Author
Rachel L. Vannette
Other affiliations: Stanford University, University of Michigan, University of California, Berkeley
Bio: Rachel L. Vannette is an academic researcher from University of California, Davis. The author has contributed to research in topics: Nectar & Pollinator. The author has an hindex of 21, co-authored 58 publications receiving 1612 citations. Previous affiliations of Rachel L. Vannette include Stanford University & University of Michigan.
Topics: Nectar, Pollinator, Microbiome, Biology, Pollination
Papers
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TL;DR: It is suggested that it is necessary to understand the determinants of microbial species composition in nectar and their differential modification of floral rewards to explain the mutual benefits that plants and pollinators gain from each other.
Abstract: Mutualistic interactions are often subject to exploitation by species that are not directly involved in the mutualism. Understanding which organisms act as such ‘third-party’ species and how they d...
213 citations
TL;DR: It is argued that improved predictions can be achieved by decomposing species' niches into three components: overlap, impact and requirement, and shown that niches can be twice as predictive when separated into components.
Abstract: The way species affect one another in ecological communities often depends on the order of species arrival. The magnitude of such historical contingency, known as priority effects, varies across species and environments, but this variation has proven difficult to predict, presenting a major challenge in understanding species interactions and consequences for community structure and function. Here, we argue that improved predictions can be achieved by decomposing species' niches into three components: overlap, impact and requirement. Based on classic theories of community assembly, three hypotheses that emphasise related, but distinct influences of the niche components are proposed: priority effects are stronger among species with higher resource use overlap; species that impact the environment to a greater extent exert stronger priority effects; and species whose growth rate is more sensitive to changes in the environment experience stronger priority effects. Using nectar-inhabiting microorganisms as a model system, we present evidence that these hypotheses complement the conventional hypothesis that focuses on the role of environmental harshness, and show that niches can be twice as predictive when separated into components. Taken together, our hypotheses provide a basis for developing a general framework within which the magnitude of historical contingency in species interactions can be predicted.
199 citations
TL;DR: The presence of fungi and bacteria in the nectar of a coflowering plant community is examined, the volatiles produced by common nectar microbes are characterized, and electrophysiological and behavioral responses of honey bees to microbial volatile are examined.
Abstract: The plant microbiome can influence plant phenotype in diverse ways, yet microbial contribution to plant volatile phenotype remains poorly understood We examine the presence of fungi and bacteria in the nectar of a coflowering plant community, characterize the volatiles produced by common nectar microbes and examine their influence on pollinator preference Nectar was sampled for the presence of nectar-inhabiting microbes We characterized the headspace of four common fungi and bacteria in a nectar analog We examined electrophysiological and behavioral responses of honey bees to microbial volatiles Floral headspace samples collected in the field were surveyed for the presence of microbial volatiles Microbes commonly inhabit floral nectar and the common species differ in volatile profiles Honey bees detected most microbial volatiles tested and distinguished among solutions based on volatiles only Floral headspace samples contained microbial-associated volatiles, with 2-ethyl-1-hexanol and 2-nonanone - both detected by bees - more often detected when fungi were abundant Nectar-inhabiting microorganisms produce volatile compounds, which can differentially affect honey bee preference The yeast Metschnikowia reukaufii produced distinctive compounds and was the most attractive of all microbes compared The variable presence of microbes may provide volatile cues that influence plant-pollinator interactions
145 citations
TL;DR: The authors found that the positive effects of dispersal on beta diversity may have been greatly underappreciated and suggested that this unexpected pattern might have resulted from stronger priority effects under increased dispersal.
Abstract: Dispersal is considered a key driver of beta diversity, the variation in species composition among local communities, but empirical tests remain limited. We manipulated dispersal of nectar-inhabiting bacteria and yeasts via flower-visiting animals to examine how dispersal influenced microbial beta diversity among flowers. Contrary to the prevailing view that dispersal lowers beta diversity, we found beta diversity was highest when dispersal was least limited. Our analysis suggested that this unexpected pattern might have resulted from stronger priority effects under increased dispersal. Dispersal is highly stochastic, generating variability in species arrival history and consequently the potential for community divergence via priority effects, in these and likely many other microbial, plant, and animal communities. Yet most previous experiments eliminated this possibility. We suggest that the positive effects of dispersal on beta diversity, like the one we report here, may have been greatly underappreciated.
