DOI: 10.5061/dryad.959g2
title: Data from: Temporal variation in predation risk may explain daily rhythms of foraging behavior in an orb-weaving spider

description: Daily rhythms occur in numerous physiological and behavioral processes
 across an immense diversity of taxa, but there remain few cases in which
 mechanistic links between rhythms of trait expression and organismal
 fitness have been established. We construct a dynamic optimization model
 to determine whether risk allocation provides an adaptive explanation for
 the daily foraging rhythm observed in many species using the orb-weaving
 spider Cyclosa turbinata as a case study. Our model predicts that female
 C. turbinata should generally start foraging at lower levels of energy
 reserves (i.e., should be less bold) during midday when predators are most
 abundant. We also find that individuals' foraging efficacy determines
 whether daily rates of encounters with predators or with prey more
 strongly influences boldness under high risk. The qualitative model
 predictions are robust to variation in our parameter estimates and likely
 apply to a wide range of taxa. The predictions are also consistent with
 observed patterns of foraging behavior under both laboratory and field
 conditions. We discuss the implications of our study for understanding the
 evolution of daily rhythms and the importance of model predictions for
 interpreting empirical studies and generating additional hypotheses
 regarding behavioral evolution.
description: Observations of C.
 Turbinata foraging behavior in the fieldThese data describe 10
 days of continuous observations of the behavioral responses
 ("Event"-- attack or rest) of 9 individual female Cyclosa
 turbinata ("ID") to prey items hitting the web at different
 times of day ("TimeofDay.h").Watts_etal_FieldObservations2013.csvMetabolic Calculations for C. turbinataMetabolic calculations used to estimate the proportion of prey energy consumed per time step in the dynamic model. Includes estimates of metabolic rate for C. turbinata in microliters of oxygen per hour (Greenstone & Bennett 1980) and conversion factors from Gnaiger 1983 and Riechert 1991.Watts_etal_MetabolicCalculations2017.csvCollated Predator and Prey Abundances for C. turbinataThese data describe daily patterns in the abundances of potential predators (wasps) and prey (arthropods &lt;1.5 cm in length) of C. turbinata in the field. The data include pooled estimates of encounter rates per 3 hour interval collated from Moore et al. 2016 ("PreyTrapped", "PredatorsTrapped"), and subsequent calculations to yield encounter rates per day ("Prey.per.Day", "Pred.per.Day") and per time step ("Prey.per.t", "Pred.per.t"), as well as encounter probabilities per time step ("ProbEncPrey.per.t", "ProbEncPred.per.t").Watts_etal_CollatedPredatorPreyAbund.csvR Code for Dynamic Model of Sit-and-Wait ForagersThis file contains R code for the dynamic model used to determine whether temporal variation in predation risk favors daily patterns of foraging behavior in a sit-and-wait predator. This file was created using R v3.4.1. Additional versions of the model code (i.e., those used to plot effects of various model parameters) are available by request.Basic_model_simplepredictions.RR Code for Dynamic Model of Searching ForagersThis file contains R code for an extension of our dynamic model that considers scenarios in which foragers must actively search for prey to attack. The R code was produced in R v.3.4.1.Basic_model_searchingforprey.R