Data and Rscripts from: An integrated experimental and mathematical approach to inferring the role of food exploitation and interference interactions in shaping life history

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.

种内相互作用（intraspecific interactions）可通过多种方式发生，但其机制大致可分为食物掠夺（food exploitation）和干扰相互作用（interference interactions）两类。明确种内相互作用如何影响生活史（life history），对于准确预测种群密度和结构如何影响动态至关重要。然而，对于大多数生物系统而言，通过实验区分干扰相互作用与掠夺作用的效应具有挑战性。本文提出一种实验与建模相结合的方法，以推断某一系统中种内相互作用的路径。首先，构建不含种内相互作用的消费者-资源模型（consumer-resource model）；随后，通过将模型拟合至首个实验的生活史数据（该实验中食物丰度被改变）来对模型进行参数化；接着，将种内相互作用的假设情景纳入模型，并用其预测竞争者密度增加时的生活史；最后，将模型预测结果与第二个实验的数据（该实验饲养了不同密度的竞争者群体）进行比较。这种比较使我们能够推断干扰和掠夺在塑造生活史中的作用。我们通过茶小卷叶蛾（smaller tea tortrix，Adoxophyes honmai）在不同温度下的实验验证了该方法。我们研究了五种相互作用情景，包括掠夺作用以及三种干扰路径——通过对能量学的影响（代表摄食或活动的变化）、对死亡率的影响（模拟致命相互作用），或同时对死亡率和摄食的影响（模拟同类相食）。总体而言，茶小卷叶蛾的种内相互作用可通过高水平的致命相互作用以及一定程度的能量干扰（如逃避和阻碍食物获取）得到最佳解释。致命相互作用随温度升高而增加，而能量干扰在接近繁殖最适温度时最强。有趣的是，在低竞争者密度下，掠夺作用比干扰作用更重要。数学建模与实验的结合使我们能够从机制上表征茶小卷叶蛾的种内相互作用，且这种表征方式易于纳入种群水平的数学模型。然而，该方法的主要价值在于，它可应用于比纯实验方法更广泛的类群。