1. Pollen limitation may be a consequence of changes in pollinator abundance, diversity and identity. However, no empirical evidence exists concerning the consequences that the spatial variation in pollinator fauna has on pollen limitation intensity and plant reproduction. In this study, we test the effect that changes in flower-visitor abundance, diversity and identity exert on the occurrence and strength of pollen limitation by experimentally quantifying pollen limitation in eight populations of Erysimummediohispanicum, a pollination-generalist plant native to the Iberian Peninsula. 2. Pollen limitation was accounted for by using a comprehensive estimator, the net reproductive rate (R0). Nevertheless, we also determined which components of plant reproduction, from ovule fertilization to seedling survival, were more intensely pollen-limited. Finally, we explored whether the spatial variation in pollen limitation intensity was related to among-population changes in flower-visitor abundance, diversity and identity. 3. The whole reproductive cycle of E. mediohispanicum was pollen-limited, although pollen limitation occurred more strongly during the ovule fertilization and seed-production phases than during fruit ripening or seedling emergence and establishment. 4. There was a significant among-population difference in pollen limitation intensity. Pollen limitation strength was associated with variations in flower-visitor diversity, and identity. Populations with lower flower-visitor diversity and with many low-efficiency pollinators (i.e. beetles) showed stronger pollen limitation. 5. Synthesis. Our study shows that the intensity of pollen limitation at the population level may depend on several characteristics of the assemblage of flower-visiting insects, such as their abundance, diversity and identity. Our results suggest that any impoverishment of pollinator diversity or any alteration in the specific composition of the pollinator assemblage may exacerbate pollen limitation.

Interdisciplinarity is needed to gain knowledge of the ecology of invasive species and invaded ecosystems, and of the human dimensions of biological invasions. We combine a quantitative literature review with a qualitative historical narrative to document the progress of interdisciplinarity in invasion science since 1950. Our review shows that 92.4% of interdisciplinary publications (out of 9192) focus on ecological questions, 4.4% on social ones, and 3.2% on social-ecological ones. The emergence of invasion science out of ecology might explain why interdisciplinarity has remained mostly within the natural sciences. Nevertheless, invasion science is attracting social-ecological collaborations to understand ecological challenges, and to develop novel approaches to address new ideas, concepts, and invasion-related questions between scholars and stakeholders. We discuss ways to reframe invasion science as a field centred on interlinked socialecological dynamics to bring science, governance and society together in a common effort to deal with invasions.

The Geographic Mosaic Theory of Coevolution predicts the occurrence of mosaics of interaction-mediated local adaptations and maladaptations. Empirical support to this prediction has come mostly from specialist interactions. In contrast, local adaptation is considered highly unlikely in generalist interactions. In this study, we experimentally test local adaptation in a generalist plant-pollinator geographic mosaic, by means of a transplant experiment in which plants coming from two evolutionary hotspots and two coldspots were offered to pollinators at the same four localities. Plants produced in the hotspots attracted more pollinators in all populations, whereas coldspot plants attracted fewer pollinators in all populations. Differences in adaptation were not related to genetic similarity between populations, suggesting that it was mainly due to spatial variation in previous selective regimes. Our experiment provides the first strong support for a spatially structured pattern of adaptation and maladaptation generated by a generalist free-living mutualism.

It is conjectured that the geographic variation in pollination niches has contributed to the observed floral divergence in E. mediohispanicum. The process mediating this floral divergence presumably has been adaptive wandering, but the adaptation to the local pollinator faunas has been not universal. The outcome is a landscape where a few populations locally adapted to their pollination environment (generalist pollination ecotypes) coexist with many populations where this local adaptation has failed and where the plant phenotype is not primarily shaped by pollinators.

SummaryIt is widely assumed that floral diversification occurs by adaptive shifts between pollination niches. In contrast to specialized flowers, identifying pollination niches of generalist flowers is a challenge. Consequently, how generalist pollination niches evolve is largely unknown.We apply tools from network theory and comparative methods to investigate the evolution of pollination niches among generalist species belonging to the genus Erysimum. These species have similar flowers.We found that the studied species may be grouped in several multidimensional niches separated not by a shift of pollinators, but instead by quantitative variation in the relative abundance of pollinator functional groups. These pollination niches did not vary in generalization degree; we did not find any evolutionary trend toward specialization within the studied clade. Furthermore, the evolution of pollination niche fitted to a Brownian motion model without phylogenetic signal, and was characterized by frequent events of niche convergences and divergences.We presume that the evolution of Erysimum pollination niches has occurred mostly by recurrent shifts between slightly different generalized pollinator assemblages varying spatially as a mosaic and without any change in specialization degree. Most changes in pollination niches do not prompt floral divergence, a reason why adaptation to pollinators is uncommon in generalist plants.