116 citations
TL;DR: It is suggested that gut microbes may not only affect the bees’ health as symbionts, but that some of the microbes may possibly affect the efficacy of A. mellifera as pollinators by altering nectar chemistry and influencing their foraging behavior.
Abstract: The gut microflora of the honey bee, Apis mellifera, is receiving increasing attention as a potential determinant of the bees' health and their efficacy as pollinators. Studies have focused primarily on the microbial taxa that appear numerically dominant in the bee gut, with the assumption that the dominant status suggests their potential importance to the bees' health. However, numerically minor taxa might also influence the bees' efficacy as pollinators, particularly if they are not only present in the gut, but also capable of growing in floral nectar and altering its chemical properties. Nonetheless, it is not well understood whether honey bees have any feeding preference for or against nectar colonized by specific microbial species. To test whether bees exhibit a preference, we conducted a series of field experiments at an apiary using synthetic nectar inoculated with specific species of bacteria or yeast that had been isolated from the bee gut, but are considered minor components of the gut microflora. These species had also been found in floral nectar. Our results indicated that honey bees avoided nectar colonized by the bacteria Asaia astilbes, Erwinia tasmaniensis, and Lactobacillus kunkeei, whereas the yeast Metschnikowia reukaufii did not affect the feeding preference of the insects. Our results also indicated that avoidance of bacteria-colonized nectar was caused not by the presence of the bacteria per se, but by the chemical changes to nectar made by the bacteria. These findings suggest that gut microbes may not only affect the bees' health as symbionts, but that some of the microbes may possibly affect the efficacy of A. mellifera as pollinators by altering nectar chemistry and influencing their foraging behavior.
111 citations
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TL;DR: Recent developments in rhizosphere research are discussed in relation to assessing the contribution of the micro- and macroflora to sustainable agriculture, nature conservation, the development of bio-energy crops and the mitigation of climate change.
Abstract: The rhizosphere is the interface between plant roots and soil where interactions among a myriad of microorganisms and invertebrates affect biogeochemical cycling, plant growth and tolerance to biotic and abiotic stress. The rhizosphere is intriguingly complex and dynamic, and understanding its ecology and evolution is key to enhancing plant productivity and ecosystem functioning. Novel insights into key factors and evolutionary processes shaping the rhizosphere microbiome will greatly benefit from integrating reductionist and systems-based approaches in both agricultural and natural ecosystems. Here, we discuss recent developments in rhizosphere research in relation to assessing the contribution of the micro- and macroflora to sustainable agriculture, nature conservation, the development of bio-energy crops and the mitigation of climate change.
2,332 citations
University of Wisconsin-Madison1, University of Hawaii2, University of Kiel3, Cornell University4, Max Planck Society5, Pasteur Institute6, Stanford University7, University of Helsinki8, University of Würzburg9, University of California, Berkeley10, University of New South Wales11, Harvard University12, California Institute of Technology13, University of Colorado Boulder14, University of Southern California15, University of North Carolina at Chapel Hill16, University of Connecticut17, Duke University18
TL;DR: Recent technological and intellectual advances that have changed thinking about five questions about how have bacteria facilitated the origin and evolution of animals; how do animals and bacteria affect each other’s genomes; how does normal animal development depend on bacterial partners; and how is homeostasis maintained between animals and their symbionts are highlighted.
Abstract: In the last two decades, the widespread application of genetic and genomic approaches has revealed a bacterial world astonishing in its ubiquity and diversity. This review examines how a growing knowledge of the vast range of animal–bacterial interactions, whether in shared ecosystems or intimate symbioses, is fundamentally altering our understanding of animal biology. Specifically, we highlight recent technological and intellectual advances that have changed our thinking about five questions: how have bacteria facilitated the origin and evolution of animals; how do animals and bacteria affect each other’s genomes; how does normal animal development depend on bacterial partners; how is homeostasis maintained between animals and their symbionts; and how can ecological approaches deepen our understanding of the multiple levels of animal–bacterial interaction. As answers to these fundamental questions emerge, all biologists will be challenged to broaden their appreciation of these interactions and to include investigations of the relationships between and among bacteria and their animal partners as we seek a better understanding of the natural world.
