Pollinator‐mediated processes (biotic filtering, facilitation or competition) are often inferred by patterns of plant reproductive trait diversity (clustering or evenness of reproductive traits ...within the community). However, one single pattern can be generated by distinct processes, making difficult to predict the main process of community assembly. Incorporating fitness estimates should improve the link between pattern and process.
We investigated patterns of flowering phenology and reproductive traits (floral colour, floral size and anther height) along the season of a pollinator‐depauperated and generalized community. We used data on fitness (pollen receipt and number of pollen tubes) to provide a functional link between trait patterns and assembly mechanisms. We also investigated whether the degree of co‐flowering depended on the floral abundance and pollination functional group (fly‐, bee‐, hummingbird‐pollinated and generalist species) of the plant species.
High floral abundance in the flowering season was associated with low trait diversity in the community. Both features increased fitness at the community level. This indicates that similar species are benefited at periods of high floral abundance, probably due to the joint attraction of generalist pollinators in this pollinator‐depauperated community. In general, rare species flowered more synchronously with the community than abundant ones, although distinct patterns emerged depending on the floral trait and pollination functional group. Furthermore, species highly synchronous and possessing similar floral colour in relation to the community had higher fitness indicating that facilitative mechanisms act favouring flowering synchrony and trait similarity.
Synthesis. Patterns of flowering synchrony and floral trait similarity indicate pollination facilitation in the studied community. Plants benefited from co‐flowering with species possessing similar floral colour via shared pollinator attraction. Thus, we empirically demonstrated some of the predictions of community assembly theory.
Patterns of flowering synchrony and floral trait similarity indicate pollination facilitation in the studied community. Plants benefited from co‐flowering with species possessing similar floral colour via shared pollinator attraction. Thus, we empirically demonstrated some of the predictions of community assembly theory.
Resume
Processos mediados por polinizadores (filtragem biótica, facilitação e competição) são comumente inferidos a partir da diversidade de atributos reprodutivos de plantas (agregação ou segregação de atributos reprodutivos dentro da comunidade). Porém, um mesmo padrão pode ser decorrente de distintos processos, o que torna difícil a predição do principal processo atuando na estruturação da comunidade. A incorporação de medidas de sucesso reprodutivo deve aumentar a associação entre padrão e processo.
Nós investigamos padrões da fenologia de floração e atributos reprodutivos (cor floral, tamanho da flor, e altura das anteras) ao longo da estação reprodutiva de uma comunidade generalizada e pobre em polinizadores. Nós utilizamos dados de sucesso reprodutivo (deposição de pólen e número de tubos polínicos) para fornecer uma associação funcional entre padrões de atributos e mecanismos estruturadores. Nós investigamos também se o grau de co‐floração de uma espécie estava relacionada a sua abundância floral e grupo funcional de polinização (polinizada por moscas, abelhas, beija‐flores ou generalista).
Meses com abundância de flores alta estavam associados a baixa diversidade funcional na comunidade. Estas duas características aumentaram o sucesso reprodutivo ao nível da comunidade. Estas evidências indicam que espécies similares entre si são beneficiadas em períodos de abundância de flores alta, provavelmente devido a atração conjunta de polinizadores generalistas nesta comunidade pobre em polinizadores. Em geral, espécies raras floresceram em maior sincronia com a comunidade que espécies abundantes, apesar deste padrão depender do atributo reprodutivo e grupo funcional de polinização. Ainda, species em alta sincronia e cor floral similar com a comunidade apresentaram maior sucesso reprodutivo, sugerindo que a facilitação atua favorescendo sincronia floral e similaridade nos atributos.
Síntese Padrões de sincronia floral e similaridade nos atributos florais evidenciam a facilitação na polinização para a comunidade estudada. Plantas se beneficiaram ao florir com espécies com cores florais parecidas ao atraírem polinizadores compartilhados. Portanto, nós demonstramos empiricamente algumas das predições da teoria de estruturação de comunidades.
