Data from: Asymmetrical evolution of cross inhibition in zooplankton: Insights from contrasting phosphorus limitation and salinization exposure sequences
Data files
Nov 17, 2025 version files 49.21 KB
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Algal_stoichiometry.csv
236 B
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Food_algae_size_density.csv
1.48 KB
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Population_growth_rates.csv
43.74 KB
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README.md
3.76 KB
Abstract
Understanding the evolutionary responses of organisms to multiple stressors is crucial for predicting the ecological consequences of intensified anthropogenic activities. While previous studies have documented the effects of selection history on organisms' abilities to cope with new stressors, the impact of the sequence in which stressors occur on evolutionary outcomes remains less understood. In this study, we examined the evolutionary responses of a metazoan rotifer species to two prevalent freshwater stressors: nutrient limitation and increased salinization. We subjected rotifer populations with distinct selection histories (salt-adapted, low phosphorus-adapted, and ancestral clones) to a reciprocal common garden experiment and monitored their population growth rates. Our results revealed an asymmetric evolutionary response to phosphorus (P) limitation and increased salinity. Specifically, adaptation to low P conditions reduced rotifer tolerance to increased salinity, whereas adaptation to saline conditions enhanced tolerance to P limitation, and such evolved cross-tolerance was more pronounced under moderately saline conditions. Our findings, therefore, underscore the importance of considering historical stressor regimes to improve our understanding and predictions of organismal responses to multiple stressors, and also have significant implications for ecosystem management.
https://doi.org/10.5061/dryad.pk0p2ngxs
Short description of experiment:
To test the impact of adaptation to P limitation or increased salinization on rotifer population growth rate when confronting the alternative stressor, we performed a factorial-designed common garden experiment. Specifically, we assigned rotifer populations with different selection histories (SelHist), i.e., LP adapted, salt adapted and ancestral populations, to the combination of 2 food quality treatments (FoodQual: High P and Low P food) and 2 salinity treatments (SAL: High Sline and Low Saline). For each treatments, we applied 3 clone replictes (Clone) and 3 chemostat replicates (Chem_repl), resulting a total of 108 experimental units. During the experiment, the size of each population were monitored to calculate their population growth rates at daily basis. Meanwhile, we refreshed the food medium and restarted each population by randomly selected and transferred 10 individuals to fresh medium. The experimetn lasted for 9 days and we analyzed the data for last three days where population growth rates for all populations had stabilized.
Features for the algal food, such as cell size and density in the chemostats, were measured by the coulter counter every day. Algal stoichiometric features (i.e., carbon, nitrogen and phosphorus) were also measured at the start of the experiment.
This studies consists of three datafiles:
(1) The dataset ‘Population growth rates.csv’ contains rotifer population counts during the common garden experiment
(2) the dataset ‘Food algae_size_density.csv’ contains cell sizes and cell densities of chemostat cultures used as food source for the rotifers during the common garden experiment
(3) the dataset ‘Algal_stoichiometry.csv’ contains data on the elemental content (carbon, nitrogen and phosphorus) of the algae in the chemostat cultures
Explanation of variables:
Explanatory variables used in multiple data files
- Day: day in the experiment
- Chem_repl: chemostat replicate (3 replicates)
- FoodQual: food quality treatment in common garden experiment: LP: P-limited chemostats; HP: P sufficient chemostats)
Population_growth_rates.csv
Variable names:
- SelHist: factor to which population had adapted during prior selection experiment (LP: LP-food, Salt: saline; Ancest: naieve ancestral)
- Clone: genotype
- SAL: salinity treatment in common garden treatment (in LP treatments: 1.5 g/L NaCl; in HP treatments: 3 g/L NaCl)
- initial: total number of female rotifers at start of time interval
- final: total number of female rotifers at end of time interval
- r: calculated exponential population growth rate (day-1)
Food_algae_size_density.csv
Cell diameters and densities of food algae as characterized with a Coultercounter
Variable names:
- diameter: average cell diameter (µm)
- density: number of cells per mL
Algal_stoichiometry.csv
Variable names:
- Nconc: nitrogen concentration (µmol/L)
- Cconc: carbon concentration (µmol/L)
- Pconc: phosphorus concentration (µmol/L)
- CtoP: molar C:P ratio
- CtoN: molar C:N ratio
- NtoP: molar N:P ratio
Code/Software
Data_Analysis_Annotated.R: This script analyzes how zooplankton evolve cross-tolerance to phosphorus limitation and salinization by modeling growth-rate responses across different environmental and selection histories. It fits mixed-effects models, compares treatment effects, and calculates tolerance differences using paired contrasts and Holm-corrected statistics.