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Pollination and Floral Ecology is the most comprehensive single-volume reference to all aspects of pollination biology--and the first fully up-to-date resource of its kind to appear in decades. This beautifully illustrated book describes how flowers use colors, shapes, and scents to advertise themselves; how they offer pollen and nectar as rewards; and how they share complex interactions with beetles, birds, bats, bees, and other creatures. The ecology of these interactions is covered in depth, including the timing and patterning of flowering, competition among flowering plants to attract certain visitors and deter others, and the many ways plants and animals can cheat each other.

Abstract 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 Methods The database was compiled from published and unpublished reports.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.

Pollinator nutritional ecology provides insights into plant–pollinator interactions, coevolution, and the restoration of declining pollinator populations. Bees obtain their protein and lipid nutrient intake from pollen, which is essential for larval growth and development as well as adult health and reproduction. Our previous research revealed that pollen protein to lipid ratios (P:L) shape bumble bee foraging preferences among pollen host-plant species, and these preferred ratios link to bumble bee colony health and fitness. Yet, we are still in the early stages of integrating data on P:L ratios across plant and bee species. Here, using a standard laboratory protocol, we present over 80 plant species’ protein and lipid concentrations and P:L values, and we evaluate the P:L ratios of pollen collected by three bee species. We discuss the general phylogenetic, phenotypic, behavioral, and ecological trends observed in these P:L ratios that may drive plant–pollinator interactions; we also present future research questions to further strengthen the field of pollination nutritional ecology. This dataset provides a foundation for researchers studying the nutritional drivers of plant–pollinator interactions as well as for stakeholders developing planting schemes to best support pollinators.

Pollination of deceptive orchids has enabled scientists to understand how these species avoid inbreeding depression by reducing the number of pollinator visits per inflorescence. In rewarding species, which receive a higher rate of visits per plant, geitonogamy is usually higher and therefore the risk of inbreeding increases. In this study, we assess the breeding system of the rewarding orchid A. coriophora, and the spatio-temporal changes in its fitness as well as variation in nectar content after pollination. We found that the species partially selects allogamous pollen if pollinia from the same stalk and other plants arrive to the stigma. Furthermore, when self-pollination occurs, despite successful fructification, seed viability is significantly lower than that of cross-pollinated plants. A. coriophora exhibits spatio-temporal variation in fitness that does not correlate with any plant feature. Moreover, nectar volume is reduced after pollination, but the sugar concentration is maintained. This study emphasizes how essential the pre-zygotic and post-zygotic reproductive barriers are for rewarding orchids to avoid inbreeding depression.

Summary Floral colour mediates plant–pollinator interactions by often signalling floral resources. In this sense, hummingbird‐pollinated flowers are frequently red‐coloured, and there are two tentative hypotheses to explain this pattern: 1. hummingbirds are attracted to red due its easier detection and 2. bees are sensorially excluded from red flowers. The second hypothesis is based on bees’ red colour blindness, which lead them to be less frequent and less important than hummingbirds as pollinators of red‐reflecting flowers. Here, we untangled the role of different flower traits mediating plant–pollinator interactions and empirically tested the above hypotheses. We chose Costus arabicus due to its synchronopatric white‐ and pink‐flowered individuals and its bee and hummingbird pollination system. Although pink flowers are not totally achromatic as pure red ones, they show an achromaticity degree that could drive bee exclusion. Specifically, we tested whether differences on red reflectance work attracting hummingbirds or excluding bees and the consequent implications for the plant's reproduction. Flower colour morphs of C. arabicus do differ neither in morphology nor in nectar sugar content. Moreover, white and pink flowers can be discriminated by the bees’ and hummingbirds’ colour vision system. Both groups are able to discriminate the red colour variation morph on the flower petals, the white flowers being more easily detected by bees and the pink flowers by hummingbirds. Bees preferentially visited the white flowers, whereas hummingbirds visited both colours at the same rate – both patterns corroborating the second hypothesis. Pollen loads deposited on stigmas did not differ between flower colour morphs, indicating that bees and hummingbirds play a similar role in the overall pollen deposition. However, bees are more likely to self‐pollinate than hummingbirds. Self‐pollination limits C. arabicus reproduction, and red‐reflecting flowers may be better pollinated by discouraging bee visitation. Therefore, the intraspecific colour variation is driving flowers to show colour‐related different levels of generalization. Our results support the ‘bee avoidance’ rather than the ‘hummingbird preference’ hypothesis. Sensory exclusion of bees seems to be the pressure for red‐reflecting flowers evolution, driving specialization in hummingbird‐pollinated flowers due to the costs of bee pollination on plant reproduction. Lay Summary

