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Social genetic and social environment effects on parental and helper care in a cooperatively breeding bird.

Adams MJ, Robinson MR, Mannarelli ME, Hatchwell BJ - Proc. Biol. Sci. (2015)

Bottom Line: Controlling for other effects, individuals were consistent in their provisioning effort at a given nest, but adjusted their effort based on who was in their social group, indicating the presence of social effects.However, these social effects differed between years and social contexts, indicating a current environment effect, rather than indicating a genetic or permanent environment effect.While this study reveals the importance of examining environmental and genetic sources of social effects, the framework we present is entirely general, enabling a greater understanding of potentially important social effects within any ecological population.

View Article: PubMed Central - PubMed

Affiliation: Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK m@differentialist.info.

ABSTRACT
Phenotypes expressed in a social context are not only a function of the individual, but can also be shaped by the phenotypes of social partners. These social effects may play a major role in the evolution of cooperative breeding if social partners differ in the quality of care they provide and if individual carers adjust their effort in relation to that of other carers. When applying social effects models to wild study systems, it is also important to explore sources of individual plasticity that could masquerade as social effects. We studied offspring provisioning rates of parents and helpers in a wild population of long-tailed tits Aegithalos caudatus using a quantitative genetic framework to identify these social effects and partition them into genetic, permanent environment and current environment components. Controlling for other effects, individuals were consistent in their provisioning effort at a given nest, but adjusted their effort based on who was in their social group, indicating the presence of social effects. However, these social effects differed between years and social contexts, indicating a current environment effect, rather than indicating a genetic or permanent environment effect. While this study reveals the importance of examining environmental and genetic sources of social effects, the framework we present is entirely general, enabling a greater understanding of potentially important social effects within any ecological population.

No MeSH data available.


Related in: MedlinePlus

Diagram of social effects models, showing how behaviour of a focal individual (bird 1) over years 1 and 2 is modelled with direct and social effects. For clarity, fixed effects and nest effects are not visualized. (a) Baseline models (1A and 2A) of direct effects from focal bird 1 on its own behaviour. (b) Social identify effect models (1B and 2B) of the effect of bird 1's social partners (birds 2 and 3) on its behaviour. (c) Social environment models (1C and 2C) split social effects into permanent environment effects (consistent across years) and current environment effects (consistent within years). (d) Social genetic models (1D and 2D) partition permanent effects into a permanent environment component and a permanent genetic component. Curr., current; perm., permanent; genet., genetic; env., environment.
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RSPB20150689F1: Diagram of social effects models, showing how behaviour of a focal individual (bird 1) over years 1 and 2 is modelled with direct and social effects. For clarity, fixed effects and nest effects are not visualized. (a) Baseline models (1A and 2A) of direct effects from focal bird 1 on its own behaviour. (b) Social identify effect models (1B and 2B) of the effect of bird 1's social partners (birds 2 and 3) on its behaviour. (c) Social environment models (1C and 2C) split social effects into permanent environment effects (consistent across years) and current environment effects (consistent within years). (d) Social genetic models (1D and 2D) partition permanent effects into a permanent environment component and a permanent genetic component. Curr., current; perm., permanent; genet., genetic; env., environment.

Mentions: In long-tailed tits, all adults attempt to breed every year, often with different partners over the course of their lives owing to mortality and divorce [23]. Nests often fail because of high nest predation [24], and some failed breeders become helpers at the nest of another pair [25] who are usually, but not always, relatives [26,27]. The presence of helpers leads to an increase in total provisioning rate and nestling mass [28], as well as a decrease in the provisioning rate by individual parents [29,30]. From this modulation of parental effort by the presence of helpers, we hypothesized that there are social effects between parents and helpers, and that these effects are neither completely additive nor completely compensatory. To investigate social effects on caring behaviour in this species, we extended the indirect effects modelling framework [31] in two ways. First, because we had observed individuals multiple times within and across years, we were able to partition individual variance into genetic effects and two environment effects: permanent environment effects that persist over an individual's lifetime and current environment effects that differ between years (figure 1). We were thus able to estimate how much social effects varied between years as a test of whether social effects could be condition-dependent. Second, in their social groups, birds take on one of two social roles: that of parent or helper. We were able, therefore, to further partition the social environment effects into those from parents and those from helpers. Finally, a social effect is defined by behavioural plasticity, because the effect captures the responsiveness of a focal individual to the presence or behaviour of a particular social partner. However, a focal individual may also respond to other factors that change over time, such as changes in group size and brood demand. Therefore, we also investigated the relative magnitude of within-individual variation attributable to social effects and other factors.FigureĀ 1.


