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1. Flower morphology as a predictor of pollination mode in a biotic to abiotic pollination continuum

   https://doi.org/10.1093/aob/mcad069  

   Martínez-Gómez, Jesús ; Park, Seongjun ; Hartogs, Samantha R ; Soza, Valerie L ; Park, SeonJoo ; Di Stilio, Verónica S ( May 2023 , Annals of Botany)

   Abstract Background and Aims Wind pollination has evolved repeatedly in flowering plants, yet the identification of a wind pollination syndrome as a set of integrated floral traits can be elusive. Thalictrum (Ranunculaceae) comprises temperate perennial herbs that have transitioned repeatedly from insect to wind pollination while also exhibiting mixed pollination, providing an ideal system to test for evolutionary correlation between floral morphology and pollination mode in a biotic to abiotic continuum. Moreover, the lack of floral organ fusion across this genus additionally allows to test for specialization to pollination vectors in the absence of this feature. Methods We expanded phylogenetic sampling in the genus from a previous study using six chloroplast loci, which allowed us to test whether species cluster into distinct pollination syndromes based on floral morphology. We then used multivariate analyses on floral traits, followed by ancestral state reconstruction of the emerging flower morphotypes and determined whether these traits are evolutionarily correlated under a Bayesian framework with Brownian motion. Key Results Floral traits fell into five distinct clusters, which were reduced to three after considering phylogenetic relatedness, and were largely consistent with flower morphotypes and associated pollination vectors. Multivariate evolutionary analyses found a positive correlation between the lengths of floral reproductive structures (styles, stigmas, filaments, and anthers). Shorter reproductive structures tracked insect-pollinated species and clades in the phylogeny while longer structures tracked wind-pollinated ones, consistent with selective pressures exerted by biotic vs. abiotic pollination vectors, respectively. Conclusions While detectable suites of integrated floral traits across Thalictrum correlated with wind or insect pollination at the extremes of the morphospace distribution, a presumed intermediate, mixed pollination mode morphospace was also detected. Thus, our data broadly support the existence of detectable flower morphotypes from convergent evolution underlying pollination mode evolution in Thalictrum, presumably via different paths from an ancestral mixed pollination state. 

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2. The effectiveness of flower strips and hedgerows on pest control, pollination services and crop yield: a quantitative synthesis

   https://doi.org/10.1111/ele.13576  

   Albrecht, Matthias ; Kleijn, David ; Williams, Neal M. ; Tschumi, Matthias ; Blaauw, Brett R. ; Bommarco, Riccardo ; Campbell, Alistair J. ; Dainese, Matteo ; Drummond, Francis A. ; Entling, Martin H. ; et al ( October 2020 , Ecology Letters)

   Irwin, Rebecca (Ed.)
3. The evolution of flower longevity in unpredictable pollination environments

   https://doi.org/10.1111/jeb.13936  

   Xu, Kuangyi ; Servedio, Maria R. ( September 2021 , Journal of Evolutionary Biology)

   Pollination requires a flower to remain open for long enough to allow for the arrival of pollinators. However, maintaining flowers costs energy and resources. Therefore, flower longevity, the length of time a flower remains viable, is critical for the outcome of plant reproduction. Although previous studies showed that the evolution of flower longevity depends on the rates of pollen deposition and removal, whether plants should increase or decrease flower life span when the pollination environment is unpredictable has not been explored. Moreover, the common hypothesis that an unpredictable pollination environment should select for increased flower longevity may be too simplistic since there is no distinction drawn between the effects of spatial and temporal variation. Adopting evolutionary game theory, we investigate the evolution of flower longevity under three types of variation: spatial heterogeneity, daily fluctuations within a flowering season and yearly fluctuations between flowering seasons. We find that spatial heterogeneity often selects for a shorter flower lifespan, while temporal fluctuations of fitness accrual rates at both daily and yearly time scales tends to favour greater longevity, although daily and yearly fluctuations have somewhat different effects. However, the presence of correlation between female and male fitness accrual rates seems to have no effect on flower longevity. Our work suggests that explicit measurements of spatial and temporal variation in both female and male functions may provide a better understanding of the evolution of flower longevity and reproduction.

    

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4. Flower-visiting bat species contribute unequally toward agricultural pollination ecosystem services in southern Thailand

   https://doi.org/10.1111/btp.12401  

   Stewart, Alyssa B. ; Dudash, Michele R. ( March 2017 , Biotropica)
5. Competition for pollination and isolation from mates differentially impact four stages of pollination in a model grassland perennial

   https://doi.org/10.1111/1365-2745.13562  

   Richardson, Lea K. ; Gallagher, M. Kate ; Hayes, Tracie E. ; Gallinat, Amanda S. ; Kiefer, Gretel ; Manion, Kristen ; Jenkins, Miriam ; Diersen, Greg ; Wagenius, Stuart ; Rafferty, ed., Nicole ( November 2020 , Journal of Ecology)

   Species that persist in small populations isolated by habitat destruction may experience reproductive failure. Self‐incompatible plants face dual threats of mate‐limitation and competition with co‐flowering plants for pollination services. Such competition may lower pollinator visitation, increase heterospecific pollen transfer and reduce the likelihood that a visit results in successful pollination.

   To understand how isolation from mates and competition with co‐flowering species contribute to reproductive failure in fragmented habitat, we conducted an observational study of a tallgrass prairie perennialEchinacea angustifolia. We quantified the isolation of focal individuals from mates, characterized species richness and counted inflorescences within 1 m radius, observed pollinator visitation, collected pollinators, quantified pollen loads on pollinators and onEchinaceastigmas, and measured pollination success. Throughout the season, we sampled 223 focal plants across 10 remnant prairie sites.

   We present evidence that both co‐flowering species and isolation from mates substantially limit reproduction inEchinacea. As the flowering season progressed, the probability of pollinator visitation to focal plants decreased and evidence for pollen‐limited reproduction increased. Pollinators were most likely to visitEchinaceaplants from low‐richness floral neighbourhoods with close potential mates, or plants from high‐richness neighbourhoods with distant potential mates. Frequent visitation only increased pollination success in the former case, likely becauseEchinaceain high‐richness floral neighbourhoods received low‐quality visits.

   Synthesis. InEchinacea,reproduction was limited by isolation from potential mates and the richness of co‐flowering species. These aspects of the floral neighbourhood influenced pollinator visitation and pollination success, although conditions that predicted high visitation did not always lead to high pollination success. These results reveal how habitat modification and destruction, which influence floral neighbourhood and isolation from conspecific mates, can differentially affect various stages of reproductive biology in self‐incompatible plants. Our results suggest that prairie conservation and restoration efforts that promote patches of greater floral diversity may improve reproductive outcomes in fragmented habitats.

    

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