Publications

Selected Articles

Pollinator Microbiomes

Do amino and fatty acid profiles of pollen provisions correlate with bacterial microbiomes in the…

May 2, 2022

Pollinator Microbiomes

(More than) Hitchhikers through the network: the shared microbiome of bees and flowers

Apr 28, 2021

Pollinator Microbiomes

Drivers, Diversity, and Functions of the Solitary-Bee Microbiota

Dec 28, 2019

Full list of Publications

Feel free to contact us for any reprints of the articles!

2022

• Casanelles Abella, J., Keller, A., Müller, S., Aleixo, C., Alós Orti, M., {Chiron, F. andand L., Pinho, P., Samson, R., Tryjanowski, P., Van Mensel, A., Villarroya-Villalba, L., Pellissier, L. & Moretti, M., 2022.Wild bee larval food composition in five European cities. Ecology, P. in press.
• Ollerton, J., Trunschke, J., Havens, K., Landaverde-González, P., Keller, A., Gilpin, A.-M., Rech, A.R., Baronio, G.J., Phillips, B., Mackin, C., Stanley, D.A., Treanore, E., Baker, E., Rotheray, E.L., Erickson, E., Fornoff, F., Brearley, F.Q., Ballantyne, G., Iossa, G., Stone, G.N., Bartomeus, I., Stockan, J.A., Leguizamón, J., Prendergast, K., Rowley, L., Giovanetti, M., de Oliveira Bueno, R., Wesselingh, R.A., Mallinger, R., Edmondson, S., Howard, S.R., Leonhardt, S.D., Rojas-Nossa, S.V., Brett, M., Joaqui, T., Antoniazzi, R., Burton, V.J., Feng, H.-H., Tian, Z.-X., Xu, Q., Zhang, C., Shi, C.-L., Huang, S.-Q., Cole, L.J., Bendifallah, L., Ellis, E.E., Hegland, S.J., Díaz, S.S., Lander, T., Mayr, A.V., Katzer, S., Dawson, R., Eeraerts, M., Armbruster, W.S., Walton, B., Adjlane, N., Falk, S., Mata, L., Geiger, A.G., Carvell, C., Wallace, C., Ratto, F., Barberis, M., Kahane, F., Connop, S., Stip, A., Sigrist, M.R., Vereecken, N.J., Klein, A.-M., Baldock, K.C. & Arnold, S.E.J., 2022.Pollinator-flower interactions in gardens during the COVID-19 pandemic lockdown of 2020. Journal of Pollination Ecology, P. in press.
• Bell, K.L., Turo, K.J., Lowe, A., Nota, K., Keller, A., Encinas-Viso, F., Parducci, L., Richardson, R.T., Leggett, R.M., Brosi, B.J., Burgess, K.S., Suyama, Y. & de Vere, N., 2022.Plants, pollinators and their interactions under global ecological change: The role of pollen DNA metabarcoding. Molecular Ecology, n/a(n/a). Available at: https://onlinelibrary.wiley.com/doi/abs/10.1111/mec.16689.

  Abstract Anthropogenic activities are triggering global changes in the environment, causing entire communities of plants, pollinators and their interactions to restructure, and ultimately leading to species declines. To understand the mechanisms behind community shifts and declines, as well as monitoring and managing impacts, a global effort must be made to characterize plant–pollinator communities in detail, across different habitat types, latitudes, elevations, and levels and types of disturbances. Generating data of this scale will only be feasible with rapid, high-throughput methods. Pollen DNA metabarcoding provides advantages in throughput, efficiency and taxonomic resolution over traditional methods, such as microscopic pollen identification and visual observation of plant–pollinator interactions. This makes it ideal for understanding complex ecological networks and their responses to change. Pollen DNA metabarcoding is currently being applied to assess plant–pollinator interactions, survey ecosystem change and model the spatiotemporal distribution of allergenic pollen. Where samples are available from past collections, pollen DNA metabarcoding has been used to compare contemporary and past ecosystems. New avenues of research are possible with the expansion of pollen DNA metabarcoding to intraspecific identification, analysis of DNA in ancient pollen samples, and increased use of museum and herbarium specimens. Ongoing developments in sequencing technologies can accelerate progress towards these goals. Global ecological change is happening rapidly, and we anticipate that high-throughput methods such as pollen DNA metabarcoding are critical for understanding the evolutionary and ecological processes that support biodiversity, and predicting and responding to the impacts of change.
• König, S., Krauss, J., Keller, A., Bofinger, L. & Steffan-Dewenter, I., 2022.Phylogenetic relatedness of food plants reveals highest insect herbivore specialisation at intermediate temperatures along a broad climatic gradient. Global Change Biology, P. in press.
• Cannizzaro, C., Keller, A., Wilson, R.S., Elliott, B., Newis, R., Ovah, R., Inae, K., Kerlin, D.H., Bar, I., Kämper, W., Shapcott, A. & Wallace, H.M., 2022.Forest landscapes increase diversity of honeybee diets in the tropics. Forest Ecology and Management, P. in press.
• Leonhardt, S.D., Peters, B. & Keller, A., 2022.Do amino and fatty acid profiles of pollen provisions correlate with bacterial microbiomes in the mason bee Osmia bicornis?. Philosophical Transactions of the Royal Society B, P. in press.
• Peters, B., Keller, A. & Leonhardt, S.D., 2022.Diets maintained in a changing world: Does land-use intensification alter wild bee communities by selecting for flexible generalists?. Ecology and Evolution, P. in press.
• Boff, S., Keller, A., Raizer, J. & Lupi, D., 2022.Decreased efficiency of pollen collection due to Sulfoxaflor exposure leads to a reduction in the size of bumble bee workers in late European summer. Frontiers in Ecology and Evolution, 10. Available at: https://www.frontiersin.org/articles/10.3389/fevo.2022.842563.

