Behavioural Ecology, Department of Biology, Ludwig Maximilians University of Munich, Planegg-Martinsried, Germany.
Federal Maritime and Hydrographic Agency, Department Management of the Sea, Division Assessment and Monitoring, Section Environmental Assessment, Rostock, Germany.
J Anim Ecol. 2023 Sep;92(9):1707-1718. doi: 10.1111/1365-2656.13966. Epub 2023 Jun 15.
A major question in behavioural ecology is why behaviour, physiology and morphology are often integrated into syndromes. In great tits, Parus major, for example, explorative males are larger (vs. smaller) and leaner (vs. heavier) compared to less explorative individuals. Unfortunately, considerable debate exists on whether patterns found in specific studies are replicable. This debate calls for study replication among species, populations and sexes. We measured behavioural (exploration), physiological (breathing rate) and morphological traits (body mass, tarsus length, wing length, bill length) in two species (great vs. blue tits Cyanistes caeruleus), two populations (Forstenrieder Park vs. Starnberg) and two sexes (males vs. females). We then tested whether the same pattern of integration characterized all unique combinations of these three biological categories (hereafter called datasets). We used a multi-year repeated measures set-up to estimate among-individual trait correlation matrices for each dataset. We then used structural equation modelling to test for size-dependent behaviour and physiology, size-corrected (i.e. size-independent) behaviour-physiology correlations and size-corrected body mass-dependent behaviour and physiology. Finally, we used meta-analyses to test which structural paths were generally (vs. conditionally) supported (vs. unsupported). We found general and consistent support for size-dependent physiology and size-corrected body mass-dependent physiology across datasets: faster breathers were smaller but heavier for their size. Unexpectedly, condition-dependent behaviour was not supported: explorative birds were neither leaner, nor was this relationship heterogeneous across datasets. All other hypothesized patterns were dataset-specific: the covariance between size and behaviour, and between behaviour and physiology differed in sign between datasets, and both were, on average, not supported. This heterogeneity was not explained by any of our moderators: species, population or sex. The specific pattern of size- and condition-dependent physiology reported for a unique combination of species, population, and sex, thus generally predicted those in others. Patterns of size- or condition-dependent behaviour (i.e. 'personality'), or behaviour-physiology syndromes reported in specific datasets, by contrast, did not. These findings call for studies revealing the ecological background of this variation and highlight the value of study replication to help understand whether patterns of phenotypic integration reported in one study can be generalized.
行为生态学中的一个主要问题是，为什么行为、生理和形态通常会整合为综合征。例如，在大山雀 Parus major 中，探索性更强的雄性比探索性较弱的雄性体型更大（更小）、更瘦（更胖）。不幸的是，关于特定研究中发现的模式是否具有可重复性，存在着相当大的争议。这种争论呼吁在物种、种群和性别之间进行研究复制。我们在两个物种（大山雀与蓝山雀 Cyanistes caeruleus）、两个种群（福斯滕费尔德公园与施塔恩贝格）和两个性别（雄性与雌性）中测量了行为（探索）、生理（呼吸率）和形态特征（体重、跗跖长、翼长、喙长）。然后，我们检验了所有这三个生物类别（以下简称数据集）的独特组合是否具有相同的整合模式。我们使用多年重复测量的设置来估计每个数据集的个体特征相关矩阵。然后，我们使用结构方程模型来检验与体型相关的行为和生理、体型校正（即体型独立）的行为-生理相关性以及体型校正的体重相关的行为和生理。最后，我们使用元分析来检验哪些结构路径普遍（条件）支持（不支持）。我们发现，与体型相关的生理和体型校正的体重相关的生理在所有数据集之间具有普遍而一致的支持：呼吸更快的动物体型更小，但相对体重更重。出乎意料的是，条件相关的行为没有得到支持：探索性更强的鸟类既不更瘦，而且这种关系在数据集之间也没有异质性。所有其他假设的模式都是数据集特有的：体型与行为之间以及行为与生理之间的协方差在数据集之间的符号不同，而且平均来说，这些模式都没有得到支持。这种异质性不能用我们的任何调节剂来解释：物种、种群或性别。因此，为一个物种、种群和性别的独特组合报告的与体型和条件相关的生理的特定模式，通常可以预测其他组合的模式。相反，在特定数据集中报告的与体型或条件相关的行为（即“个性”）或行为-生理综合征模式则不能。这些发现呼吁开展研究揭示这种变异的生态背景，并强调研究复制的价值，以帮助理解在一项研究中报告的表型整合模式是否可以推广。
