Understanding the unexplained: The magnitude and correlates of individual differences in residual variance

Mitchell, David J.; Beckmann, Christa; Biro, Peter A.

doi:10.1002/ece3.7603

Cited by 33 publications

(41 citation statements)

References 123 publications

(220 reference statements)

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“…Higher values of CV P for a behavior indicate the population is composed of individuals that vary in their rIIV (i.e., a mixture of predictable and unpredictable individuals), whereas a lower value for CV P indicates that individuals express similar levels of behavioral variation around their respective behavioral types. We describe our results for CV P as higher or lower with reference to a meta-analysis which summarized 64 estimates of CV P from 39 studies indicated that behavioral traits had mean CV P of 0.27 [0.22, 0.33] ( 35 ).…”

Section: Methodsmentioning

confidence: 99%

Repeatability and Predictability of Calf Feeding Behaviors—Quantifying Between- and Within-Individual Variation for Precision Livestock Farming

et al. 2022

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Individual calves show substantial between- and within-individual variation in their feeding behavior, the existence and extent of which are not fully researched. In this study, 57,196 feeding records, collected by a computerized milk feeder from 48 pre-weaned calves over 5 weeks, were collated and analyzed for individual differences in three different feeding behaviors using a multi-level modeling approach. For each feeding behavior, we quantified behavioral variation by calculating repeatability and the coefficient of variation in predictability. Our results indicate that calves differed from each other in their average behavioral expression (behavioral type) and in their residual, within individual variation around their behavioral type (predictability). Feeding rate and total meals had the highest repeatability (>0.4) indicating that substantial, temporally stable between-individual differences exist for these behaviors. Additionally, for some behaviors (e.g., feeding rate) calves varied from more to less predictable whereas for other behaviors (e.g., meal size) calves were more homogenous in their within-individual variation around their behavioral type. Finally, we show that for individual calves, behavioral types for feeding rate and total meals were positively correlated which may suggest the existence of an underlying factor responsible for driving the (co)expression of these two behaviors. Our results highlight how the application of methods from the behavioral ecology literature can assist in improving our understanding of individual differences in calf feeding behavior. Furthermore, by uncovering consistencies between individual behavioral differences in calves, our results indicate that animal personality may play a role in driving variability in calf feeding behavior.

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Section: Methodsmentioning

confidence: 99%

Repeatability and Predictability of Calf Feeding Behaviors—Quantifying Between- and Within-Individual Variation for Precision Livestock Farming

et al. 2022

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“…The recent increase in studies looking at intra-individual variability in behaviour has allowed researchers to improve their understanding of the biological significance of these differences (Mitchell et al, 2021;Westneat et al, 2015). Any trait that changes along a gradient will show variability.…”

Section: Discussionmentioning

confidence: 99%

Albatrosses respond adaptively to climate variability by changing variance in a foraging trait

Patrick

Martin

Ummenhofer

et al. 2021

Global Change Biology

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The ability of individuals and populations to adapt to a changing climate is a key determinant of population dynamics. While changes in mean behaviour are well studied, changes in trait variance have been largely ignored, despite being assumed to be crucial for adapting to a changing environment. As the ability to acquire resources is essential to both reproduction and survival, changes in behaviours that maximize resource acquisition should be under selection. Here, using foraging trip duration data collected over 7 years on black‐browed albatrosses (Thalassarche melanophris) on the Kerguelen Islands in the southern Indian Ocean, we examined the importance of changes in the mean and variance in foraging behaviour, and the associated effects on fitness, in response to the El Niño Southern Oscillation (ENSO). Using double hierarchical models, we found no evidence that individuals change their mean foraging trip duration in response to a changing environment, but found strong evidence of changes in variance. Younger birds showed greater variability in foraging trip duration in poor conditions as did birds with higher fitness. However, during brooding, birds showed greater variability in foraging behaviour under good conditions, suggesting that optimal conditions allow the alteration between chick provisioning and self‐maintenance trips. We found weak correlations between sea surface temperature and the ENSO, but stronger links with sea‐level pressure. We suggest that variability in behavioural traits affecting resource acquisition is under selection and offers a mechanism by which individuals can adapt to a changing climate. Studies which look only at effects on mean behaviour may underestimate the effects of climate change and fail to consider variance in traits as a key evolutionary force.

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“…We further analyzed behavioral data using a double-hierarchical LMMs (DHGLM) in a Bayesian framework with the R package “brms” (Bürkner 2017 , 2018 ). DHGLM allows fitting simultaneously the mean and dispersion levels by considering both fixed and random effects ( Cleasby et al 2015 ; Mitchell et al 2016 , 2021 ; Hertel et al 2020, 2021 ). DHGLM is recommended to estimate variation in intra-individual variability ( rIIV ) and to compare behavioral predictability between groups or treatments because they can model the structure of residual variance ( Cleasby et al 2015 ; Mitchell et al 2021 ).…”

Section: Methodsmentioning

confidence: 99%

“…DHGLM allows fitting simultaneously the mean and dispersion levels by considering both fixed and random effects ( Cleasby et al 2015 ; Mitchell et al 2016 , 2021 ; Hertel et al 2020, 2021 ). DHGLM is recommended to estimate variation in intra-individual variability ( rIIV ) and to compare behavioral predictability between groups or treatments because they can model the structure of residual variance ( Cleasby et al 2015 ; Mitchell et al 2021 ). We consider observations (Tests 1–10) and source colonies as fixed factors in the mean model.…”

Section: Methodsmentioning

confidence: 99%

“…The random factors in the mean model were ant ID and nest ID (i.e., the ID of nests in which workers emerged). In the residual model, we specified a random intercept (ant ID) to estimate individual differences in predictability ( Mitchell et al 2021 ). Values of model parameters were considered significant when 95% credible intervals did not overlap zero.…”

Section: Methodsmentioning

confidence: 99%

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Early social context does not influence behavioral variation at adulthood in ants

Sanmartín‐Villar

Jeanson

2021

Current Zoology

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Early experience can prepare offspring to adapt their behaviors to the environment they are likely to encounter later in life. In several species of ants, colonies show ontogenic changes in the brood-to-worker ratio that are known to have an impact on worker morphology. However, little information is available on the influence of fluctuations in the early social context on the expression of behavior in adulthood. Using the ant Lasius niger, we tested whether the brood-to-worker ratio during larval stages influenced the level of behavioral variability at adult stages. We raised batches of 20 or 180 larvae in the presence of 60 workers until adulthood. We then quantified the activity level and wall-following tendency of callow workers on ten successive trials to test the prediction that larvae reared under a high brood-to-worker ratio should show greater behavioral variations. We found that manipulation of the brood-to-worker ratio influenced the duration of development and the size of individuals at emergence. We detected no influence of early social context on the level of between- or within individual variation measured for individual activity level or on wall-following behavior. Our study suggests that behavioral traits may be more canalized than morphological traits.

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Understanding the unexplained: The magnitude and correlates of individual differences in residual variance

Cited by 33 publications

References 123 publications

Repeatability and Predictability of Calf Feeding Behaviors—Quantifying Between- and Within-Individual Variation for Precision Livestock Farming

Repeatability and Predictability of Calf Feeding Behaviors—Quantifying Between- and Within-Individual Variation for Precision Livestock Farming

Albatrosses respond adaptively to climate variability by changing variance in a foraging trait

Early social context does not influence behavioral variation at adulthood in ants

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