  Bumble bees (Bombus terrestris) are important pollinators of wild and crop plants. Despite their importance in the process of fruit and seed production on crop sites, their activity may be impaired due to exposure to pesticides. This species has a yearly life cycle and colony success may rely on effective foraging of workers on ruderal plants late in summer when most crops are no longer flowering. In the current study, we investigated the effect of chronic exposure to Sulfoxaflor on aspects of the foraging behavior of bumble bees and whether Sulfoxaflor influences the body size of workers of B. terrestris in a crop landscape. We found that 2 weeks of continuous exposure to Sulfoxaflor influenced workers’ foraging dynamics and collection of resources. However, there was no evidence that the 5 ppb dose of the pesticide impacted the ability of bees to handle flowers with different traits. Workers from colonies exposed to Sulfoxaflor were smaller. The effect on worker size may be explained as a consequence of the reduced pollen income per unit of worker foraging. Thus, if the effects of Sulfoxaflor applied directly to crops had the same effect as that observed on commercial bumble bees after our chronic exposure, it might negatively impact colony success due to the impact on pollen collection and the reduction in the size of workers.
• Parreno, M., Alaux, C., Brunet, J.-L., Butschkau, S., Buydens, L., Filipiak, M., Henry, M., Keller, A., Klein, A.-M., Kuhlmann, M., Leroy, C., Meeus, I., Palmer-Young, E., Piot, N., Requier, F., Ruedenauer, F., Smagghe, G., Stevenson, P. & Leonhardt, S., 2022.Critical links between biodiversity, nutrition and health in wild bee conservation. Trends in Ecology and Evolution, P. in press.

2021

• Campos, M.G., Anjos, O., Chica, M., Campoy, P., Nozkova, J., Almaraz-Abarca, N., Barreto, L.M.R.C., Nordi, J.C., Estevinho, L.M., Pascoal, A., Paula, V.B., Chopina, A., Dias, L.G., j. Tešić, Živoslav L., Mosić, M.D., Kostić, A. Ž., Pešić, M.B., Milojković-Opsenica, D.M., Sickel, W., Ankenbrand, M.J., Grimmer, G., Steffan-Dewenter, I., Keller, A., Förster, F., Tananaki, C.H., Liolios, V., Kanelis, D., Rodopoulou, M.-A., Thrasyvoulou, A., Paulo, L., Kast, C., Lucchetti, M.A., Glauser, G., Lokutova, O., de Almeida-Muradian, L.B., Szczęsna, T. & Carreck, N.L., 2021.Standard methods for pollen research. Journal of Apicultural Research, 60(4), Pp. 1–109.
• Albrecht, J., Peters, M.K., Classen, A., Becker, J.N., Behler, C., Ensslin, A., Ferger, S.W., Gebert, F., Helbig-Bonitz, M., Kindeketa, W.J., Mayr, A.V., {Njovu, H.K.P., Pommer, U., Röder, J., Rutten, G., Schellenberger Costa, D., Sierra-Cornejo, N., Vogeler, A., Vollstädt, M.G.R., Dulle, H.I., Eardley, C.D., Howell, K.M., Keller, A., Peters, R.S., Kakengi, V., Hemp, C., Zhang, J., Manning, P., Müller, T., Böhning-Gaese, K., Brandl, R., Hertel, D., Kiese, R., Kleyer, M., Kuzyakov, Y., Nauss, T., Tschapka, M., Fischer, M., Hemp, A., Steffan-Dewenter, I. & Schleuning, M., 2021.Species richness is more important for ecosystem functioning than species turnover along an elevational gradient. Nature Ecology and Evolution, P. in press.
• Too, C.C., Ong, K.S., Lee, S.M., Yule, C.M. & Keller, A., 2021.Putative roles of bacteria in the carbon and nitrogen cycles in a tropical peat swamp forest. Basic and Applied Ecology, Special issue: Predictors of microbiomes.
• Quaresma, A., Brodschneider, R., Gratzer, K., Gray, A., Keller, A., Kilpinen, O., Rufino, J., van der Steen, J., Vejsnaes, F. & Pinto, M.A., 2021.Preservation methods of honey-bee collected pollen are not a source of bias in ITS2 metabarcoding. Environmental Monitoring and Assessment, P. in press.
• Elliott, B., Wilson, R., Shapcott, A., Keller, A., Newis, R., Cannizzaro, C., Burwell, C., Smith, T., Leonhardt, S.D., Kämper, W. & Wallace, H., 2021.Pollen diets and niche overlap of honey bees and native bees in protected areas. Basic and Applied Ecology, Special issue: Sequence based molecular ecology.
• Imhoff, J.F., Rahn, T., Künzel, S., Keller, A. & Neulinger, S.C., 2021.Osmotic adaptation and compatible solute biosynthesis of phototrophic bacteria as revealed from genome analyses. Microorganisms, 9(1), P. 46. Available at: https://www.mdpi.com/2076-2607/9/1/46.