Buzz pollination is a behavior in which bees vibrate anthers to cause the release of pollen. It is most commonly observed on flowers with poricidal anthers that release pollen through small apical pores, but has also been documented on non-poricidal flowers that freely release pollen. While the vibrational characteristics of floral buzzes on poricidal species have been well described, less is known about vibrations on non-poricidal species and how their characteristics compare. In this study, we recorded floral and flight buzzes from bumblebees visiting aspen bluebells (Mertensia arizonica), a non-poricidal species. Floral buzz frequencies were higher than flight buzz frequencies and were positively correlated with temperature. Frequencies were similar to those of bees visiting poricidal flowers, suggesting that bees don't alter the spectral characteristics of floral buzzes based on the morphology of the flowers they are visiting. La polinización del zumbo es una característica observada en abejas en que ellos vibran las anteras para provocar la suelta del polvo. Se observa mayormente en flores con anteras poricidas que sueltan polvo a través de pequeños poros apicales, pero también se ha documentado en flores no poricidas que sueltan polvo libremente. Aunque las propiedades vibracionales de los zumbidos florales en especies poricidas están bien documentadas, se sabe menos sobre las vibraciones en especies no poricidas y como sus características se comparan. En este estudio, recordamos zumbidos de florales y de vuelo de abejorros que visitaban flores de campanillas (Mertensia arizonica), una especie no poricida. Las frecuencias de los zumbidos florales fueron más altas que las de los zumbidos de vuelo y estuvieron positivamente correlacionadas con la temperatura. Las frecuencias fueron similares a las de abejas que visitan flores poricidas, lo que sugiere que las abejas no alteran las características espectrales de los zumbidos florales en función de la morfología de las flores que visitan.

The Andean mountains of South America are the most species-rich biodiversity hotspot worldwide with c. 15% of the world’s plant species, in only 1% of the world’s land surface. Orchids are a key element of the Andean flora, and one of the most prominent components of the Neotropical epiphyte diversity, yet very little is known about their origin and diversification. We address this knowledge gap by inferring the biogeographical history and diversification dynamics of the two largest Neotropical orchid groups (Cymbidieae and Pleurothallidinae), using two unparalleled, densely sampled orchid phylogenies (including more than 400 newly generated DNA sequences), comparative phylogenetic methods, geological and biological datasets. We find that the majority of Andean orchid lineages only originated in the last 20–15 million yr. Andean lineages are derived from lowland Amazonian ancestors, with additional contributions from Central America and the Antilles. Species diversification is correlated with Andean orogeny, and multiple migrations and recolonizations across the Andes indicate that mountains do not constrain orchid dispersal over long timescales. Our study sheds new light on the timing and geography of a major Neotropical diversification, and suggests that mountain uplift promotes species diversification across all elevational zones.

The Platanthera Rich. (Orchidoideae) comprise a speciose genus of orchids primarily in the northern hemisphere, with up to 200 known species worldwide. Individual species are known to self‐pollinate, but many rely on insect pollinators with characteristics such as floral color, timing of floral odor emissions, nectar rewards, and spur length associated with particular pollination syndromes. As with many orchids, some orchid–pollinator associations are likely highly co‐evolved, but we also know that some Platanthera spp. are the result of hybridization events, which implies a lack of pollinator fidelity in some cases. Some Platanthera spp. occur in large numbers which, coupled with the numerous Platanthera–pollinator systems, make them accessible as study species and useful for co‐evolutionary studies. Due to the likely effects of climate change and ongoing development on Platanthera spp. habitats, these orchids and their associated pollinators should be a focus of conservation attention and management. However, while there is a fairly substantial literature coverage of Platanthera–pollinator occurrence and interactions, there are still wide gaps in our understanding of the species involved in these systems. In this systematic review, we outline what is current knowledge and provide guidance on further research that will increase our understanding of orchid–insect co‐evolutionary relationships. Our review covers 157 orchid species and about 233 pollinator species interacting with 30 Platanthera spp. We provide analyses on aspects of these interactions such as flower morphology, known insect partners of Platanthera species, insect‐Platanthera specificity, pollination visitor timing (diurnal vs. nocturnal), floral rewards, and insect behavior affecting pollination outcomes (e.g., pollinia placement). A substantial number of Platanthera spp. and at least a few of their known pollinators are of official (IUCN) conservation concern – and many of their pollinators remain unassessed or even currently unknown – which adds to the urgency of further research on these co‐evolved relationships. This review of Platanthera pollination ecology shows that there are a number of orchid species in the group without pollinator information. Considerable knowledge gaps were identified even for those species where pollinator information has been reported, and these gaps impact our ability to appropriately manage orchid and pollinator populations, which may negatively effect conservation efforts. We provide a number of recommendations that can be applied broadly to a number of plant groups to further our understanding of pollination ecology.