Data from: Mitochondrial function predicts dominance status in brown trout
Data files
Dec 10, 2025 version files 21.63 KB
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Data_for_Dryad_-_McLennan_et_al._2025._Functional_Ecology.xlsx
16.98 KB
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README.md
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Abstract
In social hierarchies, winning contests confers better access to food, shelter, and reproductive opportunities. Clear dominance relationships are often apparent even when opponents are matched for experience, age, size, and other obvious characteristics. One explanation for this could be among-individual differences in mitochondrial function, since this could be associated with the cellular allocation of energy to dominance-associated traits.
Here, we tested whether the dominance status of juvenile brown trout (Salmo trutta) was related to their mitochondrial function. We determined each fish’s dominance status by staging a series of contests for a feeding territory in an artificial stream tank; observations of colouration, food acquisition, and aggressive behaviour allowed the assignment of dominance. Mitochondrial function (the capacity for ATP production, and the efficiency with which ATP is produced) was then measured in the muscles used for swimming, analysed at the level of both homogenised tissue and isolated mitochondria.
We found that a fish’s net phosphorylation efficiency (i.e., the efficiency with which ATP is produced) was a significant predictor of its dominance-associated colouration and the level of aggression it exhibited towards an opponent. However, a fish’s overall dominance status was instead predicted by its capacity for oxidative phosphorylation (i.e. ATP production capacity). Moreover, oxidative phosphorylation was also a significant predictor of whether a fish would be categorised as being subordinate or dominant in a binary classification.
While it is now well established that organism-level metabolism is a fundamental trait linking an individual’s ecology, physiology and life history, it is only relatively recently that the causes of among-individual variation in this trait have been investigated, with a shift in focus towards the ways in which energy is produced at a cellular level. By showing that mitochondrial function is related to competitive ability, this study exemplifies how cellular energy production can influence contest outcomes and thus the architecture of social hierarchies.
https://doi.org/10.5061/dryad.n8pk0p38m
This dataset was collected and analysed by the authors of the paper “Mitochondrial function predicts dominance status in brown trout”, which is published in the journal Functional Ecology. Data_for_Dryad_-_McLennan_et_al._2025._Functional_Ecology.xlsx
Description of the data and file structure:
Please see below for an overview of each variable:
- Fish ID ~ This is the unique ID that we assigned to each of the trout.
- Tag ~ Each of the four fish within a cohort had a unique VIE tag (i.e., one yellow, one red, one green and one white).
- Cohort ~ The experimental cohort that each fish belonged to.
- Colouration score ~ Fish were assigned a score at each observation period, depending on whether they were relatively brighter (indicating dominance) or darker (indicating subordination). Range = -24 to 24.
- Food capture score ~ The number of food items that were captured by an individual in relation to the number of food items that were captured overall. Expressed as a percentage. Range = 0 to 100.
- Aggression score ~ Fish were assigned a score at each observation period, depending on the number of agnostic interactions between the two individuals and whether they were the initiator or recipient. Range = -152 to 312.
- Dominance score ~ The first three scores were summarised into one latent variable using principal components analysis, thus assigning each individual an overall dominance score. Range = -2.38 to 2.27.
- Dominance rank ~ Each individual was categorised as either subordinate (individuals with a PC1 score below 0) or dominant (individuals above 0).
- Sex ~ Individuals were assigned as male or female using a conventional PCR sexing assay.
- Fork length ~ The length of each individual measured to the nearest 1mm, from the most anterior point of the head to the fork of the tail. Measured the day prior to entering the trials. Range = 46.7 to 53.7.
- Mito level OXPHOS ~ The oxygen consumption rate during oxidative phosphorylation per µg of protein from isolated mitochondria. This oxygen consumption rate was measured in the presence of all substrates (pyruvate, malate, glutamate and succinate) and saturating levels of ADP. Measured as pmol O2.s-1.ug-1. Range = 0.48 to 2.22.
- Mito level OxCE ~ A measure of mitochondrial oxygen consumption efficiency for isolated mitochondria. OXPHOS Coupling Efficiency (OxCE) is a standardisation between 0 and 1 of the respiratory control ratio (RCR; ratio of OXPHOS to Leak respiration after addition of oligomycin). OxCE = 1 – (1/RCR). Unitless. Range = 0.75 to 0.92.
- Tissue level OXPHOS ~ The maximum oxygen consumption rate per mg of wet weight shredded tissue preparation. This oxygen consumption rate was measured in the presence of all substrates (pyruvate, malate, glutamate and succinate) and saturating levels of ADP. Measured as pmol.s-1.mg-1. Range = 3.81 to 13.50. It was not possible to measure tissue level mitochondrial traits in one of the cohorts due to a technical failure, therefore n = 44 for this variable.
- Tissue level OxCE ~ A measure of mitochondrial oxygen consumption efficiency for the shredded tissue preparation. OXPHOS Coupling Efficiency (OxCE) is a standardisation between 0 and 1 of the respiratory control ratio (RCR; ratio of OXPHOS over the Leak respiration after addition of oligomycin). OxCE = 1 – (1/RCR). Unitless. Range = 0.78 to 0.93. It was not possible to measure tissue level mitochondrial traits in one of the cohorts due to a technical failure, therefore n = 44 for this variable.
- Oxygraph chamber ~ The Oxygraph-2k chamber (out of four) that was used to measure an individual's mitochondrial physiology.
- CS ~ The rate of Citrate Synthase activity. Used as a quantitative proxy of mitochondrial volume. Measured as umol.g-1.min-1. Range = 5.85 to 12.54. It was not possible to measure tissue level mitochondrial traits in one of the cohorts due to a technical failure, therefore n = 44 for this variable.
- Tissue level OXPHOS/CS ~ The oxygen consumption rate during oxidative phosphorylation per mg of wet weight shredded tissue preparation, divided by CS activity in the same tissue. This oxygen consumption rate was measured in the presence of all substrates (pyruvate, malate, glutamate and succinate) and saturating levels of ADP. Measured as nmol O2/µmol. Range = 0.36 to 2.00. It was not possible to measure tissue level mitochondrial traits in one of the cohorts due to a technical failure, therefore n = 44 for this variable.