  Osmotic adaptation and accumulation of compatible solutes is a key process for life at high osmotic pressure and elevated salt concentrations. Most important solutes that can protect cell structures and metabolic processes at high salt concentrations are glycine betaine and ectoine. The genome analysis of more than 130 phototrophic bacteria shows that biosynthesis of glycine betaine is common among marine and halophilic phototrophic Proteobacteria and their chemotrophic relatives, as well as in representatives of Pirellulaceae and Actinobacteria, but are also found in halophilic Cyanobacteria and Chloroherpeton thalassium. This ability correlates well with the successful toleration of extreme salt concentrations. Freshwater bacteria in general lack the possibilities to synthesize and often also to take up these compounds. The biosynthesis of ectoine is found in the phylogenetic lines of phototrophic Alpha- and Gammaproteobacteria, most prominent in the Halorhodospira species and a number of Rhodobacteraceae. It is also common among Streptomycetes and Bacilli. The phylogeny of glycine-sarcosine methyltransferase (GMT) and diaminobutyrate-pyruvate aminotransferase (EctB) sequences correlate well with otherwise established phylogenetic groups. Most significantly, GMT sequences of cyanobacteria form two major phylogenetic branches and the branch of Halorhodospira species is distinct from all other Ectothiorhodospiraceae. A variety of transport systems for osmolytes are present in the studied bacteria.
• Gallagher, R., Falster, D.S., Maitner, B., Enquist, B., Ankenbrand, M., Balk, M., Bland, L., Boyle, B., Bravo, C., Cavazos, B., Fadrique, B., Feng, X., Halbritter, A., Hammock, J., Hogan, J.A., Iversen, C., Jochum, M., Kattge, J., Keller, A., Madin, J., Manning, P., McCormack, L., Michaletz, S., Park, D., Pearse, W., Penone, C., Perez, T., Pineda-Munoz, S., Poelen, J., Ray, C., Salguero-Gomez, R., Sauquet, H., Schneider, F., Spasojevic, M.J., Vandvik, V., Violle, C. & Weiss, K., 2021.Open Science principles for accelerating trait-based science across the Tree of Life. Nature Ecology \& Evolution, Pp. 294–303.
• Wilson, R., Keller, A., Shapcott, A., Leonhardt, S.D., Sickel, W., Hardwick, J.L., Heard, T., Kaluza, B.F. & and Wallace, H., 2021.Many small rather than few large sources identified in long-term bee pollen diets in agroecosystems. Agriculture, Ecosystems and Environment.
• Keller, A. & Ankenbrand, M.J., 2021.Inferring core genome phylogenies for bacteria In A. Mengoni, M. Fondi, & G. Bacci, eds. Bacterial Pangenomics (in press). Heidelberg, Germany: Springer Verlag.
• Casanelles Abella, J., Müller, S., Keller, A., Aleixo, C., Alós Orti, M., Chiron, F., Deguines, N., Hallikma, T., Laanisto, L., Pinho, P., Samson, R., Tryjanowski, P., Van Mensel, A., Pellissier, L. & Moretti, M., 2021.How bees find a way in European cities: pollen metabarcoding unravels multiple feeding strategies and their effects on distribution patterns in four wild bee species. Journal of Applied Ecology, P. in press.
• Chui, S.X., Keller, A. & Leonhardt, S., 2021.Functional resin use in solitary bees. Ecological Entomology, P. in press.
• Piko, J., Keller, A., Geppert, C., Batáry, P., Tscharntke, T., Westphal, C. & Hass, A.L., 2021.Effects of three flower field types on bumblebees and their pollen diets. Basic and Applied Ecology, 52, Pp. 95–108. Available at: https://www.sciencedirect.com/science/article/pii/S143917912100027X.
• Tiede, J., Keller, A. & Eitzinger, B., 2021.DNA sequence-based biodiversity and interaction ecology. Basic and Applied Ecology.
• Mayr, A.V., Keller, A., Peters, M.K., Grimmer, G., Krischke, B., Geyer, M., Schmitt, T. & Steffan-Dewenter, I., 2021.Cryptic species and hidden ecological interactions of halictine bees along an elevational gradient. Ecology and Evolution. Available at: https://onlinelibrary.wiley.com/doi/abs/10.1002/ece3.7605.

  Abstract Changes of abiotic and biotic conditions along elevational gradients represent serious challenges to organisms which may promote the turnover of species, traits and biotic interaction partners. Here, we used molecular methods to study cuticular hydrocarbon (CHC) profiles, biotic interactions and phylogenetic relationships of halictid bees of the genus Lasioglossum along a 2,900 m elevational gradient at Mt. Kilimanjaro, Tanzania. We detected a strong species turnover of morphologically indistinguishable taxa with phylogenetically clustered cryptic species at high elevations, changes in CHC profiles, pollen resource diversity, and a turnover in the gut and body surface microbiome of bees. At high elevations, increased proportions of saturated compounds in CHC profiles indicate physiological adaptations to prevent desiccation. More specialized diets with higher proportions of low-quality Asteraceae pollen imply constraints in the availability of food resources. Interactive effects of climatic conditions on gut and surface microbiomes, CHC profiles, and pollen diet suggest complex feedbacks among abiotic conditions, ecological interactions, physiological adaptations, and phylogenetic constraints as drivers of halictid bee communities at Mt. Kilimanjaro.
• Hornick, T., Bastl, M., Bohlmann, S., Bonn, A., Bumberger, J., Dietrich, P., Gemeinholzer, B., Grote, R., Harpole, W.S., Heinold, B., Keller, A., Luttkus, M.L., Mäder, P., Motivans, E., Passonneau, S., Punyasena, S., Rakosy, D., Richter, A., Richter, R., Sickel, W., Steffan-Dewenter, I., Theodorou, P., Treudler, R., Werchan, B., Werchan, M., Wolke, R. & Dunker, S., 2021.An integrative environmental pollen diversity assessment and its importance for the Sustainable Development Goals. Plants, People, Planet, P. in press.
• Keller, A., McFrederick, Q.S., Dharampal, P., Steffan, S., Danforth, B.N. & Leonhardt, S.D., 2021.(More than) Hitchhikers through the network: The shared microbiome of bees and flowers. Current Opinion in Insect Science.

2020

• Khansaritoreh, E., Salamaki, Y., Ramezani, E., Akbari-Azirani, T., Keller, A., Neumann, K., Alizadeh, K., Zarre, S., Beckh, G. & Behling, H., 2020.Tracking beekeepers in floristic regions of Iran: employing DNA metabarcoding to determine the geographical origin of honey. Heliyon.
• Hifnawy, M.S., Fouda, M.M., Sayed, A.M., Mohammed, R., Hassan, H.M., AbouZid, S.F., Rateb, M.E., Keller, A., Adamek, M., Ziemert, N. & Abdelmohsen, U.R., 2020.The genus Micromonospora as a model microorganism for bioactive natural product discovery. Royal Society of Chemistry Advances, 10(35), Pp. 20939–20959. Available at: http://dx.doi.org/10.1039/D0RA04025H.

  This review covers the development of the genus Micromonospora as a model for natural product research and the timeline of discovery progress from the classical bioassay-guided approaches through the application of genome mining and genetic engineering techniques that target specific products. It focuses on the reported chemical structures along with their biological activities and the synthetic and biosynthetic studies they have inspired. This survey summarizes the extraordinary biosynthetic diversity that can emerge from a widely distributed actinomycete genus and supports future efforts to explore under-explored species in the search for novel natural products.
• Voulgari-Kokota, A., Steffan-Dewenter, I. & Keller, A., 2020.Susceptibility of red mason bee larvae to bacterial threats due to microbiome exchange with imported pollen provisions. Insects, 11(6). Available at: https://www.mdpi.com/2075-4450/11/6/373.

