Quantitative assessments of endemism, evolutionary distinctiveness and extinction threat underpin global conservation prioritization for well-studied taxa, such as birds, mammals, and amphibians. ...However, such information is unavailable for most of the world's taxa. This is the case for the Orchidaceae, a hyperdiverse and cosmopolitan family with incomplete phylogenetic and threat information. To define conservation priorities, we present a framework based on phylogenetic and taxonomic measures of distinctiveness and rarity based on the number of regions and the area of occupancy. For 25,434 orchid species with distribution data (89.3% of the Orchidaceae), we identify the Neotropics as hotspots for richness, New Guinea as a hotspot for evolutionary distinctiveness, and several islands that contain many rare and distinct species. Orchids have a similar proportion of monotypic genera as other Angiosperms, however, more taxonomically distinct orchid species are found in a single region. We identify 278 species in need of immediate conservation actions and find that more than 70% of these do not currently have an IUCN conservation assessment and are not protected in ex-situ collections at Botanical Gardens. Our study highlights locations and orchid species in urgent need of conservation and demonstrates a framework that can be applied to other data-deficient taxa.
Land management change towards intensive grazing has been shown to alter plant and pollinator communities and the structure of plant-pollinator interactions in different ways across the world. ...Land-use intensification in Eastern Europe is shifting highly diverse, traditionally managed hay meadows towards intensive pastures, but few studies have examined how this influences plant-pollinator networks. We hypothesized that the effects of intensive grazing on networks will depend on how plant communities and their floral traits change.
We investigated plant and pollinator diversity and composition and the structure of plant-pollinator interactions near Sibiu, Romania at sites that were traditionally managed as hay meadows or intensive pastures. We quantified the identity and abundance of flowering plants, and used transect walks to observe pollinator genera interacting with flowering plant species. We evaluated the effects of management on diversity, composition and several indices of network structure.
Pollinator but not plant diversity declined in pastures and both plant and pollinator taxonomic composition shifted. Functional diversity and composition remained unchanged, with rather specialized flowers having been found to dominate in both hay meadows and pastures.
was found to be the most abundant pollinator. Its foraging preferences played a crucial role in shaping plant-pollinator network structure.
thus preferred the highly abundant
in hay meadows, leading to hay meadows networks with lower Shannon diversity and interaction evenness. In pastures, however, it preferred less abundant and more generalized flower resources. With pollinators being overall less abundant and more generalized in pastures, we found that niche overlap between plants was higher.
With both hay meadows and pastures being dominated by plant species with similar floral traits, shifts in pollinator preferences seem to have driven the observed changes in plant-pollinator interaction networks. We thus conclude that the effects of grazing on pollinators and their interactions are likely to depend on the traits of plant species present in different management types as well as on the effects of grazing on plant community composition. We thereby highlight the need for better understanding how floral abundance shapes pollinator visitation rates and how floral traits may influence this relationship.
Complex socio-economic, political and demographic factors have driven the increased conversion of Europe's semi-natural grasslands to intensive pastures. This trend is particularly strong in some of ...the most biodiverse regions of the continent, such as Central and Eastern Europe. Intensive grazing is known to decrease species diversity and alter the composition of plant and insect communities. Comparatively little is known, however, about how intensive grazing influences plant functional traits related to pollination and the structure of plant-pollinator interactions. In traditional hay meadows and intensive pastures in Central Europe, we contrasted the taxonomic and functional group diversity and composition, the structure of plant-pollinator interactions and the roles of individual species in networks. We found mostly lower taxonomic and functional diversity of plants and insects in intensive pastures, as well as strong compositional differences among the two grassland management types. Intensive pastures were dominated by a single plant with a specialized flower structure that is only accessible to a few pollinator groups. As a result, intensive pastures have lower diversity and specificity of interactions, higher amount of resource overlap, more uniform interaction strength and lower network modularity. These findings stand in contrast to studies in which plants with more generalized flower traits dominated pastures. Our results thus highlight the importance of the functional traits of dominant species in mediating the consequences of intensive pasture management on plant-pollinator networks. These findings could further contribute to strategies aimed at mitigating the impact of intensive grazing on plant and pollinator communities.
