The Role of Alien Species on Plant-Floral Visitor Network Structure in Invaded Communities

This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. The interactions between pairs of native and alien plants via shared use of pollinators have been widely studied. Community level studies however, are necessary in order to fully understand the factors and mechanisms that facilitate successful plant invasion, but these are still scarce. Specifically, few community level studies have considered how differences in invasion level (alien flower abundance), and degree of floral trait similarity between native and invasive species, mediate effects on native plant-pollinator communities. Here, we evaluated the role of alien species on overall plant-floral visitor network structure, and on species-level network parameters, across nine invaded coastal communities distributed along 205 km in Yucatán, México that vary in alien species richness and flower abundance. We further assessed the potential the role of alien plant species on plant-floral visitor network structure and robustness via computational simulation of native and invasive plant extinction scenarios. We did not find significant differences between native and alien species in their functional floral phenotypes or in their visitation rate and pollinator community composition in these invaded sites. Variation in the proportion of alien plant species and flower abundance across sites did not influence plant-pollinator network structure. Species-level network parameters (i.e., normalized degree and nestedness contribution) did not differ between native and alien species. Furthermore, our simulation analyses revealed that alien species are functionally equivalent to native species and contribute equally to network structure and robustness. Overall, our results suggest that high levels of floral trait similarity and pollinator use overlap may help facilitate the integration of alien species into native plant-pollinator networks. As a result, alien species may also play a similar role than that of natives in the structure and stability of native plant and pollinator communities in the studied coastal sand dune ecosystem

Técnicas bibliométricas para la autoevaluación de los grupos de investigación de la Universidad Autónoma de Yucatán, México

En este trabajo se presenta la metodología empleada en la autoevaluación de los Cuerpos Académicos del Campus de Ciencias Biológicas y Agropecuarias de la Universidad Autónoma de Yucatán, México, a través de parámetros cuantitativos que permitieron visualizar la calidad y cantidad de la producción académica. Para llevar a cabo dicha autoevaluación se empleó información bibliométrica obtenida de la base de datos Scopus©, del período enero 2000 a julio 2016. Se concluye que la metodología propuesta en este estudio puede ser útil para optimizar procesos de planeación y mejora continua de los cuerpos académicos de universidades públicas de México, así como utilizar en estudios futuros la metodología cualitativa para mejorar el proceso de autoevaluación

La Polinización autónoma alivia la limitación por polen en la especie endémica Cienfuegosia yucatanensis Millsp ( Malvaceae)

Background: Self-compatibility is common on endemic plant species, but pollen limitation and self-pollination could be risk factors. Study species: The endemic Cienfuegosia yucatanensis (Malvaceae), whose distribution is mainly restricted to the north coast of the peninsula of Yucatán, México. Questions: a) Are flowers of C. yucatanensis autonomous for pollination? b) Are C. yucatanensis fruit or seed-set limited by pollen deposition? and, c) Is there evidence of early inbreeding depression in C. yucatanensis? Study sites and dates: Two sites in the north of the peninsula of Yucatán in a seasonally dry scrubland, in the rainy season of 2013 and 2014. Methods: Number of flowers and fruits were weekly recorded. Flowers were collected to count the number of conspecific pollen load and the number of pollen tubes. Autonomous pollination and pollen limitation were evaluated with a hand-pollination experiment. Inbreeding depression on fruit and seed production, and seed weight was evaluated. Results: Flower and fruit production occur simultaneously and last from August to October. Conspecific pollen deposition on stigmas occurred through the whole flowering season and a maximum of pollen tubes was observed in August. Autonomous pollination treatment lead to similar fruit and seed production than cross-pollination, but open pollination produced significantly more seeds. No significant differences among self- and cross-pollination treatments on fruit and seed production or seed weight, were found. Conclusions: Our results suggest that self-compatibility combined with a relatively efficient autonomous pollination, are suitable mechanisms for the reproductive assurance in C. yucatanensis, with no apparent effects of early inbreeding depression.Peer reviewe

Spatially inconsistent direct and indirect effects of herbivory on floral traits and pollination success in a tropical shrub

Investigations on plant–animal interactions have traditionally focused on single interactions at a time (e.g. herbivory, pollination), yet plant fitness is generally influenced in complex ways by several interactions operating concurrently, and very little is known on the degree of spatial consistency of the direct and indirect effects that link different interactions. This paper evaluates experimentally whether direct and indirect effects of herbivory on male and female flower size and pollination success of the monoecious tropical shrub Cnidoscolus aconitifolius (Euphorbiaceae) remain consistent at three distant regions in Yucatan (southeastern Mexico). Plants were subjected to different levels of leaf defoliation, and treatment effects on floral traits (corolla area, corolla tube length, pollen production), and male and female components of pollina- tion success (percent pollen removal, number of pollen tubes) were subsequently measured to evaluate the indirect effect of herbivory on plant reproductive success via pollination. Defoliation had significant direct effects on floral traits, but its indirect effects differed between the male and female components of pollination success. Moreover, the relationships between defoliation, floral traits and male and female pollination success varied spatially (i.e. between regions), although they were frequently more spatially-consistent for male success than for female success. Results from this study stress the importance of explicitly testing for spatial variation in direct and indirect effects arising from plant-animal interactionsPeer reviewe