  Solitary bees are subject to a variety of pressures that cause severe population declines. Currently, habitat loss, temperature shifts, agrochemical exposure, and new parasites are identified as major threats. However, knowledge about detrimental bacteria is scarce, although they may disturb natural microbiomes, disturb nest environments, or harm the larvae directly. To address this gap, we investigated 12 Osmia bicornis nests with deceased larvae and 31 nests with healthy larvae from the same localities in a 16S ribosomal RNA (rRNA) gene metabarcoding study. We sampled larvae, pollen provisions, and nest material and then contrasted bacterial community composition and diversity in healthy and deceased nests. Microbiomes of pollen provisions and larvae showed similarities for healthy larvae, whilst this was not the case for deceased individuals. We identified three bacterial taxa assigned to Paenibacillus sp. (closely related to P. pabuli/amylolyticus/xylanexedens), Sporosarcina sp., and Bacillus sp. as indicative for bacterial communities of deceased larvae, as well as Lactobacillus for corresponding pollen provisions. Furthermore, we performed a provisioning experiment, where we fed larvae with untreated and sterilized pollens, as well as sterilized pollens inoculated with a Bacillus sp. isolate from a deceased larva. Untreated larval microbiomes were consistent with that of the pollen provided. Sterilized pollen alone did not lead to acute mortality, while no microbiome was recoverable from the larvae. In the inoculation treatment, we observed that larval microbiomes were dominated by the seeded bacterium, which resulted in enhanced mortality. These results support that larval microbiomes are strongly determined by the pollen provisions. Further, they underline the need for further investigation of the impact of detrimental bacterial acquired via pollens and potential buffering by a diverse pollen provision microbiome in solitary bees.
• Polidori, C., Jorge, A., Keller, A., Ornosa, C., Tormos, J., Asis, J.D. & Nieves-Aldrey, J.L., 2020.Strong phylogenetic constraint on transition metal incorporation in the mandibles of the hyper-diverse Hymenoptera (Insecta). Organisms, Diversity and Evolution, P. in press.
• Vaudo, A.D., Biddinger, D.J., Sickel, W., Keller, A. & López-Uribe, M.M., 2020.Introduced bees (Osmia cornifrons) collect pollen from both coevolved and novel host-plant species within their family-level phylogenetic preferences. Royal Society Open Science, P. in press.
• Trinkl, M., Kaluza, B.F., Wallace, H., Heard, T.A., Keller, A. & Leonhardt, S.D., 2020.Floral Species Richness Correlates with Changes in the Nutritional Quality of Larval Diets in a Stingless Bee. Insects, 11(2). Available at: https://www.mdpi.com/2075-4450/11/2/125.
• Degirmenci, L., Geiger, D., Rogé Ferreira, F.L., Keller, A., Krischke, B., Beye, M., Steffan-Dewenter, I. & Scheiner, R., 2020.CRISPR/Cas 9 mediated mutations as a new tool for studying taste in honeybees. Chemical Senses, P. bjaa063.
• Gaube, P., Junker, R.R. & Keller, A., 2020.Changes amid constancy: flower and leaf microbiomes along land use gradients and between bioregions. Basic and Applied Ecology, 50, Pp. 1–15. Available at: https://doi.org/10.1016%2Fj.baae.2020.10.003.
• Keller, A., Hohlfeld, S., Kolter, A., Schultz, J., Gemeinholzer, B. & Ankenbrand, M.J., 2020.BCdatabaser: on-the-fly reference database creation for DNA (meta-)barcoding. Bioinformatics, P. in press.

2019

• Sickel, W., Van der Weyer, A.-L., Bemm, F., Schultz, J. & Keller, A., 2019.Venus flytrap microbiota withstand harsh conditions during prey digestion. FEMS Microbiology Ecology, P. fiz010.
• Voulgari-Kokota, A., Ankenbrand, M., Grimmer, G., Steffan-Dewenter, I. & Keller, A., 2019.Linking the foraging patterns of megachilid bee species to nest bacteria. Ecology and Evolution, P. in press.
• Nürnberger, F., Keller, A., Härtel, S. & Steffan-Dewenter, I., 2019.Honey bee waggle dance communication increases diversity of pollen diets in intensively managed agricultural landscapes. Molecular Ecology, P. in press.
• Voulgari-Kokota, A., McFrederick, Q., Steffan-Dewenter, I. & Keller, A., 2019.Drivers, diversity and functions of solitary bee microbiota. Trends in Microbiology, P. in press.
• Villalobos, A.S., Wiese, J., Imhoff, J.F., Dorador, C., Keller, A. & Hentschel, U., 2019.Cold-adaptation of Subtercola vilae DB165T, an isolate from a high-altitude cold volcano lake, as revealed by its genome analysis.
• Peters, M.K., Hemp, A., Appelhans, T., Becker, J.N., Behler, C., Classen, A., Detsch, F., Ensslin, A., Ferger, S.W., Frederiksen, S.B., Gebert, F., Gerschlauer, F., Gütlein, A., Helbig-Bonitz, M., Hemp, C., Kindeketa, W.J., Kühnel, A., Mayr, A.V., Mwangomo, E., Ngereza, C., Njovu, H.K., Otte, I., Pabst, H., Renner, M., Röder, J., Rutten, G., Schellenberger Costa, D., Sierra-Cornejo, N., Vollstädt, M.G.R., Dulle, H.I., Eardley, C.D., Howell, K.M., Keller, A., Peters, R.S., Ssymank, A., Kakengi, V., Zhang, J., Bogner, C., Böhning-Gaese, K., Brandl, R., Hertel, D., Huwe, B., Kiese, R., Kleyer, M., Kuzyakov, Y., Nauss, T., Schleuning, M., Tschapka, M., Fischer, M. & Steffan-Dewenter, I., 2019.Climate–land-use interactions shape tropical mountain biodiversity and ecosystem functions. Nature. Available at: https://doi.org/10.1038/s41586-019-1048-z.