The Omusati region belongs to historic Ovamboland, an area of northern Namibia populated by tribes of the Ovambo group. Four very large African baobabs of Omusati played an important role in historic ...events of the area, such as the tribal wars and the Namibian War of Independence. The four historic baobabs are the Ombalantu baobab (8 stems; circumference 24.50 m), Okahao baobab (4+ stems; around 25 m), Amadhila baobab (12 stems; 25.35 m) and Sir Howard baobab (9 stems; 31.60 m). Two historic baobabs collapsed totally or partially. The stems of the Amadhila baobab toppled and died in 2021, while 3 stems of the Okahao baobab collapsed a long time ago, but are still alive. Our research aimed to determine the architecture and age of these baobabs. Three baobabs (Ombalantu, Amadhila, Sir Howard) exhibit a closed ring-shaped structure, with a false cavity inside. One baobab (Okahao) had an open ring-shaped structure, before its collapse. Several wood cores were extracted from the baobabs and investigated by radiocarbon dating. The dating results indicate ages of 770 ± 50 years for the Ombalantu baobab, 650 ± 50 years for the Okahao baobab, 1100 ± 50 years for the Amadhila baobab and 750 ± 50 years for the Sir Howard baobab.
Societal Impact Statement
Pollen relates to many aspects of human and environmental health, which protection and improvement are endorsed by the United Nations Sustainable Development Goals. By ...highlighting these connections in the frame of current challenges in monitoring and research, we discuss the need of more integrative and multidisciplinary pollen research related to societal needs, improving health of humans and our ecosystems for a sustainable future.
Summary
Pollen is at once intimately part of the reproductive cycle of seed plants and simultaneously highly relevant for the environment (pollinators, vector for nutrients, or organisms), people (food safety and health), and climate (cloud condensation nuclei and climate reconstruction). We provide an interdisciplinary perspective on the many and connected roles of pollen to foster a better integration of the currently disparate fields of pollen research, which would benefit from the sharing of general knowledge, technical advancements, or data processing solutions. We propose a more interdisciplinary and holistic research approach that encompasses total environmental pollen diversity (ePD) (wind and animal and occasionally water distributed pollen) at multiple levels of diversity (genotypic, phenotypic, physiological, chemical, and functional) across space and time. This interdisciplinary approach holds the potential to contribute to pressing human issues, including addressing United Nations Sustainable Development Goals, fostering social and political awareness of these tiny yet important and fascinating particles.
Pollen relates to many aspects of human and environmental health, which protection and improvement are endorsed by the United Nations Sustainable Development Goals. By highlighting these connections in the frame of current challenges in monitoring and research, we discuss the need of more integrative and multidisciplinary pollen research related to societal needs, improving health of humans and our ecosystems for a sustainable future.
Despite increased focus on elucidating the various reproductive strategies employed by orchids, we still have only a rather limited understanding of deceptive pollination systems that are not bee- or ...wasp-mediated. In Europe, the orchid
Neotinea ustulata
has been known to consist of two phenologically divergent varieties, neither of which provide rewards to its pollinators. However, detailed studies of their reproductive biology have been lacking. Our study aimed to characterize and understand the floral traits (i.e., morphology, color, and scent chemistry) and reproductive biology of
N. ustulata
. We found that the two varieties differ in all their floral traits; furthermore, while
Neotinea ustulata
var.
ustulata
appears to be pollinated by both bees (e.g.,
Anthophora
,
Bombus
) and flies (e.g.,
Dilophus, Tachina
), var.
aestivalis
is pollinated almost entirely by flies (i.e.,
Nowickia, Tachina
). Tachinids were also found to be much more effective than bees in removing pollinaria, and we show experimentally that they use the characteristic dark inflorescence top as a cue for approaching inflorescences. Our results thus suggest that while both
N. ustulata
varieties rely on tachinids for pollination, they differ in their degree of specialization. Further studies are, however, needed to fully understand the reproductive strategy of
N. ustulata
varieties.
