DOI: 10.5061/dryad.bg79cnpj2
title: Data from: Predators drive selection for adaptive plasticity in prey defense behavior

description: 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.
description: 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. 
description: # 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.