  Agriculture and the exploitation of natural resources have transformed tropical mountain ecosystems across the world, and the consequences of these transformations for biodiversity and ecosystem functioning are largely unknown1–3. Conclusions that are derived from studies in non-mountainous areas are not suitable for predicting the effects of land-use changes on tropical mountains because the climatic environment rapidly changes with elevation, which may mitigate or amplify the effects of land use4,5. It is of key importance to understand how the interplay of climate and land use constrains biodiversity and ecosystem functions to determine the consequences of global change for mountain ecosystems. Here we show that the interacting effects of climate and land use reshape elevational trends in biodiversity and ecosystem functions on Africa’s largest mountain, Mount Kilimanjaro (Tanzania). We find that increasing land-use intensity causes larger losses of plant and animal species richness in the arid lowlands than in humid submontane and montane zones. Increases in land-use intensity are associated with significant changes in the composition of plant, animal and microorganism communities; stronger modifications of plant and animal communities occur in arid and humid ecosystems, respectively. Temperature, precipitation and land use jointly modulate soil properties, nutrient turnover, greenhouse gas emissions, plant biomass and productivity, as well as animal interactions. Our data suggest that the response of ecosystem functions to land-use intensity depends strongly on climate; more-severe changes in ecosystem functioning occur in the arid lowlands and the cold montane zone. Interactions between climate and land use explained—on average—54\% of the variation in species richness, species composition and ecosystem functions, whereas only 30\% of variation was related to single drivers. Our study reveals that climate can modulate the effects of land use on biodiversity and ecosystem functioning, and points to a lowered resistance of ecosystems in climatically challenging environments to ongoing land-use changes in tropical mountainous regions.
• Voulgari-Kokota, A., Grimmer, G., Steffan-Dewenter, I. & Keller, A., 2019.Bacterial community structure and succession in nests of two megachilid bee genera. FEMS Microbiology Ecology, 95(1), P. fiy218. Available at: http://dx.doi.org/10.1093/femsec/fiy218.

2018

• Keller, A., Brandel, A., Becker, M.C., Balles, R., Abdelmohlsen, U.R., Ankenbrand, M.J. & Sickel, W., 2018.Wild bees and their nests host Paenibacillus bacteria with functional potential of avail. Microbiome, (6), P. 229.
• Bertolini, E., Kistenpfennig, C., Menegazzi, P., Keller, A., Koukidou, M. & Helfrich-F{ö}rster, C., 2018.The characterization of the circadian clock in the olive fly Bactrocera oleae (Diptera: Tephritidae) reveals a Drosophila-like organization. Scientific Reports, 8(1), P. 816. Available at: https://doi.org/10.1038/s41598-018-19255-8.
• Hafen, B., Wiesner, S., Schlegelmilch, K., Keller, A., Seefried, L., Ebert, R., Walles, H., Jakob, F. & Schütze, N., 2018.Physical contact between mesenchymal stem cells and endothelial precursors induces distinct signatures with relevance to the very early phase of regeneration. Journal of Cellular Biochemistry. Available at: https://onlinelibrary.wiley.com/doi/abs/10.1002/jcb.27175.

  Abstract Multipotent adult stem cells/precursor cells, especially of the mesenchymal and endothelial lineage, may have great potential for bone tissue engineering. Although their potential is highly recognized, not much is known about the underlying molecular mechanisms that initiate the regeneration process, connect osteogenesis, and angiogenesis and, finally, orchestrate renewal of bone tissue. Our study addressed these questions by generating two in vitro cell culture models to examine the changes in the global gene expression patterns of endothelial precursor cells and mesenchymal stem cells after 24 hours of either humoral (conditioned medium) or direct cell-cell interaction (co-culture). Endothelial precursor cells were isolated from human buffy coat and mesenchymal stem cells from the bone marrow of the femoral head. The comparison of the treated and control cells by microarray analyses revealed in total more than 1500 regulated genes, which were analyzed for their affiliation to angiogenesis and osteogenesis. Expression array analyses at the RNA and protein level revealed data with respect to regulated genes, pathways and targets that may represent a valid basis for further dissection of the systems biology of regeneration processes. It may also be helpful for the reconstitution of the natural composition of a regenerative microenvironment when targeting tissue regeneration both in vitro and in situ.
• Too, C.C., Keller, A., Sickel, W., Lee, S.M. & Yule, C.M., 2018.Microbial community structure in a Malaysian tropical peat swamp forest: the influence of tree species and depth. Frontiers in Microbiology, 9, P. 2859. Available at: https://www.frontiersin.org/article/10.3389/fmicb.2018.02859.

  Tropical peat swamp forests sequester globally significant stores of carbon in deep layers of waterlogged, anoxic, acidic and nutrient-depleted peat. The roles of microbes in supporting these forests through the formation of peat, carbon sequestration and nutrient cycling are virtually unknown. This study investigated physiochemical peat properties and microbial diversity between three dominant tree species: Shorea uliginosa (Dipterocarpaceae), Koompassia malaccensis (legumes associated with nitrogen-fixing bacteria), Eleiodoxa conferta (palm) and depths (surface, 45 cm, 90 cm) using microbial 16S rRNA gene amplicon sequencing. Water pH, oxygen, nitrogen, phosphorus, total phenolic contents and C/N ratio differed significantly between depths, but not tree species. Depth also strongly influenced microbial diversity and composition, while both depth and tree species exhibited significant impact on the archaeal communities. Microbial diversity was highest at the surface, where fresh leaf litter accumulates, and nutrient supply is guaranteed. Nitrogen was the core parameter correlating to microbial communities, but the interactive effects from various environmental variables displayed significant correlation to relative abundance of major microbial groups. Proteobacteria was the dominant phylum and the most abundant genus, Rhodoplanes, might be involved in nitrogen fixation. The most abundant methanogens and methanotrophs affiliated respectively to families Methanomassiliicoccaceae and Methylocystaceae. Our results demonstrated diverse microbial communities and provide valuable insights on microbial ecology in these extreme ecosystems.
• Ankenbrand, M.J., Hohlfeld, S.C.Y., Foerster, F. & Keller, A., 2018.FENNEC - Functional Exploration of Natural Networks and Ecological Communities. Methods in Ecology and Evolution, Pp. 2028–2033.

