Sissi Lozada-Gobilard

Urban environments can generate substantial spatial and temporal variation in pollinator assemblages, floral traits, and resource availability, yet how plant reproduction is maintained under such heterogeneous conditions remains poorly understood, particularly in tropical cities. In Nicotiana glauca (Solanaceae), floral traits and pollinator assemblages vary among natural populations, but information from urban environments is lacking. We investigated pollination dynamics and reproductive success of N. glauca across a heterogeneous urban landscape in the high tropical Andes by integrating flower visitation, floral trait variation, functional morphology, and reproductive output. Flower visitation varied strongly among visitor groups, times of day, and urban regions. Hummingbirds were the only legitimate pollinators, whereas bees acted exclusively as nectar robbers. We report Colibri coruscans and Elliotomyia chionogaster as pollinators of N. glauca for the first time. Despite pronounced spatial and temporal variation in floral traits and visitor assemblages, including complete spatial turnover between hummingbird species, fruit set remained consistently high (> 90%) across all urban regions. No fruits were produced in pollinator‐excluded flowers, suggesting dependence on animal‐mediated pollination. Although flower tube length generally exceeded hummingbird bill length, both species appeared functionally compatible with the flowers and carried pollen on their beaks during visitation. Our results show that N. glauca maintains high reproductive success across heterogeneous urban environments, through hummingbird‐mediated pollination, highlighting the resilience of some plant–pollinator interactions in rapidly urbanizing tropical landscapes.

Pollination is a key ecological process sustaining biodiversity and food security, yet global patterns of plant–pollinator specialization remain unresolved. Using a global dataset of quantitative plant–pollinator networks (>3,400 networks, >110,000 interactions), we show that specialization is latitudinally structured, but not as a single directional pattern. We find no consistent monotonic increase or decrease in specialization towards the Equator. Instead, network-level and pollinator specialization peak at low northern latitudes near the tropical–subtropical boundary, whereas plant specialization is hemispherically asymmetric. Climate is most often the best-supported predictor of specialization compared with latitude, biodiversity and environmental productivity. Network-level specialization declines with increasing mean annual temperature, with strong group-specific differences. Precipitation exerts nonlinear effects: plant specialization peaks at intermediate precipitation but is lower at the wettest sites, whereas pollinator specialization is lower at intermediate precipitation, although often in interaction with temperature. Pollinator groups diverge strongly, especially in contrasting precipitation-related patterns between birds and insects. These findings show that global plant–pollinator specialization is structured by latitude and climate in complex and taxon-specific ways, with implications for uneven responses of pollination networks to future climatic change.

Premise: Flower color, a key trait influencing plant–pollinator interactions, may be influenced by abiotic factors such as soil. We investigated association between pollinators, soil characteristics, and flower color variations in Digitalis purpurea across native populations in Sweden and introduced populations in Bolivia. Methods: We measured floral traits, reflectance of petals and nectar‐guide spots, plant size, pollinator visitation, fruit set, seed production, germination, and soil characteristics. Results: Individuals were categorized into violet, pink, and white morphs, which were confirmed by spectral measurements and bee vision modelling. Reflectance of inner nectar‐guide spots overlapped across morphs, potentially limiting pollinator discrimination. Bumblebees were the main pollinators in all populations. Although visitation varied among morphs, pollinator visits to different color morphs were population specific. In Bolivia, violet flowers were predominant (70–87%), with pink (13–17%) and white (0–13%) at lower frequencies. In Sweden, morph frequencies were more even (violet 20–43%, pink 38–69%, white 11–30%). Morph frequency was not associated with soil composition, despite differences between regions. Reproductive fitness varied across populations but not consistently among morphs: The largest Swedish population had the highest fruit set but the lowest seed set, while germination was lower in Bolivia. Phosphorus was lower in soil beneath violet individuals; other soil variables, plant size, and floral traits did not differ among color morphs. Conclusions: Floral color variation in D. purpurea was not significantly related to pollinator visitation or soil conditions at the spatial scale examined, suggesting maintenance by local environmental conditions, neutrality, or historical and demographic processes rather than selection.

