Functional Ecology ( IF 4.6 ) Pub Date : 2022-08-11 , DOI: 10.1111/1365-2435.14160 Amparo Lázaro 1, 2 , Carmelo Gómez‐Martínez 1
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1 INTRODUCTION
Plant-pollinator interaction networks are not static but have their own temporal dynamics. Understanding how these temporal dynamics respond to human-driven disturbances is necessary to predict and mitigate the consequences of global change on pollination interactions and ecosystem functioning (CaraDonna et al., 2021). Several authors (Novotny, 2009; Poisot et al., 2012) have developed methods to understand the dynamics of interaction networks by estimating interaction turnover and its components: changes in species composition (species turnover) and reassembly of interactions among species (rewiring). These methods have been applied to the study of spatial (e.g. Simanonok & Burkle, 2014; Trøjelsgaard et al., 2015) and temporal (inter-annual, within-season; e.g. Arroyo-Correa et al., 2020; CaraDonna et al., 2017; Simanonok & Burkle, 2014) variation in interaction patterns with different objectives. Despite this, we still know very little about the conditions that make species more likely to rewire (Burkle et al., 2016).
Here we hypothesize that greater interaction rewiring in plant-pollinator networks may be expected in more disturbed landscapes (Figure 1a), because these landscapes hold a higher proportion of generalist species (Aizen et al., 2012; Burkle & Knight, 2012; Cagnolo et al., 2009; Gómez-Martínez et al., 2020) able to use different partners (Aizen et al., 2012; Burkle & Knight, 2012). In addition, the scarcity of local flowering resources, often associated with highly disturbed habitats (Winfree et al., 2011), can make insect species less choosy at the time of selecting partners (Lázaro et al., 2013) and reduce niche segregation among pollinators (Gómez-Martínez et al., 2022). Diet adjustments of generalist pollinators to adapt to flower availability (Gómez-Martínez et al., 2022; Kelly & Elle, 2021) and new contexts of competence with other pollinators (Hallett et al., 2017; Inouye, 1978) may favour rewiring in disturbed landscapes. Moreover, anthropogenic disturbances may act as strong environmental filters leading to the functional homogenization of communities at the regional level (Clavel et al., 2011; Gossner et al., 2016), which may also favour pollinator-sharing (Carvalheiro et al., 2014). All these features may result in higher interaction rewiring as landscapes lose natural habitats (Figure 1b). On the contrary, sites surrounded by larger natural areas may hold a higher number of species (González-Varo et al., 2009; Malavasi et al., 2018), particularly of specialist ones (Aizen et al., 2012; Burkle & Knight, 2012; Cagnolo et al., 2009); and landscape complementation (Dunning et al., 1992) and connectivity (Horváth et al., 2019) in those conserved areas may help enhance species movements between patches. However, understanding how partner-switching vary along geographic gradients still remains as a major challenge in ecology (Burkle et al., 2016).
The extent of rewiring along gradients of habitat loss might affect the resulting static interaction structures at the community level (Figure 1c). Indeed, previous work reported a relationship between the temporal replacement of species and modularity in networks that are phenologically structured (Morente-López et al., 2018). Also, Schwarz et al. (2020) showed that there is an interplay between sampling effort and temporal dynamics that shapes network structure across different temporal scales. However, it is still unclear the extent to which seasonal interaction rewiring influences the structure of static networks built by accumulating interactions through the season, which is still the most common way of analysing network structure and is supposed to be related to the stability and robustness of communities (Bascompte et al., 2006; Krause et al., 2003; Lázaro et al., 2022; Tylianakis et al., 2010). In addition, determining the species more prone to rewiring may help to comprehend how future anthropogenic changes will affect the interactions and functioning of communities. The maintenance of ecosystems services might depend on the capacity of generalist species of switching partners in a global change scenario (Bartley et al., 2019). It could be predicted that species' probability of rewiring increases as their generalization level and abundance increase (Figure 1d), because these variables are normally associated with more and stronger interactions (Vázquez et al., 2007). Indeed, some previous studies have shown increased rewiring in more generalist species (Olesen et al., 2011). However, the extent to which the abundance and specialization of species in communities affect their rewiring might vary along disturbance gradients, because the importance of population features and behavioural traits defining plant-pollination interactions is known to be context-dependent (e.g. Lázaro et al., 2013).
In this study, we aimed at evaluating the hypothesis that habitat loss is related to an increase in seasonal (i.e. within-year) interaction rewiring in plant-pollinator communities (Figure 1a), impacting the functional structure of communities. For that, we sampled pollination interactions in 20 wild Olea europaea communities along a gradient of habitat loss (estimated using the percentage of natural areas surrounding the communities) and tested the following three predictions: (1) as the percentage of natural habitat in the landscape decreases, interaction rewiring may increase (Figure 1b) (2) as seasonal interaction rewiring increases, the static cumulative structure of networks may become less specialized and nested (Figure 1c), because niche segregation may decrease, and; (3) more generalist and abundant species may be more prone to rewiring (Figure 1d), but the effect may be stronger in landscapes with a low percentage of natural areas where more species are expected to rewire.