  Background: Assessment of species composition in ecological communities and networks is an important aspect of biodiversity research. Yet, for many ecological questions the ecological properties (traits) of organisms in a community are more informative than their scientific names. Furthermore, other properties like threat status, invasiveness, or human usage are relevant for many studies, but they can not be directly evaluated from taxonomic names alone. Despite the fact that various public databases collect such trait information, it is still a tedious manual task to enrich existing community tables with those traits, especially for large data sets. For example, nowadays, meta-barcoding or automatic image processing approaches are designed for high-throughput analyses, yielding thousands of taxa for hundreds of samples in very short time frames. Results: Here we present the FENNEC, a web-based workbench that eases this process by mapping publicly available trait data to the user{\textquoteright}s community tables in an automated process. We applied our novel approach to a case study in pollination ecology to demonstrate the usefulness of the FENNEC. The range of topics covered by the case study includes specialization, invasiveness, vulnerability, and agricultural relevance. Significance: The FENNEC is a free web-based tool that simplifies the inclusion of known species traits in ecological community analyses. We encourage scientists to participate in trait data submission to existing trait databases and to use the FENNEC for their analysis. A public instance containing various traits related to pollination ecology is available at http://fennec.molecular.eco
• Too, C.C., Ong, K.S., Ankenbrand, M.J., Lee, S.M., Yule, C.M. & Keller, A., 2018.Draft Genome Sequence of Paraburkholderia sp. Strain C35, Isolated from a Malaysian Tropical Peat Swamp Forest. Genome Announcements, 6(25). Available at: https://mra.asm.org/content/6/25/e00561-18.

  We report the draft genome sequence of a bacterial isolate, Paraburkholderia sp. strain C35, which was isolated from a Malaysian tropical peat swamp forest. The putative genes for the biogeochemical processes were annotated and are publicly available in the online databases.
• Too, C.C., Ong, K.S., Ankenbrand, M.J., Lee, S.M., Yule, C.M. & Keller, A., 2018.Draft Genome Sequence of Klebsiella sp. Strain C31 Isolated from a Malaysian Tropical Peat Swamp Forest. Genome announcements, 6(25), Pp. e00560–18.
• Too, C.C., Ong, K.S., Lee, S.M., Yule, C.M. & Keller, A., 2018.Draft Genome Sequence of Dyella sp. Strain C9, Isolated from a Malaysian Tropical Peat Swamp Forest. Microbiol Res Announc, 7(12), Pp. e01083–18.
• Too, C.C., Ong, K.S., Lee, S.M., Yule, C.M. & Keller, A., 2018.Draft Genome Sequence of Dyella sp. Strain C11, Isolated from a Malaysian Tropical Peat Swamp Forest. Genome announcements, 6(25), Pp. e00459–18.

2017

• Wurdack, M., Polidori, C., Keller, A., Feldhaar, H. & Schmitt, T., 2017.Release from prey preservation behavior via prey switch allowed diversification of cuticular hydrocarbon profiles in digger wasps. Evolution, in press.
• Danner, N., Keller, A., H{ä}rtel, S. & Steffan-Dewenter, I., 2017.Honey bee foraging ecology: Season but not landscape diversity shapes the amount and diversity of collected pollen. PloS one, 12(8), P. e0183716.
• Danner, N., Keller, A., Härtel, S. & Steffan-Dewenter, I., 2017.Honey bee foraging ecology: Season but not landscape diversity shapes the amount and diversity of collected pollen. PLoS one, in press.
• Kaluza, B.F., Wallace, H., Keller, A., Heard, T.A., Jeffers, B., Drescher, N., Blüthgen, N. & Leonhardt, S.D., 2017.Generalist social bees maximize diversity intake in plant species-rich and resource-abundant environments. Ecosphere, 8(3), P. e01758-n/a. Available at: http://dx.doi.org/10.1002/ecs2.1758.
• Ankenbrand, M.J., Hohlfeld, S., Hackl, T. & Förster, F., 2017.AliTV - interactive visualization of whole genome comparisons. PeerJ Comput. Sci., 3, P. e116. Available at: http://dblp.uni-trier.de/db/journals/peerj-cs/peerj-cs3.html#AnkenbrandHHF17.

2016

• Ankenbrand, M.J., Weber, L., Becker, D., Förster, F. & Bemm, F., 2016.TBro: visualization and management of de novo transcriptomes. Database, 2016.

