Jedlikowski Jan, Brambilla Mattia
Faculty of Biology, Biological and Chemical Research Centre, University of Warsaw , Warsaw , Poland.
Settore Biodiversità e Aree protette, Fondazione Lombardia per l'Ambiente, Seveso (MB), Italy; Sezione Zoologia dei Vertebrati, Museo delle Scienze, Trento, Italy.
PeerJ. 2017 Mar 28;5:e3164. doi: 10.7717/peerj.3164. eCollection 2017.
Habitat selection and its adaptive outcomes are crucial features for animal life-history strategies. Nevertheless, congruence between habitat preferences and breeding success has been rarely demonstrated, which may result from the single-scale evaluation of animal choices. As habitat selection is a complex multi-scale process in many groups of animal species, investigating adaptiveness of habitat selection in a multi-scale framework is crucial. In this study, we explore whether habitat preferences acting at different spatial scales enhance the fitness of bird species, and check the appropriateness of single vs. multi-scale models. We expected that variables found to be more important for habitat selection at individual scale(s), would coherently play a major role in affecting nest survival at the same scale(s).
We considered habitat preferences of two Rallidae species, little crake () and water rail (), at three spatial scales (landscape, territory, and nest-site) and related them to nest survival. Single-scale versus multi-scale models (GLS and glmmPQL) were compared to check which model better described adaptiveness of habitat preferences. Consistency between the effect of variables on habitat selection and on nest survival was checked to investigate their adaptive value.
In both species, multi-scale models for nest survival were more supported than single-scale ones. In little crake, the multi-scale model indicated vegetation density and water depth at the territory scale, as well as vegetation height at nest-site scale, as the most important variables. The first two variables were among the most important for nest survival and habitat selection, and the coherent effects suggested the adaptive value of habitat preferences. In water rail, the multi-scale model of nest survival showed vegetation density at territory scale and extent of emergent vegetation within landscape scale as the most important ones, although we found a consistent effect with the habitat selection model (and hence evidence for adaptiveness) only for the former.
Our work suggests caution when interpreting adaptiveness of habitat preferences at a single spatial scale because such an approach may under- or over-estimate the importance of habitat factors. As an example, we found evidence only for a weak effect of water depth at territory scale on little crake nest survival; however, according to the multi-scale analysis, such effect turned out to be important and appeared highly adaptive. Therefore, multi-scale approaches to the study of adaptive explanations for habitat selection mechanisms should be promoted.
栖息地选择及其适应性结果是动物生活史策略的关键特征。然而，栖息地偏好与繁殖成功率之间的一致性很少得到证实，这可能是由于对动物选择的单尺度评估所致。由于栖息地选择在许多动物物种群体中是一个复杂的多尺度过程，在多尺度框架下研究栖息地选择的适应性至关重要。在本研究中，我们探讨了在不同空间尺度上起作用的栖息地偏好是否能提高鸟类的适合度，并检验单尺度模型与多尺度模型的适用性。我们预期，在个体尺度上对栖息地选择更为重要的变量，会在相同尺度上对巢存活率产生一致的主要影响。
我们考虑了秧鸡科两种鸟类，即姬田鸡（）和水秧鸡（）在三个空间尺度（景观、领地和巢址）上的栖息地偏好，并将它们与巢存活率相关联。比较了单尺度模型与多尺度模型（广义最小二乘法和广义线性混合模型），以检验哪种模型能更好地描述栖息地偏好的适应性。检验变量对栖息地选择和巢存活率的影响之间的一致性，以研究它们的适应价值。
在这两个物种中，巢存活率的多尺度模型比单尺度模型得到了更多支持。在姬田鸡中，多尺度模型表明领地尺度上的植被密度和水深，以及巢址尺度上的植被高度是最重要的变量。前两个变量是对巢存活率和栖息地选择最重要的变量之一，且一致的影响表明了栖息地偏好的适应价值。在水秧鸡中，巢存活率的多尺度模型显示领地尺度上的植被密度和景观尺度上挺水植被的范围是最重要的变量，尽管我们仅发现前者与栖息地选择模型有一致的影响（因此有适应性的证据）。
我们的研究表明，在解释单一空间尺度上栖息地偏好的适应性时应谨慎，因为这种方法可能会低估或高估栖息地因素的重要性。例如，我们仅发现领地尺度上的水深对姬田鸡巢存活率的影响较弱；然而，根据多尺度分析，这种影响变得很重要且具有高度适应性。因此，应推广多尺度方法来研究栖息地选择机制的适应性解释。
