Data from: Predators drive selection for adaptive plasticity in prey defense behavior
Data files
Dec 26, 2024 version files 137.13 KB
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actcage.csv
34.61 KB
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actcage2.csv
33.96 KB
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fall2020_mesocosm_predselection_ms.csv
14.28 KB
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fieldbugs_behavioralassays_2021_may.csv
5.35 KB
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README.md
4.32 KB
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wild.act.csv
44.61 KB
Abstract
Plasticity to reduce activity is a common way prey evade predators. However, by reducing activity prey often experience lower individual growth rates because they encounter their own prey less often. To overcome this cost, natural selection should not simply favor individuals generating stronger plasticity to reduce activity rates, but also selection to resume activity once the threat of predation subsides. If such plasticity is adaptive, it should vary under environmental conditions that generate stronger selection for greater plasticity, such as predator density. Using a mesocosm experiment and observational study with a damselfly-prey/fish-predator system we show that fish predation exerts selection for greater plasticity in activity rates of damselflies. Such selection allows damselfly activity levels to initially decrease and then rebound when the threat of predation dissipates, potentially helping to ameliorate a hypothesized growth penalty from activity reductions. We also find that the extent of plasticity in activity to the threat of fish predation increases, albeit slightly (r2 = 0.04-0.063%), as fish densities increase across natural lakes, consistent with the idea that the magnitude of plasticity is shaped by environmental conditions underlying selection. Collectively, these results demonstrate how selection acts to drive adaptive plasticity in a common predator avoidance strategy.
README: Predators drive selection for adaptive plasticity in prey defense behavior
This dataset contains data collected from a mesocosm experiment and a field study investigating damselfly prey behavioral plasticity to fish predators.
Description of the data and file structure
The data are contained in .csv files. The file "fall2020_mesocosm_predselection_ms.csv" contains activity rates of individual damselflies that survived our mesocosm experiment. This file was used for treatment-level analyses. Treatment (caged- or free-fish), tank ID, and cage ID are also included. Each tank contained 3 cages. Headwidths for individuals are included as well and were estimated in ImageJ software from photos of the damselflies taken during the assays. The column "nf1.act.mm" contains activity rates during the initial behavioral assay without fish predator kairomones, "f.act.mm" contains activity rates from the assay with fish kairomones, and "nf2.act.mm" contains activity rates from the assay conducted following the removal of fish kairomones.
The file "actcage.csv" contains the same data for the initial response (without vs. with predator cue) and the file "actcage2.csv" contains data for the reversal response (with vs. without predator cue). These were reformatted in excel for cage-level analyses. Reformatting included transforming the dataset into long format and creating a new column with unique id's for individuals as well as a column for unique cage id's. The "act.mm" column contains activity rates per individual. The "act.avg" column contains average activity rates calculated per cage. The "fish" column reflects our predator cue treatments during behavioral assays. The first assay performed without fish predator kairomones is denoted as -1, assays performed with fish kairomones are denoted as 0, and assays performed after removal of fish kairomones are denoted as 1. The "treatment" column denotes whether that individual was from the caged- or free-fish treatment of our mesocosm study.
The file "fieldbugs_behavioralassays_2021_may.csv" contains activity rate data from behavioral assays performed using field-caught damselflies across 7 different lakes. This data was imported and restructured in R, then exported as a .csv file which we then added our fish density data to. We were unable to record headwidths for damselflies from one of the lakes, which is reflected in the following data file.
The file "wild.act.csv" contains the same data as the above dataset, but fish density for each lake was added as a new column in excel. We then reimported this file into R and calculated mean activity rates of damselflies per lake (column named "mean.act.mm") for each predator cue treatment (column named "fish"). In the "fish" column, -1 denotes no fish kairomones, 0 denotes fish kairomones, and 1 denotes removal of fish kairomones. We also calculated individual (column named "diff") reaction norms for damselfly responses to the presence of fish kairomones by subracting the activity rates in the presence of fish cues from the initial activity rates without fish cues (nf1.act.mm - f.act.mm). Mean reaction norms of this response were estimated per lake (column named "mean.diff") were then estimated. We also calculated individual (recov) and mean (recov.mean) reaction norms for damselfly responses following the removal of fish kairomones in a similar manner. This data was used for analysis of behavioral plasticity of damselflies to fish predators across lakes varying in fish densities. We also calculated individual (column named "diff") reaction norms for damselfly responses to the presence of fish kairomones by subracting the activity rates in the presence of fish cues from the initial activity rates without fish cues (nf1.act.mm - f.act.mm). Mean reaction norms of this response were estimated per lake (column named "mean.diff") were then estimated. We also calculated individual (recov) and mean (recov.mean) reaction norms for damselfly responses following the removal of fish kairomones in a similar manner. This data was used for analysis of behavioral plasticity of damselflies to fish predators across lakes varying in fish densities.
Code/Software
All analyses and plots were constructed in R v. 4.3.2. We used ImageJ2 software to measure damselfly head widths.
Methods
This dataset was collected from a mesocosm study paired with a field study.
In the mesocosm study, we mixed damselfly larve collected from 3 lakes in Arkansas to ensure large phenotypic variation. We randomly assigned individuals to a caged-predator or free-ranging predator treatment. The caged-predator treatment represents behavioral responses of damselflies to predator cues without direct mortality by the predator, whereas the free-ranging predator treatment represents predator selection as they were free to swim about and consume damselflies. This experiment was conducted at an outdoor mesocosm facility at the University of Arkansas. Following the duration of the experiment, we collected the remaining damselflies in each treatment and performed behavioral assays to quantify predator-induced plasticity. Head positions of damselflies were marked on an underlying grid (1cm x 1cm) every 20 minutes for a total of 3 hours. Activity rate was then calcuted by measuring the linear distances between each head position of an individual to obtain the total minimum distance moved during the assays. We measured activity rates of each individual first without the presence of predator kairomones, then with predator kairomones, and once more after the removal of predator kairomones. We took photos of the damselflies and estimated head-widths (mm) using ImageJ software to control for body size effects on activity rates. Assays were performed at a greenhouse facility at the University of Arkansas under natural lighting conditions.
In the field study, we estimated fish predator densities from lakes in Arkansas by taking three standardized seine hauls (4 x 3m) through emergent vegetation. We recorded the number of centrarchid fish in each haul and samples were averaged per lake to estimate density. We also collected damselflies at these lakes and performed the same open-field behavioral assays as described above on 20 individuals from each lake.
Data was recorded in excel and analyzed in R.