The genus Lupinus (Fabaceae) represents an exceptional model system for studying evolutionary processes mediated by pollinators and environmental factors. This review synthesizes evidence on phenotypic variability of floral traits, trait selection by biotic and abiotic factors, and the eco-evolutionary implications of these interactions. Pollinators shape floral traits through specialized selection that optimizes pollination efficiency while maintaining plasticity toward autogamy under pollinator scarcity. At the same time, abiotic pressures drive adaptations to climate and elevation, which Lupinus achieves through phenotypic plasticity, such as adjusting flowering time, and through mutualisms with soil microbes that reduce abiotic stress. Ecological implications reveal contrasting dynamics, where native species sustain specialized pollination networks, while invasive species such as L. polyphyllus Lindl. disrupt these interactions through competitive exclusion. Thus, these two factors collectively drive Lupinus phenotypic diversity through specialized adaptations and plasticity. Finally, we emphasize the need for integrated studies combining genomics and ecological modeling to decipher the adaptive mechanisms of this genus.

Speciation is a dynamic process shaped by the interaction of gene flow, geographic isolation, and ecological divergence. The Oncocyclus irises of the Southern Levant represent a young radiation of narrowly endemic species considered to be in the course of speciation. In this study, we used RAD-sequencing and single nucleotide polymorphism analysis across nine described species to investigate patterns of genomic divergence, gene flow, and local adaptation. Phylogenomic analyses revealed a mix of well-supported clades for some species, previously defined by their morphology and distribution, and non-monophyletic lineages, with several species exhibiting shallow divergence and shared genetic ancestry. We found evidence for gene flow and historical introgression between Iris petrana , I. atrofusca and I. mariae , while other cases of non-monophyly appear driven by incomplete lineage sorting. Both geographic distance (IBD) and environmental factors (IBE), mainly altitude, temperature, and aridity, were significantly associated with genetic structure, suggesting that local adaptation contributed to divergence following range expansion. Based on our findings we propose that the divergence of the Oncocyclus iris species in the Southern Levant supports a stepping-stone dispersion model, in which north-to-south dispersal was followed by local adaptation, and introgression in secondary contact zones. Overall, these findings highlight the complexity of speciation and the need for integrative approaches to study the interplay between historical divergence, contemporary gene flow, and environmental differentiation in shaping genomic patterns.

Pollination is a key ecological process sustaining biodiversity and food security, yet global patterns of plant–pollinator specialisation have remained unresolved. Using the largest global dataset of quantitative networks (>3,400 networks, >110,000 interactions), we show that the latitudinal specialisation gradient (LSG) exists, but it is non-linear, hemispherically asymmetric, and strongly taxon-dependent. Network-level and pollinator specialisation were lowest in the tropics and peaked at northern mid-latitudes, whereas plants tended to become more specialised toward higher latitudes. Climate consistently outperformed latitude, species richness, and environmental productivity as a predictor of these patterns. Specialisation declined with increasing temperature, rose with moderate rainfall before declining at the wettest sites, and increased with temperature seasonality, but plants and pollinators responded differently to these drivers. Functional groups diverged strongly: ectothermic insects were most specialised in cooler, seasonal climates, while birds showed weaker links to latitude but reduced specialisation in wetter regions. These findings demonstrate that climate, rather than latitude or species richness, structures global variation in specialisation. Because warmer and less seasonal climates promote generalisation, climate change is likely to disrupt the most specialised pollination systems, unevenly across taxa and regions, with important consequences for biodiversity and ecosystem stability.

