DOI: 10.5061/dryad.xksn02vw0
title: Resource gradients create energy trade-offs in the inducible defense response of <em>Paramecium aurelia</em>

description: Ecological communities are structured by inter- and intraspecific
 interactions. The stability of communities is governed by the strength and
 number of species interactions. Therefore, mechanisms that act to decrease
 the interaction strength between species are thought to stabilize
 communities. One proposed stabilizing mechanism is the inducible defenses
 of prey. Inducible defenses are morphological and behavioral traits only
 expressed in the presence of a predator or under perceived predation
 threat. By creating a population of prey that is less susceptible to
 predation, inducible defenses reduce interaction strength between
 predators and prey. In this study, we evaluated the expression of an
 inducible defense in the protozoan, Paramecium aurelia, along two
 environmental gradients (perceived predation threat and basal nutrients)
 and for three clonal populations of P. aurelia. The three clonal
 populations display a range in expression of one morphological defense
 (i.e., increase in body width), with one population expected to display an
 inducible defense, one expected to remain in a permanently defended state,
 and one expected to remain in a permanently undefended state. We found
 that for the clone that displays an inducible defense, there was a
 tradeoff in energy expenditure that occurred at around 30 predators, in
 which protists in high nutrient concentrations were narrower than protists
 in low nutrient conditions, despite additional resources. These results
 indicate either that there are potential costs to inducible defenses or
 that energy gained from increased nutrients was being diverted elsewhere,
 such as for reproduction or maintenance. Additionally, for all three
 clonal populations, protist width approached an asymptote of max width at
 the highest nutrient concentrations, suggesting a diminishing or maximal
 benefit of protist width even if a tradeoff did not occur. In all, the
 results from our study provide information on the potential limits to the
 benefits of inducible defenses along two environmental gradients, and both
 bottom-up and top-down pressures interact to significantly affect the
 response of prey in predator-prey interactions. With an increased
 understanding of how bottom-up and top-down pressures are affecting
 species interactions, we can better predict changes in community
 composition and stability under changing environmental conditions.
description: # Data For: Resource gradients create energy trade-offs in the inducible
 defense response of *Paramecium aurelia* Dataset DOI:
 [10.5061/dryad.xksn02vw0](https://doi.org/10.5061/dryad.xksn02vw0) ##
 Description of the data and file structure In this study, we evaluated the
 expression of an inducible defense in the protozoan, *Paramecium aurelia*,
 along two environmental gradients (perceived predation threat and basal
 nutrients) and for three clonal populations of *P. aurelia*. The three
 clonal populations display a range in expression of one morphological
 defense (i.e., increase in body width), with one population expected to
 display an inducible defense, one expected to remain in a permanently
 defended state, and one expected to remain in a permanently undefended
 state. The study included a 6x8 full factorial design with six nutrient
 treatments and eight predator treatments that was replicated 10 times. We
 measured the length and width of 3-4 randomly chosen protists within each
 treatment combination. Data include the treatment combinations (i.e.,
 Predator and Nutrient), data structure (i.e., Plate, Well, Replicate),
 protist ID (i.e., A, B, or C), protist length and width (measured in
 micrometers), and the length:width ratio.  ### Files and variables ####
 File: DataforMcClureandHammill2025.csv **Description:** Data on the length
 and widths of protists under varying nutrient and predator treatments. The
 study included a 6x8 full factorial design with 10 complete replicates.
 Experiments lasted 24 hours.  **NOTE:** NAs in the csv file are stand-in
 values for protists that were not measured for a given treatment
 combination. Additional photos of protists were taken if the photo quality
 was not clear (due to growth in the treatment media); however, given that
 some treatment combinations had a 4th protist measurement and some did
 not, we included the 'NA' to indicate this lack of 4th protist
 photo. These are indicated by the letter 'D' in the *Protist*
 column. The NA values are there to demonstrate that the 4th photo was not
 needed for that treatment.  Blank values in the width, length, and L:W
 columns are for replicate #6. The microscope settings for this replicate
 were not set correctly for several of the treatment combinations, and
 therefore, this replicate was removed from the study but remains in the
 attached data. These blanks are true NA values.  ##### Variables * Full
 ID: Name of the image file for each protist photo that was taken. *
 Predator: This is the predator treatment. Values include 1, 3, 5, 10, 15,
 20, 40, and 60 predators. * Nutrient: This is the basal nutrient
 treatment. Values include 0.03, 0.07, 0.15, 0.30, 0.60, and 0.80 g (grams
 of protist pellet) * Plate: This is the 24-well plate identifier (1 or 2).
 Because the treatments were randomly assigned to a well on one of two
 24-well plates, and for statistical structure in our analysis, we needed
 to include this column in the data. * Well: This is the well number across
 two 24-well plates (i.e., 48 total) randomly assigned to the treatment
 combination. Because the treatments were randomly assigned to a well on
 one of two 24-well plates, and for statistical structure in our analysis,
 we needed to include this column in the data. * Rep: This is the replicate
 number. Values include 1-10. Two additional replicates were included (11
 and 12) but not used for the analysis in the accompanying paper. *
 Protist: This is the protist identification value (e.g., A, B, C, or D).
 Three or four protists were randomly selected from the treatment well and
 measured based on photos. Some treatments include a fourth protist due to
 the poor photo quality in these wells. The fourth protist was included for
 these wells to ensure an accurate representation of the populations within
 that treatment. * Width: Width of the protist measured in micrometers. *
 Length: Length of the protist measured in micrometers. * L:W_Ratio: The
 length:width ratio of the protist calculated using the length and width
 values above.  * Clone: This is the clonal line of the protist. Clone
 ‘AUR’ is expected to display a morphological inducible response under
 predation threat (i.e., changes width based on the level of predation
 threat). Clone ‘FD4’ is ‘permanently expressed’ in that it is expected to
 remain in a wide physical state regardless of the level of predation
 threat. Clone ‘EV2’ does not display a morphological inducible defense
 (i.e., it is expected to remain in a narrower physical state regardless of
 predation threat). ## Code/software R-4.5.2 and R Studio ## Access
 information Other publicly accessible locations of the data: * None Data
 was derived from the following sources: * None