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Many insects obtain gut microbes from their diet, but how a mother's foraging patterns influence the microbes found in her offspring's food remains an open question. To address this gap, we studied a ...bee that forages for pollen from multiple species of plants and may therefore acquire diverse bacteria from different plants. We tested the hypothesis that pollen diversity correlates with bacterial diversity by simultaneously characterizing these two communities in bee brood provisions for the first time. We used deep sequencing of the plant RBCL gene and the bacterial 16S rRNA gene to characterize pollen and bacterial diversity. We then tested for associations between pollen and bacterial species richness and community composition, as well as co‐occurrence of specific bacteria and pollen types. We found that both pollen and bacterial communities were extremely diverse, indicating that mother bees visit a wide variety of flowers for pollen and nectar and subsequently bring a diversity of microbes back into their nests. Pollen and bacterial species richness and community composition, however, were not correlated. Certain pollen types significantly co‐occurred with the most proportionally abundant bacteria, indicating that the plants these pollen types came from may serve as reservoirs for these bacteria. Even so, the overall diversity of these communities appears to mask these associations at a broader scale. Further study of these pollen and bacteria associations will be important for understanding the complicated relationship between bacteria and wild bees.
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Meta-barcoding of mixed pollen samples constitutes a suitable alternative to conventional pollen identification via light microscopy. Current approaches however have limitations in practicability due ...to low sample throughput and/or inefficient processing methods, e.g. separate steps for amplification and sample indexing.
We thus developed a new primer-adapter design for high throughput sequencing with the Illumina technology that remedies these issues. It uses a dual-indexing strategy, where sample-specific combinations of forward and reverse identifiers attached to the barcode marker allow high sample throughput with a single sequencing run. It does not require further adapter ligation steps after amplification. We applied this protocol to 384 pollen samples collected by solitary bees and sequenced all samples together on a single Illumina MiSeq v2 flow cell. According to rarefaction curves, 2,000-3,000 high quality reads per sample were sufficient to assess the complete diversity of 95% of the samples. We were able to detect 650 different plant taxa in total, of which 95% were classified at the species level. Together with the laboratory protocol, we also present an update of the reference database used by the classifier software, which increases the total number of covered global plant species included in the database from 37,403 to 72,325 (93% increase).
This study thus offers improvements for the laboratory and bioinformatical workflow to existing approaches regarding data quantity and quality as well as processing effort and cost-effectiveness. Although only tested for pollen samples, it is furthermore applicable to other research questions requiring plant identification in mixed and challenging samples.
ORCHESTRATED FLOWERING AND INTERSPECIFIC FACILITATION Carreño-Barrera, Javier; Núñez-Avellaneda, Luis Alberto; Sanín, Maria José ...
Annals of the Missouri Botanical Garden,
10/2020, Volume:
105, Issue:
3
Journal Article
Peer reviewed
Solitary, dioecious, and mostly endemic to Andean cloud forests, wax palms (Ceroxylon Bonpl. ex DC. spp.) are currently under worrisome conservation status. The establishment of management plans for ...their dwindling populations rely on detailed biological data, including their reproductive ecology. As in the case of numerous other Neotropical palm taxa, small beetles are assumed to be selective pollinators of wax palms, but their identity and relevance in successful fruit yield were unknown. During three consecutive reproductive seasons we collected data on population phenology and reproductive and floral biology of three syntopic species of wax palms native to the Colombian Andes. We also determined the composition of the associated flower-visiting entomofauna, quantifying the extent of the role of individual species as effective pollinators through standardized value indexes that take into consideration abundance, constancy, and pollen transport efficiency. The studied populations of C. parvifrons (Engel) H. Wendl., C. ventricosum Burret, and C. vogelianum (Engel) H. Wendl. exhibit seasonal reproductive cycles with marked temporal patterns of flower and fruit production. The composition of the associated flower-visiting entomofauna, comprised by ca. 50 morphotypes, was constant across flowering seasons and differed only marginally among species. Nonetheless, a fraction of the insect species associated with pistillate inflorescences actually carried pollen, and calculated pollinator importance indexes demonstrated that one insect species alone, Mystrops rotundula Sharp, accounted for 94%–99% of the effective pollination services for all three species of wax palms. The sequential asynchronous flowering of C. parvifrons, C. ventricosum, and C. vogelianum provides an abundant and constant supply of pollen, pivotal for the maintenance of large populations of their shared pollinators, a cooperative strategy proven effective by high fruit yield rates (up to 79%). Reproductive success might be compromised for all species by the population decline of one of them, as it would tamper with the temporal orchestration of pollen offer.
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•Climate change is predicted to cause phenological mismatches in plant-pollinator communities.•Phenologies of bees differ among species and may depend on degrees of specialization.•We find that in a ...system of Clarkia (Onagraceae), two bee pollinator species - one a Clarkia specialist, the other a generalist - differ in their within-season phenologies.•This adds to a growing body of work suggesting that phenological mismatches between plants and pollinators may be species-specific.•Future work should investigate the link between species-specific phenologies within growing seasons and phenological shifts between years.