中文翻译：
栖息地丧失增加了植物 - 传粉者网络中的季节性相互作用重新布线
1 简介
植物 - 传粉者相互作用网络不是静态的，而是有自己的时间动态。了解这些时间动态如何响应人为干扰对于预测和减轻全球变化对授粉相互作用和生态系统功能的影响是必要的（CaraDonna 等人， 2021 年）。几位作者（Novotny， 2009 年；Poisot 等人， 2012 年）开发了通过估计相互作用周转及其组成部分来理解相互作用网络动态的方法：物种组成的变化（物种周转）和物种间相互作用的重组（重新布线）。这些方法已应用于空间研究（例如 Simanonok & Burkle, 2014 ; Trøjelsgaard et al., 2015) 和时间（年际、季节内；例如 Arroyo-Correa 等人， 2020 年；CaraDonna 等人， 2017 年；Simanok 和 Burkle， 2014 年）不同目标的交互模式的变化。尽管如此，我们仍然对使物种更有可能重新布线的条件知之甚少（Burkle 等人， 2016 年）。
在这里，我们假设在更受干扰的景观中可能预期植物-传粉者网络中更大的相互作用重新布线（图 1a），因为这些景观拥有更高比例的通才物种（Aizen 等， 2012；Burkle & Knight， 2012；Cagnolo 等al., 2009 ; Gómez-Martínez et al., 2020 ) 能够使用不同的合作伙伴 (Aizen et al., 2012 ; Burkle & Knight, 2012 )。此外，当地开花资源的稀缺，通常与高度扰乱的栖息地有关（Winfree 等人， 2011 年），可以使昆虫物种在选择伙伴时不那么挑剔（Lázaro 等人， 2013 年）) 并减少传粉媒介之间的生态位隔离（Gómez-Martínez 等人， 2022 年）。通才授粉者的饮食调整以适应花卉可用性（Gómez-Martínez 等人， 2022 年；Kelly 和 Elle， 2021 年）和其他授粉者能力的新背景（Hallett 等人， 2017 年；Inouye， 1978 年）可能有利于重新布线扰乱的风景。此外，人为干扰可能充当强大的环境过滤器，导致区域层面社区的功能同质化（Clavel 等人， 2011 年；Gossner 等人， 2016 年），这也可能有利于传粉媒介共享（Carvalheiro 等人， 2014）。随着景观失去自然栖息地，所有这些特征都可能导致更高的交互重新布线（图 1b）。相反，被更大的自然区域包围的地点可能拥有更多的物种（González-Varo et al., 2009 ; Malavasi et al., 2018），尤其是专业物种（Aizen et al., 2012 ; Burkle & Knight） , 2012 ; Cagnolo 等人, 2009 ); 景观互补 (Dunning et al., 1992 ) 和连通性 (Horváth et al., 2019) 在这些保护区可能有助于加强斑块之间的物种迁移。然而，了解伴侣转换如何随地理梯度变化仍然是生态学中的一项重大挑战（Burkle 等人， 2016 年）。
沿栖息地丧失梯度重新布线的程度可能会影响社区层面产生的静态相互作用结构（图 1c）。事实上，以前的工作报告了物种的时间替换与物候结构网络中的模块性之间的关系（Morente-López 等人， 2018 年）。此外，施瓦茨等人。( 2020) 表明采样努力和时间动态之间存在相互作用，这些时间动态在不同的时间尺度上形成网络结构。然而，季节性交互重构对通过季节累积交互构建的静态网络结构的影响程度尚不清楚，这仍然是分析网络结构的最常用方法，应该与网络的稳定性和鲁棒性有关。社区（Bascompte 等人， 2006 年；Krause 等人， 2003 年；Lázaro 等人， 2022 年；Tylianakis 等人， 2010 年）。此外，确定更容易重新布线的物种可能有助于理解未来的人为变化将如何影响社区的相互作用和功能。生态系统服务的维持可能取决于全球变化情景中转换伙伴的通才物种的能力（Bartley 等人， 2019 年）。可以预测，随着泛化水平和丰度的增加，物种重新布线的概率会增加（图 1d），因为这些变量通常与更多和更强的相互作用相关（Vázquez 等人， 2007 年）。事实上，之前的一些研究表明，在更通才的物种中重新布线会增加（Olesen et al., 2011）。然而，群落中物种的丰度和专业化对其重新布线的影响程度可能会随着干扰梯度而变化，因为已知定义植物授粉相互作用的种群特征和行为特征的重要性取决于环境（例如 Lázaro 等人。 , 2013 年）。
在这项研究中，我们旨在评估栖息地丧失与植物-传粉媒介群落中季节性（即年内）相互作用重新布线增加有关的假设（图 1a），从而影响群落的功能结构。为此，我们对 20 个野生油橄榄的授粉相互作用进行了采样沿栖息地丧失梯度的社区（使用社区周围自然区域的百分比估计）并测试了以下三个预测：（1）随着景观中自然栖息地的百分比减少，相互作用重新布线可能会增加（图 1b）（2 ）随着季节性交互重新布线的增加，网络的静态累积结构可能变得不那么专业化和嵌套（图 1c），因为生态位隔离可能会减少，并且；(3) 更通才和丰富的物种可能更容易重新布线（图 1d），但在自然区域比例较低的景观中，预计会有更多物种重新布线，这种影响可能更强。
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