  RNA sequencing (RNA-seq) has become a powerful tool to understand molecular mechanisms and/or developmental programs. It provides a fast, reliable and cost-effective method to access sets of expressed elements in a qualitative and quantitative manner. Especially for non-model organisms and in absence of a reference genome, RNA-seq data is used to reconstruct and quantify transcriptomes at the same time. Even SNPs, InDels, and alternative splicing events are predicted directly from the data without having a reference genome at hand. A key challenge, especially for non-computational personnal, is the management of the resulting datasets, consisting of different data types and formats. Here, we present TBro, a flexible de novo transcriptome browser, tackling this challenge. TBro aggregates sequences, their annotation, expression levels as well as differential testing results. It provides an easy-to-use interface to mine the aggregated data and generate publication-ready visualizations. Additionally, it supports users with an intuitive cart system, that helps collecting and analysing biological meaningful sets of transcripts. TBro’s modular architecture allows easy extension of its functionalities in the future. Especially, the integration of new data types such as proteomic quantifications or array-based gene expression data is straightforward. Thus, TBro is a fully featured yet flexible transcriptome browser that supports approaching complex biological questions and enhances collaboration of numerous researchers. Database URL: tbro.carnivorom.com
• Meuche, I., Keller, A., Ahmadsah, H., Ahmad, N. & Grafe, T.U., 2016.Silent listeners: Can preferences of eavesdropping midges predict the parasitism risk of their host?. Behavioral Ecology, 27, Pp. 995–1003.
• Bell, K., De Vere, N., Keller, A., Richardson, R., Gous, A., Burgess, K. & Brosi, B., 2016.Pollen DNA barcoding: current applications and future prospects. Genome, 59, Pp. 629–640.
• Becker, M. & Keller, A., 2016.Laboratory rearing of solitary bees and wasps. Insect Science, 23, P. 918.
• Horn, H., Keller, A., Hildebrandt, U., Kämpfer, P., Riederer, M. & Hentschel, U., 2016.Draft genome of the Arabidopsis thaliana phyllosphere bacterium, Williamsia sp. ARP1. Standards in Genomic Sciences.
• Keller, A., Grimmer, G., Sickel, W. & Ankenbrand, M.J., 2016.DNA-Metabarcoding – ein neuer Blick auf organismische Diversität. BioSpektrum, 22, Pp. 147–150.
• Faist, H., Keller, A., Hentschel, U. & Deeken, R., 2016.Crown galls of grapevine (Vitis vinifera) host distinct microbiota. Applied and Environmental Microbiology, 82, Pp. 5542–5552.
• Dotterweich, J., Schlegelmilch, K., Keller, A., Geyer, B., Schneider, D., Zeck, S., Tower, R.J., Ebert, R., Jakob, F. & Sch{ü}tze, N., 2016.Contact of myeloma cells induces a characteristic transcriptome signature in skeletal precursor cells--Implications for myeloma bone disease. Bone, 93, Pp. 155–166.
• Ankenbrand, M.J., Terhoeven, N., Hohlfeld, S., Förster, F. & Keller, A., 2016.biojs-io-biom, a {BioJS} component for handling data in Biological Observation Matrix ({BIOM}) format. F1000Research, 5, P. 2348. Available at: http://dx.doi.org/10.12688/f1000research.9618.1.
• Ankenbrand, M.J. & Keller, A., 2016.bcgTree: automatized phylogenetic tree building from bacterial core genomes. Genome, 59, Pp. 783–791.
• Sickel, W., Grafe, T.U., Meuche, I., Steffan-Dewenter, I. & Keller, A., 2016.Bacterial Diversity and Community Structure in Two Bornean Nepenthes Species with Differences in Nitrogen Acquisition Strategies. Microbial Ecology, 71, Pp. 938–953.

2015

• Zancolli, G., Mahsberg, D., Sickel, W. & Keller, A., 2015.Reptiles as reservoirs of bacterial infections: real threat or methodological bias?. Microbial Ecology, 70(3), Pp. 579–84.
• Fiala, B., Wells, K., Haubenreisser, J., Pittroff, A., Kaya-Zeeb, S., Chung, A.Y., bin Hashim, R. & Keller, A., 2015.Monophyletic clades of Macaranga pollinating thrips with high specificity to host plant taxonomic sections. Biological Journal of the Linnean Society, 116(3), Pp. 558–570.
• Junker, R.R. & Keller, A., 2015.Microhabitat heterogeneity across leaves and flower organs promotes bacterial diversity. FEMS Microbiology Ecology, 91(1), P. fiv09.

  Eukaryote-associated microbiomes interact with their hosts in multiple manners, thereby affecting the hosts' phenotype, physical condition and behaviour. In plants, bacteria have numerous functions, with variable net effects, both in natural and agricultural systems. However, information about the composition and diversity of the bacterial communities associated with different aboveground plant organs, particularly flowers, is lacking. In addition, the relative effects of microhabitat and environmental conditions on community establishment require further attention. Here, using culture-independent methods, we determine that leaves and three floral microhabitats (nectar, stamina and styles) of Metrosideros polymorpha (Myrtaceae), a tree endemic to Hawai'i, host unique indicator communities composed of relatively abundant bacterial taxa. These indicator communities are accompanied by a large number of ubiquitous or rare bacteria with lower abundances. In our study system, the strong effect of microhabitat filtering on plant-associated community composition and bacterial richness and diversity strongly exceeds the influence of environmental effects such as precipitation, altitude, substrate age and geographic distance. Thus, the bacterial richness of aboveground plant organs is strongly underestimated when only one microhabitat, e.g. leaves, is considered. Our study represents a first step towards a comprehensive characterization of the distribution, composition and underlying factors, of plant bacterial communities, with implications for future basic and applied research on plant health, pollination and reproduction.
• Ankenbrand, M.J., Keller, A., Wolf, M., Schultz, J. & Förster, F., 2015.ITS2 Database V: Twice as Much. Molecular Biology and Evolution, 32(11), Pp. 3030–3032. Available at: http://mbe.oxfordjournals.org/content/32/11/3030.abstract.

  The internal transcribed spacer 2 (ITS2) is a well-established marker for phylogenetic analyses in eukaryotes. A reliable resource for reference sequences and their secondary structures is the ITS2 database (http://its2.bioapps.biozentrum.uni-wuerzburg.de/). However, the database was last updated in 2011. Here, we present a major update of the underlying data almost doubling the number of entities. This increases the number of taxa represented within all major eukaryotic clades. Moreover, additional data has been added to underrepresented groups and some new groups have been added. The broader coverage across the tree of life improves phylogenetic analyses and the capability of ITS2 as a DNA barcode.
• Sickel, W., Ankenbrand, M., Grimmer, G., Holzschuh, A., Härtel, S., Lanzen, J., Steffan-Dewenter, I. & Keller, A., 2015.Increased efficiency in identifying mixed pollen samples by meta-barcoding with a dual-indexing approach. BMC Ecology, 15, P. 20.
• Junker, R.R., Blüthgen, N. & Keller, A., 2015.Functional and phylogenetic diversities of plant communities differently affect the structure of flower-visitor interactions and reveal convergences in floral traits. Evolutionary Ecology, 29, Pp. 437–450.
• Keller, A., Danner, N., Grimmer, G., Ankenbrand, M., {von der Ohe}, K., {von der Ohe}, W., Rost, S., Härtel, S. & Steffan-Dewenter, I., 2015.Evaluating multiplexed next-generation sequencing as a method in palynology for mixed pollen samples. Plant Biology, 17, Pp. 558–566.
• Wölfling, M., Rohrhirsch, M., Uhl, B. & Keller, A., 2015.DNA-analyses of Venerupis philippinarum (Adams and Reeve, 1850) with a new and constant shell-pattern from Italy, Emilia Romagna. Malacologia, 86(1), Pp. 30–32.