Phenological matching between the timing of flowering and pollinator activity is critically important for the persistence of pollination systems globally. Phenological mismatch between plants and their insect pollinators can occur if flowering and adult insect activity do not occur simultaneously. There is evidence that the phenological trajectories vary among bee species, but little has been done to compare these trajectories with the phenology of the corresponding floral community. In this work, we use daily pan trapping across nine different annual Clarkia (Onagraceae) plant communities that vary in Clarkia species composition to estimate the phenological trajectory (within-season abundance curve) of the two most abundant bee pollinators - Lasioglossum incompletum, a generalist, and Hesperapis regularis, a Clarkia specialist - over the course of a Clarkia flowering season in California USA. Clarkia flower at the end of the winter annual growing season when all other winter annual plants have senesced, and therefore are phenologically separate from other flowering plants. We find that Hesperapis pollinator abundances follow the same phenological trajectory as Clarkia floral abundances in all community types. In contrast, Lasioglossum abundances do not track Clarkia floral abundance through time. Our results demonstrate that Clarkia exhibit closer phenological matching with Hesperapis than with Lasioglossum. These findings imply that pollinator communities may not respond monolithically to changes in the environment. Future research should study the phenological trajectories of plants and pollinators in different systems to determine if this pattern is common and repeatable.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Mycorrhizal associations in mycoheterotrophic plants are generally more specialized than in autotrophs. Mycoheterotrophs typically bear small, inconspicuous flowers that often self-pollinate to ...maximize seed set, although some have structurally complex flowers indicative of xenogamy. A trade-off has previously been proposed between specialization in these above- and below-ground symbioses, although empirical data are lacking.
We used next-generation DNA sequencing to compare the mycorrhizal communities from the roots of a mycoheterotrophic species, Thismia tentaculata (Thismiaceae), and its neighbouring autotrophs. We furthermore conducted detailed assessments of floral phenology and pollination ecology, and performed artificial pollination experiments to determine the breeding system.
Thismia tentaculata maintains a symbiotic association with a single arbuscular mycorrhizal Rhizophagus species. The flowers are pollinated by a single species of fungus gnats (Corynoptera, Sciaridae), which are attracted by the yellow pigments and are temporarily restrained within the perianth chamber before departing via apertures between the anthers. The plants are self-compatible but predominantly xenogamous.
Our findings demonstrate that T. tentaculata maintains highly specialized associations with pollinators and mycorrhizal fungi, both of which are widely distributed. We suggest that specialization in multiple symbiotic interactions is possible in mycoheterotrophs if redundant selective pressures are not exerted to further restrict an already constrained suite of life-history traits.
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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
The geographical range of pollinators is an important factor determining the distribution of plants with specialized pollinator interactions. Furthermore, pollinator availability can be ...critical for the success of conservation translocations of threatened flora with such interactions. Here, we investigated the pollination biology of the endangered orchid Caladenia versicolor, with the aim of improving management of wild populations and conservation translocations (artificial translocation for conservation). Using portable groups of cultivated plants to attract pollinators, we found that at natural sites C. versicolor is predominantly pollinated by food-foraging males of one species of bee, Leioproctus platycephalus (Colletidae), with only occasional visits from females or other bee species. This apparently high degree of specialization occurred despite the presence of a co-occurring bee community of > 20 species. Although previously thought to be nectarless, gas chromatography-mass spectrometry analysis of labellum secretions revealed that C. versicolor produces meagre quantities of sucrose on the upper surface of the labellum, on which some pollinators appeared to feed. Reproductive success was high in C. versicolor at both natural and translocated sites. Although C. versicolor now has a restricted range, L. platycephalus is found across a broad area of southern Australia. Thus, pollinator availability does not appear to have contributed to the rarity of C. versicolor, but the apparent reliance on L. platycephalus means that the availability of this species needs to be taken into account for conservation management and translocations.
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Based on recent molecular work by Paudyal & al., the generic limits of the Neotropical woody genus Exostema are reassessed with a view of making them more compatible with traditional, ...morphology‐based generic concepts. A wide circumscription is favoured, congruent with Paudyal & al.'s “clade B” (the Exostema‐Solenandra‐Coutarea‐Hintonia group). Thus defined, Exostema is a genus with 40 species and five natural sections and incorporates three generic splits that were proposed by Paudyal & al. To minimise nomenclatural disruption, a proposal to conserve the name Exostema Rich. against Coutarea Aubl. has been presented separately. Two new combinations at sectional rank are proposed.
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