley IR, Owens IPF, Parker GA (1999). Sibling competition and the evolution of growth rates in birds.
Proceedings of the Royal Society B: Biological Sciences,
266(1422), 923-932.
Abstract:
Sibling competition and the evolution of growth rates in birds
Variation among bird species in growth rates is traditionally attributed to differences in energy availability and developmental mode. However, the extent and form of competition among siblings for limited food resources may also be an important determinant. Kin-selection-based models of intrabrood competition suggest that nestling growth rates should be highest in those species in which siblings are likely to be less genetically related to one another (half-sibs rather than full-sibs). We test this novel prediction using the frequency of multiple paternity as an index of average sib relatedness within broods. As predicted, we find a significant positive association between the rate of multiple paternity within broods and nestling growth rates. Furthermore, this holds true when we control for the effects of variation in other factors that may be associated with variation in growth rate, such as body size, brood size, mating system and the form of parental care. We suggest, therefore, that variation in growth rate among bird species is not simply dependent on proximate ecological and developmental factors but is also strongly influenced by interactions, over an evolutionary time-scale, among kin.
Abstract.
1998
Royle NJ, Hamer KC (1998). Hatching asynchrony and sibling size hierarchies in gulls: Effects on parental investment decisions, brood reduction and reproductive success.
Journal of Avian Biology,
29(3), 266-272.
Abstract:
Hatching asynchrony and sibling size hierarchies in gulls: Effects on parental investment decisions, brood reduction and reproductive success
We manipulated the within-brood mass hierarchy of Lesser Black-backed Gulls Larus fuscus, controlling for chick quality (related to laying order) by swapping last hatched (c-) chicks in experimental broods with a- or b- chicks from residual broods to create either synchronous broods (all 3 chicks in the brood approximately the same mass) or asynchronous broods (same within-brood difference in mass between largest and smallest chicks as that of unmanipulated broods), whilst also controlling for variation in characteristics of parental quality (clutch size, egg size and timing of laying). Subsequent chick growth and survival for each brood were monitored in comparison with naturally asynchronous, unmanipulated broods in order to assess the effect of hatching asynchrony per se on chick growth and survival. There were no differences among treatments in fledging success or growth characteristics of surviving chicks. However, chick mortality occurred significantly later in synchronous broods and this was a consequence of the smaller within-brood hierarchical differences in size and body condition of these chicks. Apparently, parents could not regulate resource allocation in synchronous broods, and invested a greater amount of parental investment in chicks that later died. The results indicate that (1) the degree of hatching asynchrony may be optimized with respect to the prevailing food supply and/or female nutritional condition, and (2) the degree of hatching asynchrony is more important than initial within-clutch differences in egg or chick quality in determining the outcome of sibling rivalry over parental investment.
Abstract.