DOI: 10.5061/dryad.m63xsj4cw
title: Data from: Variable stressor exposure shapes fitness within and across generations

description: Environmental variation has long been considered a key driver of
 evolutionary change, predicted to shape different strategies, such as
 genetic specialization, plasticity, or bet-hedging to maintain fitness.
 However, little evidence is available with regards to how the periodicity
 of stressors may impact fitness across generations. To address this gap, I
 conducted a reciprocal split-brood experiment using the freshwater
 crustacean, Daphnia magna, and an ecologically relevant environmental
 stressor, ultraviolet radiation (UVR). I exposed one group to constant and
 another group to fluctuating UVR conditions. Despite receiving the same
 dose of UVR, the first experimental generation displayed significant
 treatment-by-genotype interactions with respect to survival and
 reproductive output, as well as a delayed reproductive maturity under
 fluctuating UVR conditions. In the following experimental generation
 individuals exposed to fluctuating UVR exhibited higher fitness than those
 in a constant UVR regime. The ancestral conditions, i.e, maternal
 environment, however affected the survival probability and reproductive
 output, but did not significantly influence the maturation date. Overall,
 I demonstrate that the delivery of a stressor, not just its intensity, can
 have profound fitness consequences across generations, with important
 implications for seasonal succession of genotype-phenotype patterns in
 natural environments.
description: # Data from: Variable stressor exposure shapes fitness within and across
 generations
 [https://doi.org/10.5061/dryad.m63xsj4cw](https://doi.org/10.5061/dryad.m63xsj4cw) ## Description of the data and file structure To address how the variations of an environmental stressor may affect the life history of *Daphnia*, I quantified longevity, reproductive maturity, as defined by the first day at which eggs were visible in the brood pouch 52, and total reproductive output over each individual´s lifetime. Every individual was checked each day at the same time (±0.5 h). In order to take into account also the offspring’s ‘fitness’, I repeated this design for a second generation using a split brood design. Specifically, I took the first, third, fifth, and seventh broods forward to the next generation as to maximize the number of individuals in generation G4. To assess UV in natural environments, data was collected via lowering a UV sensitive probe through the water column during the middle of the day on a clear sky day. Each of the files ’21_12_30_Field_UVA.csv’, ’21_12_30_Lab_C_UVA.csv’ & ’21_12_30_Lab_F_UVA.csv’ were generated through the deployment of UV data loggers (sglux GmbH, Berlin) calibrated to detect UV-A (315 - 400 nm). They were placed outside the Ecology building, Lund, Sweden, in the lab under the predictable regime lights and in the lab under the unpredictable regime lights respectively.  ### Files and variables #### File: 21\_07\_08\_Field\_UV\_attenuation.csv **Description:**  ##### Variables * Lake: Name of the lake sampled for UV-A depth profile 1\. Ladugårdmarken 2\. Harlösa 3\. Krankesjön 4\. Bysjön 5\. Häljasjön 6\. Havgårdsjön * Depth: The sampled depth i. cm * UV: The value of UV-A recorded at each depth i. µW/cm2 * Percent: The percentage of UV-A as compared to the surface of the water (i.e. 0 cm) i. % #### File: 21\_12\_30\_Field\_UVA.csv **Description:**  ##### Variables * Date: Date each observation was taken * Time: The time each observation was recorded, in the format H:M:S * Temperature_C: The temperature recorded at each observation. Note: this variable was autogenerated by the data logger and not used in any analysis i. ˚C * Raw_UV_Broadband: Despite the title, this sensor was calibrated to detect UV-A not UV-BB, so this column refers to the detected UV-A irradiance at each sampling point. i. W/m2 * UV_Broadband: This column is a conversion of the ‘Raw_UV_Broadband’ column, in order to compare against other datasets with different units i. µW/cm2 #### File: 21\_12\_30\_Lab\_C\_UVA.csv **Description:**  ##### Variables * Date: Date each observation was taken * Time: The time each observation was recorded, in the format H:M:S * Temperature_C: The temperature recorded at each observation. Note: this variable was autogenerated by the data logger and