Houslay Thomas M, Vierbuchen Maddalena, Grimmer Andrew J, Young Andrew J, Wilson Alastair J
Centre for Ecology and Conservation University of Exeter Penryn Cornwall UK.
School of Biological & Marine Sciences Plymouth University Devon UK.
Funct Ecol. 2018 Feb;32(2):424-438. doi: 10.1111/1365-2435.12981. Epub 2017 Sep 24.
Within populations, individuals can vary in stress response, a multivariate phenomenon comprising neuroendocrine, physiological and behavioural traits.Verbal models of individual stress "coping style" have proposed that the behavioural component of this variation can be described as a single axis, with each individual's coping style being consistent across time and stress contexts.Focusing on this behavioural component of stress response and combining repeated measures of multiple traits with a novel multivariate modelling framework, we test for the existence of coping style variation and assess its stability across contexts in the Trinidadian guppy ().Specifically, we test the following hypotheses: (1) there exists repeatable among-individual behavioural (co)variation ("personality") within a mild stress context consistent with a risk-averse-risk-prone continuum of behavioural coping style, (2) there is population-level plasticity in behaviour as a function of stressor severity, (3) there is among-individual variation in plasticity (i.e. IxE), and (4) the presence of IxE reduces cross-context stability of behavioural coping style.We found significant repeatable among-individual behavioural (co)variation in the mild stress context (open field trial), represented as an matrix. However, was not readily described by a simple risk-averse-risk-prone continuum as posited by the original coping style model. We also found strong evidence for population-level changes in mean behaviour with increasing stressor severity (simulated avian and piscine predation risks).Single-trait analyses did show the presence of individual-by-environment interactions (IxE), as among-individual cross-context correlations were significantly less than +1. However, multitrait analysis revealed the consequences of this plasticity variation were minimal. Specifically, we found little evidence for changes in the structure of between mild and moderate stress contexts overall, and only minor changes between the two moderate contexts (avian vs. piscine predator).We show that a multivariate approach to assessing changes in among-individual (co)variance across contexts can prevent the over-interpretation of statistically significant, but small, individual-by-environment effects. While behavioural flexibility enables populations (and individuals) to respond rapidly to changes in the environment, multivariate personality structure can be conserved strongly across such contexts. A plain language summary is available for this article.
在种群内部，个体的应激反应会有所不同，这是一种包含神经内分泌、生理和行为特征的多变量现象。关于个体应激“应对方式”的文字模型提出，这种变异的行为成分可以被描述为一个单一轴，每个个体的应对方式在时间和应激环境中都是一致的。聚焦于应激反应的这一行为成分，并将多个特征的重复测量与一个新颖的多变量建模框架相结合，我们测试了应对方式变异的存在，并评估了其在特立尼达孔雀鱼（）不同环境中的稳定性。具体而言，我们测试了以下假设：（1）在与行为应对方式的风险规避 - 风险倾向连续体一致的轻度应激环境中，个体间存在可重复的行为（协）变异（“个性”）；（2）行为存在种群水平的可塑性，它是应激源严重程度的函数；（3）个体在可塑性方面存在变异（即个体×环境交互作用，IxE）；（4）IxE的存在会降低行为应对方式的跨环境稳定性。我们发现在轻度应激环境（旷场试验）中，个体间存在显著的可重复行为（协）变异，表现为一个矩阵。然而，它并不像原始应对方式模型所假设的那样，能轻易地用简单的风险规避 - 风险倾向连续体来描述。我们还发现了强有力的证据，表明随着应激源严重程度增加（模拟鸟类和鱼类捕食风险），种群水平的平均行为发生了变化。单性状分析确实显示了个体×环境交互作用（IxE）的存在，因为个体间的跨环境相关性显著小于 +1。然而，多性状分析表明这种可塑性变异的影响微乎其微。具体来说，我们总体上几乎没有发现轻度和中度应激环境之间矩阵结构变化的确凿证据，并且在两种中度环境（鸟类与鱼类捕食者）之间只有微小变化。我们表明，一种评估不同环境中个体间（协）方差变化的多变量方法可以防止对虽具有统计学显著性但较小的个体×环境效应进行过度解读。虽然行为灵活性使种群（和个体）能够快速响应环境变化，但多变量个性结构在这些环境中可以得到强有力的保留。本文提供了通俗易懂的总结。
