DOI: 10.5061/dryad.1g1jwstzd
title: Data and Rscripts from: An integrated experimental and mathematical approach to inferring the role of food exploitation and interference interactions in shaping life history

description: Intraspecific interactions can occur through many ways but the mechanisms
 can be broadly categorized as food exploitation and interference
 interactions. Identifying how intraspecific interactions impact life
 history is crucial to accurately predict how population density and
 structure influence dynamics. However, disentangling the effects of
 interference interactions from exploitation using experiments, is
 challenging for most biological systems. Here we propose an approach that
 combines experiments with modeling to infer the pathways of intraspecific
 interactions in a system. First, a consumer-resource model is built
 without intraspecific interactions. Then, the model is parameterized by
 fitting it to life-history data from a first experiment in which food
 abundance was varied. Next, hypothesized scenarios of intraspecific
 interactions are incorporated into the model which is then used to predict
 life histories with increasing competitor density. Lastly, model
 predictions are compared against data from a second experiment which
 raised groups of competitors of different densities. This comparison
 allows us to infer the role of interference and exploitation in shaping
 life history. We demonstrated the approach using the smaller tea tortrix
 Adoxophyes honmai across a range of temperature. We investigated five
 scenarios of interactions that included exploitation and three pathways
 for interference through some effects either on energetics to represent
 changes in ingestion or activity, or on mortality to model deadly
 interactions, or on mortality and ingestion to model cannibalism. Overall,
 intraspecific interactions in tea tortrix are best explained by a high
 level of deadly interactions along with some level of interference that
 acts on energy such as escaping and blocking access to food. Deadly
 interactions increase with temperature while interference that acts on
 energy is strongest close to the optimal temperature for reproduction.
 Interestingly, exploitation is more important than interference at low
 competitor density. The combination of mathematical modeling and
 experimentation allowed us to mechanistically characterize the
 intraspecific interactions in tea tortrix in a way that is readily
 incorporated into population-level mathematical models. The primary value
 of this approach, however, is that it can be applied to a much wider range
 of taxa than is possible with pure experimental approaches.
description: We designed an approach to infer the most likely pathways of
 intraspecific interactions that shape life histories in a studied system.
 The approach is in four steps that weave together theory and experiments.
 We demonstrated the approach with the smaller tea tortrix moth
 (<em>Adoxophies honmai</em>).
 <strong>Step
 1. Build base model</strong> We
 first built the base model which is the baseline for the theoretical
 framework used later to predict how different pathways of intraspecific
 interactions influence life histories. The base model is a
 consumer-resource cohort model that assumes no intraspecific interactions
 – no food exploitation and no interference interactions. As such, the base
 model describes solely how vital rates are impacted by changes in food
 abundance. <strong>Step 2. Parameterize base
 model (provided R script: Step2.r)</strong> Most
 model parameters can be directly estimated from independent data but a few
 remained unknown. Unknown parameters were estimated by fitting the base
 model to the observed life-history traits in the food experiment
 <strong>(FoodExperiment.csv)</strong>. The food experiment
 raised individuals in the absence of intraspecific interactions and
 exposed them to a wide range of food abundance.
 <strong>Step 3. Incorporate intraspecific interactions in
 base model to predict their effects on life histories (provided R script:
 Step3.r)</strong> In this step, the parameterized
 base model was modified to incorporate several hypothesized scenarios of
 intraspecific interactions. For each scenario, we predicted how
 intraspecific interactions impact life-history traits and stage-structure
 distributions for groups of competitors. 
 <strong>Step 4. Test model predictions using
 experiment </strong> To evaluate the support for
 each hypothesis, we compared model predictions with data from the
 competition experiment
 <strong>(CompetitionExperiment.csv)</strong>. The competition
 experiment measured the impact of intraspecific interactions (i.e.
 competitor density) on life-history traits and on the stage-structure of
 groups of competitors. The comparison of life-history data from experiment
 with model predictions allowed to infer the role of interference
 interactions and the one of food exploitation in shaping life histories,
 as well as the functional dependencies for interference interactions in
 the studied system.
description: Please refer to ReadMe file.