2014

• Keller, A., Härtel, S. & Steffan-Dewenter, I., 2014.Pollen DNA barcoding using next-generation sequencing. Barcode Bulletin, 5(3), P. 8.
• Rost, S., Bach, E., Neuner, C., Nanda, I., Dysek, S., Bittner, R.E., Keller, A., Bartsch, O., Mlynski, R. & Haaf, T., 2014.Novel form of X-linked nonsyndromic hearing loss with cochlear malformation caused by a mutation in the type IV collagen gene COL4A6. European Journal of Human Genetics, (22), Pp. 208–215.
• Schlegelmilch, K., Keller, A., Zehe, V., Hondke, S., Klein-Hitpass, L. & Schütze, N., 2014.Identification of WISP1 as an important survival factor in human mesenchymal stem cells. Gene, 551(2), Pp. 243–54.
• Junker, R.R., Romeike, T., Keller, A. & Langen, D., 2014.Density-dependent responses by bumblebees to flower dwelling bacteria. Apidologie, 45, Pp. 467–477.
• M{ü}ller, E., Keller, A., Fregin, A., M{ü}ller, C.R. & Rost, S., 2014.Confirmation of warfarin resistance of naturally occurring VKORC1 variants by coexpression with coagulation factor IX and in silico protein modelling. BMC Genetics, 15, P. 17.

2013

• Meuche, I., Brusa, O., Linsenmair, K.E., Keller, A. & Pr{ö}hl, H., 2013.Only distance matters--non-choosy females in a poison frog population. Frontiers in Zoology, 10(1), P. 29.
• Keller, A., Grimmer, G. & Steffan-Dewenter, I., 2013.Diverse microbiota identified in whole intact nest chambers of the red mason bee Osmia bicornis (Linnaeus 1758). PloS one, 8(10), P. e78296.

2012

• Ernst, R., Keller, A., Landburg, G., Grafe, T.U., Linsenmair, K.E., R{ö}del, M.-O. & Dziock, F., 2012.Common ancestry or environmental trait filters: cross-continental comparisons of trait--habitat relationships in tropical anuran amphibian assemblages. Global Ecology and Biogeography, 21(7), Pp. 704–715.

2011

• Buchheim, M.A., Keller, A., Koetschan, C., F{ö}rster, F., Merget, B. & Wolf, M., 2011.Internal transcribed spacer 2 (nu ITS2 rRNA) sequence-structure phylogenetics: towards an automated reconstruction of the green algal tree of life. PLoS One, 6(2), P. e16931.
• Junker, R.R., Daehler, C.C., D{ö}tterl, S., Keller, A. & Bl{ü}thgen, N., 2011.Hawaiian ant-flower networks: nectar-thieving ants prefer undefended native over introduced plants with floral defenses. Ecological Monographs, 81(2), Pp. 295–311.
• Junker, R.R., Loewel, C., Gross, R., D{ö}tterl, S., Keller, A. & Bl{ü}thgen, N., 2011.Composition of epiphytic bacterial communities differs on petals and leaves. Plant Biology, 13(6), Pp. 918–924.

2010

• Koetschan, C., F{ö}rster, F., Keller, A., Schleicher, T., Ruderisch, B., Schwarz, R., M{ü}ller, T., Wolf, M. & Schultz, J., 2010.The ITS2 Database III—sequences and structures for phylogeny. Nucleic Acids Research, 38(Suppl 1), Pp. D275-D279.
• Keller, A., Wolf, M. & Dandekar, T., 2010.Ribosomal RNA phylogenetics: the third dimension. Biologia, 65(3), Pp. 388–391.
• Hegewald, E., Wolf, M., Keller, A., Friedl, T. & Krienitz, L., 2010.ITS2 sequence-structure phylogeny in the Scenedesmaceae with special reference to \em Coelastrum \em (Chlorophyta, Chlorophyceae), including the new genera \em Comasiella \em and \em Pectinodesmus\em. Phycologia, 49(4), Pp. 325–335.
• Keller, A., F{ö}rster, F., M{ü}ller, T., Dandekar, T., Schultz, J., Wolf, M. & others, 2010.Including RNA secondary structures improves accuracy and robustness in reconstruction of phylogenetic trees. Biology Direct, 5, P. 4.

2009

• Keller, A., R{ö}del, M.-O., Linsenmair, K.E. & Grafe, T.U., 2009.The importance of environmental heterogeneity for species diversity and assemblage structure in Bornean stream frogs. Journal of Animal Ecology, 78(2), Pp. 305–314.
• Wiemers, M., Keller, A. & Wolf, M., 2009.ITS2 secondary structure improves phylogeny estimation in a radiation of blue butterflies of the subgenus \em Agrodiaetus \em (Lepidoptera: Lycaenidae: \em Polyommatus\em ). BMC Evolutionary Biology, 9(1), P. 300.
• Keller, A., 2009.Die Artenvielfalt der Amphibien in einem Tieflandregenwald auf Borneo. Terraria, 18(1), Pp. 80–83.
• Grafe, T.U. & Keller, A., 2009.A Bornean amphibian hotspot: the lowland mixed dipterocarp rainforest at Ulu Temburong National Park, Brunei Darussalam. Salamandra, 45, Pp. 16–25.
• Keller, A., Schleicher, T., Schultz, J., M{ü}ller, T., Dandekar, T. & Wolf, M., 2009.5.8S-28S rRNA interaction and HMM-based ITS2 annotation. Gene, 430(1), Pp. 50–57.

2008

• Keller, A., Schleicher, T., F{ö}rster, F., Ruderisch, B., Dandekar, T., M{ü}ller, T. & Wolf, M., 2008.ITS2 data corroborate a monophyletic chlorophycean DO-group (Sphaeropleales). BMC Evolutionary Biology, 8(1), P. 218. Available at: http://www.biomedcentral.com/1471-2148/8/218/.
• Keller, A., Siegle, M. & Grafe, T.U., 2008.Geographic distribution: Xenodermus javanicus (Short Note). Herpetological Review, 39, P. 373.
• Keller, A., Siegle, M. & Grafe, T.U., 2008.Geographic distribution: Parias sumatranus (Short Note). Herpetological Review, 39, P. 373.