Impacts of Plant Invasions in Native Plant–Pollinator Networks

The disruption of mutualisms by invasive species has consequences for biodiversity loss and ecosystem function. Although invasive plant effects on the pollination of individual native species has been the subject of much study, their impacts on entire plant–pollinator communities are less understood. Community-level studies on plant invasion have mainly focused on two fronts: understanding the mechanisms that mediate their integration; and their effects on plant–pollinator network structure. Here we briefly review current knowledge and propose a more unified framework for evaluating invasive species integration and their effects on plant–pollinator communities. We further outline gaps in our understanding and propose ways to advance knowledge in this field. Specifically, modeling approaches have so far yielded important predictions regarding the outcome and drivers of invasive species effects on plant communities. However, experimental studies that test these predictions in the field are lacking. We further emphasize the need to understand the link between invasive plant effects on pollination network structure and their consequences for native plant population dynamics (population growth). Integrating demographic studies with those on pollination networks is thus key in order to achieve a more predictive understanding of pollinator-mediated effects of invasive species on the persistence of native plant biodiversity

Pollen on stigmas as proxies of pollinator competition and facilitation: complexities, caveats and future directions

• Background Pollen transfer via animals is necessary for reproduction by ~80 % of flowering plants, and most of these plants live in multispecies communities where they can share pollinators. While diffuse plant–pollinator interactions are increasingly recognized as the rule rather than the exception, their fitness consequences cannot be deduced from flower visitation alone, so other proxies, functionally closer to seed production and amenable for use in a broad variety of diverse communities, are necessary. • Scope We conceptually summarize how the study of pollen on stigmas of spent flowers can reflect key drivers and functional aspects of the plant–pollinator interaction (e.g. competition, facilitation or commensalism). We critically evaluate how variable visitation rates and other factors (pollinator pool and floral avoidance) can give rise to different relationships between heterospecific pollen and (1) conspecific pollen on the stigma and (2) conspecific tubes/grain in the style, revealing the complexity of potential interpretations. We advise on best practices for using these proxies, noting the assumptions and caveats involved in their use, and explicate what additional data are required to verify interpretation of given patterns. • Conclusions We conclude that characterizing pollen on stigmas of spent flowers provides an attainable indirect measure of pollination interactions, but given the complex processes of pollen transfer that generate patterns of conspecific–heterospecific pollen on stigmas these cannot alone determine whether competition or facilitation are the underlying drivers. Thus, functional tests are also needed to validate these hypotheses. Key words: Conspecific pollen, heterospecific pollen, plant–plant interactions, plant–pollinator network, pollination, pollinator sharing, pollen tube, pollen transfer, stigmatic pollen load, visitation networkPeer reviewe

Integrating Floral Trait and Flowering Time Distribution Patterns Help Reveal a More Dynamic Nature of Co-Flowering Community Assembly Processes

Species\u27 floral traits and flowering times are known to be the major drivers of pollinator-mediated plant–plant interactions in diverse co-flowering communities. However, their simultaneous role in mediating plant community assembly and plant–pollinator interactions is still poorly understood. Since not all species flower at the same time, inference of facilitative and competitive interactions based on floral trait distribution patterns should account for fine phenological structure (intensity of flowering overlap) within co-flowering communities. Such an approach may also help reveal the simultaneous action of competitive and facilitative interactions in structuring co-flowering communities. Here we used modularity within a co-flowering network context, as a novel approach to detect convergent and/or over-dispersed patterns in floral trait distribution and pollinator sharing. Specifically, we evaluate differences in floral trait and pollinator distribution patterns within (high temporal flowering overlap) and among co-flowering modules (low temporal flowering overlap). We further evaluate the consistency of observed floral trait and pollinator sharing distribution patterns across space (three geographical regions) and time (dry and rainy seasons). We found that floral trait similarity was significantly higher in plant species within co-flowering modules than in species among them. This suggests pollinator facilitation may lead to floral trait convergence, but only within co-flowering modules. However, our results also revealed seasonal and spatial shifts in the underlying interactions (facilitation or competition) driving co-flowering assembly, suggesting that the prevalent dominant interactions are not static. Synthesis. Overall, we provide strong evidence showing that the use of flowering time and floral trait distribution alone may be insufficient to fully uncover the role of pollinator-mediated interactions in community assembly. Integrating this information along with patterns of pollinator sharing will greatly help reveal the simultaneous action of facilitative and competitive pollinator-mediated interactions in co-flowering communities. The spatial and temporal variation in flowering and trait distribution patterns observed further emphasize the importance of adopting a more dynamic view of community assembly processes