DOI: 10.5061/dryad.4mw6m90r1
title: Choosing substrates with or without predator cues by <em>Prionostemma</em> Opiliones

description: We experimentally tested for the avoidance of predator cues in an arachnid
 that relies on contact chemoreception and frequently loses its legs, the
 Neotropical Opiliones in the genus Prionostemma. First, we tested whether
 these arachnids can detect and avoid chemical cues derived from potential
 predators. When choosing between leaf litter substrates with or without
 the urine of a sympatric predator (the toad Rhinella horribilis),
 individuals preferred the substrate lacking the predator cue. Second, we
 tested that substrate choice would be affected by previous leg loss, given
 a potential reduction in sensory detection with fewer sensory organs.
 However, we found that individuals with autotomized legs were just as
 likely to avoid substrates with predator chemical cues as intact
 individuals.
description: We collected Opiliones of <em>Prionostemma</em> sp.1
 from their daytime roosting aggregations in La Selva Research Station in
 Sarapiquí, Costa Rica. We brought them to the lab and house in terraria.
 We then prepared the chemical cue of a potential predator (hereafter
 referred to as the “predator cue”), we obtained urine from one
 <em>Rhinella horribilis</em> toad the night before collecting
 Opiliones. We spread the toad's urine in leaf litter and place the
 urine-infused plant material in half of a testing arena. The other half of
 the arena was control leaf litter that was infused only in
 water.  We conducted trials in which we presented both
 stimuli (leaf litter with and without predator cues) to Opiliones. In each
 trial (n = 31), we placed five individuals in the testing arena with the
 two-stimuli setup. We placed the five individuals one by one in the center
 of one of the arenas, ensuring and confirming that each individual touched
 both the control and predator substrates at the moment of release. This
 way, we ensured that each individual was in contact with (and potentially
 aware of) both cue options from the start of the trial. We then covered
 the arena with mesh to prevent escape and permit observation. After 5
 minutes (enough time for all individuals to settle), we recorded the
 number of individuals on each substrate type, as well as the number of
 legs of each individual.
description: # Choosing substrates with or without predator cues by *Prionostemma*
 Opiliones Dataset DOI:
 [10.5061/dryad.4mw6m90r1](https://doi.org/10.5061/dryad.4mw6m90r1) ##
 Description of the data and file structure "FILE
 "OpilionesChemicalCues.csv" OVERALL DESCRIPTION: "This file
 contains the data for a lab experiment in which we explored the decision
 of roosting in a substrate with or without predator cues in an arachnid.
 We studied the Opiliones ("daddy long-legs" species of
 Prionostemma sp.1 in the lowland rainforest of Costa Rica." COLUMN
 EXPLANATION Group_ID: the identity of the group of individuals tested. A
 group of five individuals was tested simultaneously in the choice arena.
 The 5 animals were placed in a container that had half of its surface
 covered with leaf litter infused with the urine of a toad (a common
 predator of these animals). Number_of_individuals: The number of
 individuals in each trial. For this data analysis, the value is always 5
 (see the description in the paper's methods). Individual_ID: The
 unique identifier ID for each individual. Leg_condition: whether the
 animal was found with all of its eight legs = "eight_intact", or
 if it was found with less than eight legs
 "less_than_eight_autotomized". Number_of_legs: the exact number
 of legs that each animal had when found. The values range from 4 to 8.
 Choice: the substrate in which the individual chose to roost after 5
 minutes of being placed in the experimental arena. The arena had two
 substrates of leaf litter infused with either toad urine ("with
 predator cue") or with water as a control
 ("WITHOUT_predator_cue"). ## Code/software "FILE
 "DataAnalysisOpiliones.R" This file contains the R code to
 import the dataset associated with this project. The code also allows
 replicating the statistical models used and create the same graphs shown
 in the text.