Sexually deceptive orchids mimic signals emitted by female insects in order to attract mate-searching males. Specific attraction of the targeted pollinator is achieved by sex pheromone mimicry, which ...constitutes the major attraction channel. In close vicinity of the flower, visual signals may enhance attraction, as was shown recently in the sexually deceptive orchid
Ophrys heldreichii
. Here, we conducted an in situ manipulation experiment in two populations of
O. heldreichii
on Crete to investigate whether the presence/absence of the conspicuous pink perianth affects reproductive success in two natural orchid populations. We estimated reproductive success of three treatment groups (with intact, removed and artificial perianth) throughout the flowering period as pollinaria removal (male reproductive success) and massulae deposition (female reproductive success). Reproductive success was significantly increased by the presence of a strong visual signal—the conspicuous perianth—in one study population, however, not in the second, most likely due to the low pollinator abundance in the latter population. This study provides further evidence that the coloured perianth in
O. heldreichii
is adaptive and thus adds to the olfactory signal to maximise pollinator attraction and reproductive success.
Summary
Pollen identification and quantification are crucial but challenging tasks in addressing a variety of evolutionary and ecological questions (pollination, paleobotany), but also for other ...fields of research (e.g. allergology, honey analysis or forensics). Researchers are exploring alternative methods to automate these tasks but, for several reasons, manual microscopy is still the gold standard.
In this study, we present a new method for pollen analysis using multispectral imaging flow cytometry in combination with deep learning. We demonstrate that our method allows fast measurement while delivering high accuracy pollen identification.
A dataset of 426 876 images depicting pollen from 35 plant species was used to train a convolutional neural network classifier. We found the best‐performing classifier to yield a species‐averaged accuracy of 96%. Even species that are difficult to differentiate using microscopy could be clearly separated.
Our approach also allows a detailed determination of morphological pollen traits, such as size, symmetry or structure. Our phylogenetic analyses suggest phylogenetic conservatism in some of these traits. Given a comprehensive pollen reference database, we provide a powerful tool to be used in any pollen study with a need for rapid and accurate species identification, pollen grain quantification and trait extraction of recent pollen.
Ophrys
flowers mimic sex pheromones of attractive females of their pollinators and attract males, which attempt to copulate with the flower and thereby pollinate it. Virgin females and orchid flowers ...are known to use the same chemical compounds in order to attract males. The composition of the sex pheromone and its floral analogue, however, vary between pollinator genera. Wasp-pollinated
Ophrys
species attract their pollinators by using polar hydroxy acids, whereas
Andrena
-pollinated species use a mixture of non-polar hydrocarbons. The phylogeny of
Ophrys
shows that its evolution was marked by episodes of rapid diversification coinciding with shifts to different pollinator groups: from wasps to
Eucera
and consequently to
Andrena
and other bees. To gain further insights, we studied pollinator attraction in
O. leochroma
in the context of intra- and inter-generic pollinator shifts, radiation, and diversification in the genus
Ophrys
. Our model species,
O. leochroma
, is pollinated by
Eucera kullenbergi
males and lies in the phylogeny between the wasp and
Andrena
-pollinated species; therefore, it is a remarkable point to understand pollinator shifts. We collected surface extracts of attractive
E. kullenbergi
females and labellum extracts of
O. leochroma
and analyzed them by using gas chromatography with electroantennographic detection (GC-EAD) and gas chromatography coupled with mass spectrometry (GC-MS). We also performed field bioassays. Our results show that
O. leochroma
mimics the sex pheromone of its pollinator’s female by using aldehydes, alcohols, fatty acids, and non-polar compounds (hydrocarbons). Therefore, in terms of the chemistry of pollinator attraction,
Eucera
-pollinated
Ophrys
species might represent an intermediate stage between wasp- and
Andrena
-pollinated orchid species.
Mutualistic interactions between plants and animal pollinators are increasingly under threat through anthropogenic change, and it is critical to understand how temporal changes affect the structure ...and function of these ecologically important interactions.
Because the responses of plant–pollinator interactions to anthropogenic change may take place over decades, historical collections that store information across long time horizons contribute uniquely to our understanding.
In this article, we highlight several key questions related to long‐term changes in the structure and function of plant–pollinator interactions. We articulate how research could proceed rapidly via new techniques, greater integration of resources in museum collections along with coincident use of a single data source.
We acknowledge the challenges that come with using historical collections and discuss how to minimize them. We provide suggestions that will allow for full utilization of museum resources for addressing a variety of issues regarding plant–pollinator interactions.
This perspective paper aims to stimulate new integrative research aimed at understanding temporal patterns in plant–pollinator interactions.
Read the free Plain Language Summary for this article on the Journal blog.
Read the free Plain Language Summary for this article on the Journal blog.
PDF