Social genetic and social environment effects on parental and helper care in a cooperatively breeding bird.

Adams MJ, Robinson MR, Mannarelli ME, Hatchwell BJ - Proc. Biol. Sci. (2015)

Diagram of social effects models, showing how behaviour of a focal individual (bird 1) over years 1 and 2 is modelled with direct and social effects. For clarity, fixed effects and nest effects are not visualized. (a) Baseline models (1A and 2A) of direct effects from focal bird 1 on its own behaviour. (b) Social identify effect models (1B and 2B) of the effect of bird 1's social partners (birds 2 and 3) on its behaviour. (c) Social environment models (1C and 2C) split social effects into permanent environment effects (consistent across years) and current environment effects (consistent within years). (d) Social genetic models (1D and 2D) partition permanent effects into a permanent environment component and a permanent genetic component. Curr., current; perm., permanent; genet., genetic; env., environment.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4590478&req=5

RSPB20150689F1: Diagram of social effects models, showing how behaviour of a focal individual (bird 1) over years 1 and 2 is modelled with direct and social effects. For clarity, fixed effects and nest effects are not visualized. (a) Baseline models (1A and 2A) of direct effects from focal bird 1 on its own behaviour. (b) Social identify effect models (1B and 2B) of the effect of bird 1's social partners (birds 2 and 3) on its behaviour. (c) Social environment models (1C and 2C) split social effects into permanent environment effects (consistent across years) and current environment effects (consistent within years). (d) Social genetic models (1D and 2D) partition permanent effects into a permanent environment component and a permanent genetic component. Curr., current; perm., permanent; genet., genetic; env., environment.
Mentions: In long-tailed tits, all adults attempt to breed every year, often with different partners over the course of their lives owing to mortality and divorce [23]. Nests often fail because of high nest predation [24], and some failed breeders become helpers at the nest of another pair [25] who are usually, but not always, relatives [26,27]. The presence of helpers leads to an increase in total provisioning rate and nestling mass [28], as well as a decrease in the provisioning rate by individual parents [29,30]. From this modulation of parental effort by the presence of helpers, we hypothesized that there are social effects between parents and helpers, and that these effects are neither completely additive nor completely compensatory. To investigate social effects on caring behaviour in this species, we extended the indirect effects modelling framework [31] in two ways. First, because we had observed individuals multiple times within and across years, we were able to partition individual variance into genetic effects and two environment effects: permanent environment effects that persist over an individual's lifetime and current environment effects that differ between years (figure 1). We were thus able to estimate how much social effects varied between years as a test of whether social effects could be condition-dependent. Second, in their social groups, birds take on one of two social roles: that of parent or helper. We were able, therefore, to further partition the social environment effects into those from parents and those from helpers. Finally, a social effect is defined by behavioural plasticity, because the effect captures the responsiveness of a focal individual to the presence or behaviour of a particular social partner. However, a focal individual may also respond to other factors that change over time, such as changes in group size and brood demand. Therefore, we also investigated the relative magnitude of within-individual variation attributable to social effects and other factors.FigureĀ 1.

Bottom Line: Controlling for other effects, individuals were consistent in their provisioning effort at a given nest, but adjusted their effort based on who was in their social group, indicating the presence of social effects.However, these social effects differed between years and social contexts, indicating a current environment effect, rather than indicating a genetic or permanent environment effect.While this study reveals the importance of examining environmental and genetic sources of social effects, the framework we present is entirely general, enabling a greater understanding of potentially important social effects within any ecological population.

View Article: PubMed Central - PubMed

Affiliation: Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK m@differentialist.info.

ABSTRACT
Phenotypes expressed in a social context are not only a function of the individual, but can also be shaped by the phenotypes of social partners. These social effects may play a major role in the evolution of cooperative breeding if social partners differ in the quality of care they provide and if individual carers adjust their effort in relation to that of other carers. When applying social effects models to wild study systems, it is also important to explore sources of individual plasticity that could masquerade as social effects. We studied offspring provisioning rates of parents and helpers in a wild population of long-tailed tits Aegithalos caudatus using a quantitative genetic framework to identify these social effects and partition them into genetic, permanent environment and current environment components. Controlling for other effects, individuals were consistent in their provisioning effort at a given nest, but adjusted their effort based on who was in their social group, indicating the presence of social effects. However, these social effects differed between years and social contexts, indicating a current environment effect, rather than indicating a genetic or permanent environment effect. While this study reveals the importance of examining environmental and genetic sources of social effects, the framework we present is entirely general, enabling a greater understanding of potentially important social effects within any ecological population.

No MeSH data available.


Related in: MedlinePlus