2,103 citations
TL;DR: Both stochastic and deterministic components embedded in various ecological processes, including selection, dispersal, diversification, and drift are described.
Abstract: Understanding the mechanisms controlling community diversity, functions, succession, and biogeography is a central, but poorly understood, topic in ecology, particularly in microbial ecology. Although stochastic processes are believed to play nonnegligible roles in shaping community structure, their importance relative to deterministic processes is hotly debated. The importance of ecological stochasticity in shaping microbial community structure is far less appreciated. Some of the main reasons for such heavy debates are the difficulty in defining stochasticity and the diverse methods used for delineating stochasticity. Here, we provide a critical review and synthesis of data from the most recent studies on stochastic community assembly in microbial ecology. We then describe both stochastic and deterministic components embedded in various ecological processes, including selection, dispersal, diversification, and drift. We also describe different approaches for inferring stochasticity from observational diversity patterns and highlight experimental approaches for delineating ecological stochasticity in microbial communities. In addition, we highlight research challenges, gaps, and future directions for microbial community assembly research.
1,071 citations
TL;DR: The order and timing of species immigration during community assembly can affect species abundances at multiple spatial scales, and two requirements must be satisfied for historical contingency to occur: the regional pool contains species that can together cause priority effects, and local dynamics are rapid enough for early-arrived species to preempt or modify niches before other species arrive.
Abstract: The order and timing of species immigration during community assembly can affect species abundances at multiple spatial scales. Known as priority effects, these effects cause historical contingency in the structure and function of communities, resulting in alternative stable states, alternative transient states, or compositional cycles. The mechanisms of priority effects fall into two categories, niche preemption and niche modification, and the conditions for historical contingency by priority effects can be organized into two groups, those regarding regional species pool properties and those regarding local population dynamics. Specifically, two requirements must be satisfied for historical contingency to occur: The regional pool contains species that can together cause priority effects, and local dynamics are rapid enough for early-arriving species to preempt or modify niches before other species arrive. Organizing current knowledge this way reveals an outstanding key question: How are regional species ...
1,051 citations
University of Vienna1, University of Edinburgh2, Massey University3, Newcastle University4, University of Copenhagen5, University of Glasgow6, Massachusetts Institute of Technology7, Boston College8, Fred Hutchinson Cancer Research Center9, University of Aberdeen10, San Diego State University11, Institut national de la recherche agronomique12, University of Birmingham13, Agricultural Research Organization, Volcani Center14, University of Jena15, University of Lausanne16, University of Warwick17, University of Amsterdam18, Delft University of Technology19, Temple University20, Technical University of Denmark21, Columbia University22
TL;DR: In this paper, the authors argue that the ability to predict and manage the function of these highly complex, dynamically changing communities is limited, and that close coordination of experimental data collection and method development with mathematical model building is needed to achieve significant progress in understanding of microbial dynamics and function.
Abstract: The importance of microbial communities (MCs) cannot be overstated. MCs underpin the biogeochemical cycles of the earth’s soil, oceans and the atmosphere, and perform ecosystem functions that impact plants, animals and humans. Yet our ability to predict and manage the function of these highly complex, dynamically changing communities is limited. Building predictive models that link MC composition to function is a key emerging challenge in microbial ecology. Here, we argue that addressing this challenge requires close coordination of experimental data collection and method development with mathematical model building. We discuss specific examples where model–experiment integration has already resulted in important insights into MC function and structure. We also highlight key research questions that still demand better integration of experiments and models. We argue that such integration is needed to achieve significant progress in our understanding of MC dynamics and function, and we make specific practical suggestions as to how this could be achieved.
552 citations