Stingless bees (Meliponini) are important pollinators in tropical ecosystems and very abundant in the Bolivian Yungas region; yet little is known about their foraging behavior and floral preferences. In this study, we combined melissopalynology, pollen analysis from honey, with plant‐pollinator interactions network to investigate foraging behavior and niche overlap of three rescued stingless bee species (Tetragonisca angustula, Nannotrigona testaceicornis, and Paratrigona opaca) in Bolivia's tropical Andes. Our results suggest different floral foraging patterns between bee species and hives. Tetragonisca angustula consistently preferred Melastomataceae across its hives, while N. testaceicornis and P. opaca showed more varied foraging patterns, with P. opaca favoring Oxalidaceae. Our results also indicate that these foraging differences are influenced by the types of flowers available, indicating that species interact with non‐native species if they are in the area. Therefore, our results emphasize the need to preserve a high diversity of floral resources for bees, as well as maintaining diversity within and among stingless bee species to support plant–pollinator interactions in tropical ecosystems. The low level of niche overlap might be a way to avoid competition, with distinct foraging patterns both inter‐ (between species) and intra‐specific (between hives). We encourage the use of native stingless bee species for honey production as a tool to promote conservation and reproduction of non‐native and native plant species of the region.

Large flowers are typically more conspicuous to pollinators and are associated with more nutritional rewards than small flowers. Flower size can also determine flower temperature, which can be a reward for flower-visiting insects. Nectarless Royal irises offer overnight shelter and morning warmth to male Eucera bee pollinators. A dark spot on their lower tepals (black patch) may act as a visual cue and contribute to flower heating. Here, we examined the association of floral display (i.e. flower size and black patch size) with flower temperature and female fitness (i.e. seed set) in Royal irises populations across an aridity gradient. First, we tested pollinator preference using artificial flowers of varying sizes. Next, we assessed associations between flower and black patch size, flower warming rate and female fitness. Finally, we manipulated flowers in the field to determine if the black patch influences heating. Pollinators preferred larger artificial flowers for overnight shelter. However, selection for larger flowers was found only in the population with the smallest flowers. No association was found between flower/black patch size and floral heating in natural populations, and the black patch did not affect flower heating. Flowers reached the temperature threshold for bees to start flying (18 °C) 10–35 min faster than ambient air. We conclude that the large flower size in the Royal irises serves as a visual signal, advertising for night shelter and flowers—independently of the size—heat up faster in the morning than ambient air. Flowers thus, potentially offer a ‘head start’ to the flower-dwelling bees, allowing them to warm up more quickly than in outside conditions.

Two new endemic species from Bolivia, Gomphrena vallegrandensis T. Ortuño & S. Lozada-Gobilard and Gomphrena palmariensis T. Ortuño, J. Gutiérrez. & Montesinos, are described and illustrated. The former only occurs in the native open natural grassland close to the Tucuman forest (Prov. Vallegrande), and the latter is restricted to the areas with rock outcrops in the subpuna close to the inter-Andean dry forest in the El Palmar Integrated Management Natural Area. A full description of these two new species, notes on their distribution, and a key for their identification are provided.

Las flores han desarrollado diversas señales para atraer a los polinizadores, como el color y la forma. Además, algunas especies han desarrollado morfotipos que difieren en la posición de sus órganos sexuales (heterostilia). El objetivo de este estudio fue determinar si la transferencia de polen estará restringida por la especie, entre dos especies con flores morfológicamente similares, Turnera krapovickasii (Passifloraceae) y Pavonia sidifolia (Malvaceae), y si dentro de una misma especie, T. krapovickasii, la transferencia de polen está facilitada por la heterostilia. Para observar la transferencia de polen se utilizaron polvos fluorescentes como análogos. Se realizó una prueba de chi cuadrado para evaluar si la transferencia de análogos de polen fue mayor o menor de lo esperado al azar. Nuestros resultados muestran que la transferencia de análogos estuvo restringida por la especie siendo menor de lo esperado al azar. Por otro lado, la transferencia no fue facilitada por la presencia de heterostilia, la transferencia intra morfotipo fue mayor de lo esperado al azar. Los resultados reflejan la tendencia de los polinizadores a visitar las flores de un mismo individuo antes de moverse a otro, por lo menos durante la primera hora de exposición de los análogos. Se recomienda evaluar la transferencia de polen incrementando el tiempo de exposición de los análogos de polen, evaluar el efecto de la distancia entre los parches de T. krapovickasii y P. sidifolia y además investigar más sobre los polinizadores que comparten.