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Cactus flowers have traditionally been considered to be specialized to certain pollination guilds, but pollination studies reveal that most species are actually generalists. This suggests that floral traits are not always predictive of the animal visitors that pollinate cactus flowers. Here, we studied the pollination of Echinopsis leucantha (Gillies ex Salm-Dyck) Walp., an endemic cactus of Argentina, whose floral traits would suggest that it is pollinated by moths. The floral lifespan and flower availability throughout the reproductive period were evaluated. Field experiments were carried out to study the reproductive system and the identity and effectiveness of floral visitors. Echinopsis leucantha flowers had a nocturnal anthesis time that extended into the following morning. The species was self-incompatible. Floral visitors included moths, bees, and passerine birds. However, diurnal visitors were more effective as pollinators than nocturnal ones. The flowers of E. leucantha were phenotypically specialized (sphingophily); however, the pollination system was functionally and ecologically generalized. The results confirm that generalized pollination systems are widespread among species of the Echinopsis genus with nocturnal flowers, for which diurnal pollinators seem to have a key role in fruit and seed production. Our study constitutes the first record of passerine bird pollination in the Cactaceae for mainland South America. Keywords: Cactaceae, Echinopsis, floral syndrome, passerine, pollination. Les fleurs de cactus ont traditionnellement ete considerees comme specialisees envers certaines guildes de pollinisateurs, mais les etudes de pollinisation revelent que la plupart des especes sont en fait generalistes. Cela suggere que les traits floraux ne sont pas toujours predicteurs des visiteurs animaux qui pollinisent les fleurs de cactus. Les auteurs ont etudie ici la pollinisation d'Echinopsis leucantha (Gillies ex Salm-Dyck) Walp., un cactus endemique de l'Argentine, dont les traits floraux pourraient suggerer qu'il est pollinise par des papillons nocturnes. La duree de vie et la disponibilite des fleurs a travers toute la periode de reproduction ont ete evaluees. Des experiences sur le terrain ont ete realisees afin d'etudier le systeme reproducteur et l'identite et l'efficacite des visiteurs floraux. Les fleurs d'E. leucantha avaient une periode d'anthese nocturne qui s'etendait durant la matinee suivante. L'espece etait auto-incompatible. Les visiteurs floraux comprenaient les papillons nocturnes, les abeilles et les passereaux. Cependant, les visiteurs diurnes etaient des pollinisateurs plus efficaces que les visiteurs nocturnes. Les fleurs d'E. leucantha etaient specialisees phenotypiquement (sphingophilie); cependant, le systeme pollinisateur etait fonctionnellement et ecologiquement generaliste. Les resultats confirment que les systemes de pollinisation generalistes sont repandus chez les especes du genre Echinopsis possedant des fleurs nocturnes, pour lesquelles les pollinisateurs diurnes semblent jouer un role cle dans la production de fruits et de graines. Leur etude est la premiere a rapporter une pollinisation par des passereaux chez des Cactaceae du continent sudamericain. [Traduit par la Redaction] Mots-cles : Cactaceae, Echinopsis, syndrome floral, passereau, pollinisation., Introduction Most angiosperms have been found to have generalist pollination systems, and specialization is now believed to be less common than once supposed (Waser et al. 1996; Ollerton et al. [...]

Abstract Climate change can disrupt mutualisms by causing temporal or spatial mismatch between interacting species. However, the effects of climate change forecasts on biotic interactions remain poorly studied. In cactus species, pollination constitutes a fundamental process in the production of fruits and seeds. Thus, we aimed to analyse the impact of future climate change on the geographical distributions of 11 cactus species from the southern Central Andes and their spatial match with their pollinators. We used species distribution modelling to forecast the geographic range shifts of these cactus species and their pollinators under two future scenarios (RCP 4.5 and RCP 8.5) for the years 2050 and 2070. We predicted geographic range contractions under future scenarios that reached almost 80% for some cactus species. Our results indicate that the geographical distributions of cacti would be constrained by the presence of the pollinator species on which they depend in the present; however, climate change would not cause spatial mismatch between cacti and their animal pollinators in the future. For most cactus species, we predicted an increase in the spatial match with their mutualists under future scenarios. This is the first study that estimates the geographic range of cacti using both abiotic and biotic factors. Given the importance that positive interactions have on the life cycle of many plant species, our approach could be used to better understand the potential effects of climate change, particularly on species that are of special interest for conservation actions. Highlights • We estimate the geographic range of cacti using both abiotic and biotic factors. • The current range of cacti would be constrained by the presence of their pollinators. • Severe geographic range contractions were predicted under future climate scenarios. • Climate change would not cause spatial mismatch between cacti and their pollinators in the future. [ABSTRACT FROM AUTHOR]

Floral nectaries are essential for plant reproduction but little is known about the relationship between these secretory structures and pollination system in cacti. To test phenotypic patterns in nectaries associated with pollination syndromes and/or with its pollinators, we selected from evolutionarily related genera Cleistocactus, Denmoza, and Echinopsis, a set of species with bird-pollinated flowers and floral traits that may fit with ornithophily or with sphingophily, and other set of sphingophilous species with moths as effective pollinator. Observations were made under light microscope and scanning and transmission electron microscopes. Nectaries are located at the base of the filaments welded to the tube, forming a chamber. The nectary consists of the epidermis with distinctive features in each genus, a secretory parenchyma which may be vascularized and a non-secretory vascularized parenchyma. Anatomical variants observed in nectaries of different species are not consistent with the floral pollination syndromes neither with groups of pollinators. The basic structure of the nectar chamber is relatively conserved, a fact that may be explained by phylogenetic conservatism among the genera investigated. Our results revalue the role of anatomical traits for the systematics of Cactaceae.

Background and Aims: Large clades of angiosperms are often characterized by diverse interactions with pollinators, but how these pollination systems are structured phylogenetically and biogeographically is still uncertain for most families. Apocynaceae is a clade of >5300 species with a worldwide distribution. A database representing >10 % of species in the family was used to explore the diversity of pollinators and evolutionary shifts in pollination systems across major clades and regions., Methods: The database was compiled from published and unpublished reports. Plants were categorized into broad pollination systems and then subdivided to include bimodal systems. These were mapped against the five major divisions of the family, and against the smaller clades. Finally, pollination systems were mapped onto a phylogenetic reconstruction that included those species for which sequence data are available, and transition rates between pollination systems were calculated., Key Results: Most Apocynaceae are insect pollinated with few records of bird pollination. Almost three-quarters of species are pollinated by a single higher taxon (e.g. flies or moths); 7 % have bimodal pollination systems, whilst the remaining approx. 20 % are insect generalists. The less phenotypically specialized flowers of the Rauvolfioids are pollinated by a more restricted set of pollinators than are more complex flowers within the Apocynoids + Periplocoideae + Secamonoideae + Asclepiadoideae (APSA) clade. Certain combinations of bimodal pollination systems are more common than others. Some pollination systems are missing from particular regions, whilst others are over-represented., Conclusions: Within Apocynaceae, interactions with pollinators are highly structured both phylogenetically and biogeographically. Variation in transition rates between pollination systems suggest constraints on their evolution, whereas regional differences point to environmental effects such as filtering of certain pollinators from habitats. This is the most extensive analysis of its type so far attempted and gives important insights into the diversity and evolution of pollination systems in large clades.