not used in any analysis i. ˚C * Raw_UV_Broadband: Despite the title, this sensor was calibrated to detect UV-A not UV-BB, so this column refers to the detected UV-A irradiance at each sampling point. i. W/m2 * UV_Broadband: This column is a conversion of the ‘Raw_UV_Broadband’ column, in order to compare against other datasets with different units i. µW/cm2 #### File: 21\_12\_30\_Lab\_F\_UVA.csv **Description:**  ##### Variables * Date: Date each observation was taken * Time: The time each observation was recorded, in the format H:M:S * Temperature_C: The temperature recorded at each observation. Note: this variable was autogenerated by the data logger and not used in any analysis i. ˚C * Raw_UV_Broadband: Despite the title, this sensor was calibrated to detect UV-A not UV-BB, so this column refers to the detected UV-A irradiance at each sampling point. i. W/m2 * UV_Broadband: This column is a conversion of the ‘Raw_UV_Broadband’ column, in order to compare against other datasets with different units i. µW/cm2 #### File: 22\_06\_15\_Summary\_data.csv **Description:**  ##### Variables * Genotype: This is reference to the clonal line the individual was isolated from. 1\. D 2\. N 3\. P * Mother_ID: Each individual has a unique number identifier and this is ID number of the mother for that individual * Maternal_Clutch: Multiple broods were taken forward in the experiment, so this identifies from which clutch did each individual arise * Treatment: The treatment group that each individual was placed in, also includes the environment of the mother for the generation G4 1\. C = Predictable UV regime 2\. F = Unpredictable UV regime 3\. CC = The mother was in a predictable UV regime and this individual was also in a predictable UV regime 4\. CF = The mother was in a predictable UV regime but this individual was in an unpredictable UV regime 5\. FC = The mother was in an unpredictable UV regime but this individual was in a predictable UV regime 6\. FF = The mother was in an unpredictable UV regime and this individual was also in an unpredictable UV regime * ID: Personal identification number unique to each individual * Cor.Alive: The number of days alive * Length: The length of each individual measured as from the eye spot to the base of the spine. * mm * Missing value = NA * mean_size_off: Mean size of offspring as measured from all broods that were not taken forward. All offspring were preserved within 24 h of birth and measured in the same manner as above. * mm * Missing value = NA * median_size_off: Median size of offspring as measured from all broods that were not taken forward. All offspring were preserved within 24 h of birth and measured in the same manner as     above. * mm * Missing value = NA * stdv_size_off: Standard deviation of size among offspring as measured from all broods that were not taken forward. All offspring were preserved within 24 h of birth and measured in the     same manner as above. * mm * Missing value = NA * no_off: The number of offspring produce by that individual * Generation: The experimental generation identification 1\. F3 = The generation born 2 generations after the initial experimental isolation 2\. F4 = The generation born 3 generations after the initial experimental isolation * Broods: The number of reproductive events (or clutches/broods) the this individual has produced. * Water.Change: The number of times the water was exchanged for fresh media and food for this individual * Reproductive: The number of days where developing eggs were visible in the brood chamber. * Development: The average time of development for each brood, calculated as the number of days reproductive divided by the number of broods produced. * Missing value = NA * CurrentTreatment: The treatment regime the individual was exposed to - I.e., ignoring the ancestral treatment regime *  C = individual exposed to a predictable UV regime *  F = individual exposed to a unpredictable UV regime * Mature: The day at which the individual became reproductively mature, which is to say eggs were visible in the brood chamber. * Missing value = NA * off_diff: The difference in the number of offspring between daughters and mothers. * Missing value = NA ## Code/software R v. 4.4.2 was used to analyse the associated data. All packages can be found within the attached script. The script provides all analyses used in the manuscript and produces the figures.