Species interactions under global change: can ecosystem processes be maintained in species assemblages with altered species composition?

据预测，全球变化将改变物种的分布。这也将不可避免地改变当地物种组合的物种组成。然而，我们目前缺乏对物种组成变化对维持当地物种组合中生态过程的影响的了解。许多关键的生态过程，如捕食、种子传播或授粉，都涉及物种之间的相互作用，在给定的生态过程中，每个物种都发挥着一定的功能作用。当地物种组合中物种组成的变化可能会扰乱物种之间的相互作用，例如由于局部灭绝，这最终可能导致失去不同的功能角色。然而，这些损失的大小取决于当地相互作用网络可以被重新连接的程度，即剩余的和/或新到达的物种是否可以接管当地灭绝物种的功能角色。在我的项目中，我建议使用来自区域种子传播系统的互惠植物-鸟类相互作用的数据集，调查物种组成的变化如何影响当地物种组合中功能角色的多样性。首先，我将使用最近建立的一种方法来评估食果鸟类在当前本地相互作用网络中的功能作用，该方法描述了物种通过觅食生态位发挥的功能作用。然后，我将对区域物种库中所有食果鸟类物种未来的潜在分布进行建模，并评估这如何影响当地物种组合中的物种组成。然后，我将根据物种的觅食生态位，在未来的物种组合中对物种之间的潜在相互作用进行建模。最后，我将调查物种组成的预期变化如何影响本地相互作用网络中功能角色的多样性，以评估物种分布的预期未来变化对种子-传播互惠关系的影响程度。物种相互作用的建模和相互作用网络的重新布线是一个相对较新的研究方向，方法学仍在发展中。因此，我的研究还涉及方法论部分，因为我的目标是改进方法论，根据物种的内在属性，即它们的功能特征，来模拟个体的相互作用。在我最近开发的一个方法论框架的基础上，我的目标是推导出一个相互作用的物种群体的特征之间的一般关系的模型。一旦建立，这种模型将有助于建立独立于经验数据和跨空间尺度的相互作用的模型，具有广泛的潜在应用，例如，将物种相互作用纳入未来物种分布的模型，并在大空间尺度上研究生态过程中的功能作用。

Global changes are predicted to alter the distribution of species. This will inevitably also change the species composition of local species assemblages. However, we currently lack an understanding of the consequences of altered species compositions for the maintenance of ecological processes in local species assemblages.Many key ecological processes, e.g. predation, seed-dispersal or pollination, involve species interactions, and within a given ecological process, each species fulfills a certain functional role. Changes in the species composition in local species assemblages might disrupt interactions between species, e.g. due to local extinctions, which could ultimately lead to the loss of distinct functional roles. The magnitude of these losses, however, depends on the degree to which a local interaction network can be re-wired, that is whether the remaining and/or newly arriving species can take over the functional roles of locally extinct species.In my project I propose to investigate how changes in species composition affect the diversity of functional roles in local species assemblages, using a dataset on mutualistic plant-bird interactions from a regional seed-dispersal system. First, I will assess the functional roles of frugivorous bird species in the current local interaction networks, using a recently established method that characterizes the functional role of species via their foraging niche. I will then model the potential future distribution of all frugivorous bird species from the regional species pool and assess how this affects the species composition in the local species assemblages. I will then model potential interactions between the species in the future species assemblages based on species' foraging niches. Finally, I will investigate how the expected future changes in species compositions affect the diversity of functional roles in the local interaction networks in order to assess the degree to which the seed-dispersal mutualism is going to be affected by the expected future changes in species distributions.The modeling of species interactions and the re-wiring of interaction networks is a relatively new line of research and the methodology is still being developed. My study therefore also involves a methodological part, as I aim to refine the methodology to model individual interactions from species intrinsic properties, i.e. their functional traits. Building upon a methodological framework that I recently developed, I aim to derive a model for general relationships between the traits of interacting species groups. Once established, such a model would facilitate the modeling of interactions independent of empirical data and across spatial scales, with a wide range of potential applications, for instance, the incorporation of species interactions into models of future species distributions and the study of functional roles in ecological processes on large spatial scales.