The robustness of pollination networks to the loss of species and interactions: a quantitative approach incorporating pollinator behaviourKaiser-Bunbury, C N; Muff, S; Memmott, J; Müller, C B; Caflisch, A Kaiser-Bunbury, C N; Muff, S; Müller, C B; Caflisch, A (2010). Anthropogenic disturbance, however, that promote the extinction of the strongest interactors might induce a sudden collapse of pollination networks.2

Species-rich tropical communities are expected to be more specialized than their temperate counterparts. Several studies have reported increasing biotic specialization toward the tropics, whereas others have not found latitudinal trends once accounting for sampling bias or differences in plant diversity. Thus, the direction of the latitudinal specialization gradient remains contentious. With an unprecedented global data set, we investigated how biotic specialization between plants and animal pollinators or seed dispersers is associated with latitude, past and contemporary climate, and plant diversity. We show that in contrast to expectation, biotic specialization of mutualistic networks is significantly lower at tropical than at temperate latitudes. Specialization was more closely related to contemporary climate than to past climate stability, suggesting that current conditions have a stronger effect on biotic specialization than historical community stability. Biotic specialization decreased with increasing local and regional plant diversity. This suggests that high specialization of mutualistic interactions is a response of pollinators and seed dispersers to low plant diversity. This could explain why the latitudinal specialization gradient is reversed relative to the latitudinal diversity gradient. Low mutualistic network specialization in the tropics suggests higher tolerance against extinctions in tropical than in temperate communities.

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17Land degradation results in declining biodiversity and disruption of ecosystem 18 functioning worldwide, particularly in the tropics 1 (Nectariniidae, Pycnonotidae), and three lizard species (Gekkonidae, Scincidae). 95Restoration markedly changed pollinator numbers, behaviour, performance, and 96 network structure in inselberg communities. Six to 14 months after restoration, 97 number of pollinator species was on average 21.6% higher across the four restored 98 compared to the unrestored inselbergs (Fig. 2). Monthly pollination networks showed (Fig. 2, Table1). Overall, restored networks were more generalised than 103 unrestored networks (H 2 ʹ, Fig. 2). 105The observed network responses to restoration were mirrored by the plant The observed changes in pollinator interaction behaviour and network structure had Fig. 2), which correlated with a larger total 138 fruit production (fruit crop) and higher fruit set (proportion of flowers producing fruit) 139 across the most common species (Fig. 3, Table 1). The three endemic palms (Fig. 3). Plants at restored sites had similar fruit set levels throughout the range

Co-flowering plant species commonly share flower visitors, and thus have the potential to influence each other's pollination. In this study we analysed 750 quantitative plant-pollinator networks from 28 studies representing diverse biomes worldwide. We show that the potential for one plant species to influence another indirectly via shared pollinators was greater for plants whose resources were more abundant (higher floral unit number and nectar sugar content) and more accessible. The potential indirect influence was also stronger between phylogenetically closer plant species and was independent of plant geographic origin (native vs. non-native). The positive effect of nectar sugar content and phylogenetic proximity was much more accentuated for bees than for other groups. Consequently, the impact of these factors depends on the pollination mode of plants, e.g. bee or fly pollinated. Our findings may help predict which plant species have the greatest importance in the functioning of plant-pollination networks.