Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2019
Authors
Synnøve Smebye Botnen Marie Louise Davey Anders Aas Tor Carlsen Ella Thoen Einar Heegaard Unni Vik Philipp Dresch Sunil Mundra Ursula Peintner Andy F. S. Taylor Håvard KauserudAbstract
Aim Polar and alpine ecosystems appear to be particularly sensitive to increasing temperatures and the altered precipitation patterns linked to climate change. However, little is currently known about how these environmental drivers may affect edaphic organisms within these ecosystems. In this study, we examined communities of plant root‐associated fungi (RAF) over large biogeographical scales and along climatic gradients in the North Atlantic region in order to gain insights into the potential effects of climate variability on these communities. We also investigated whether selected fungal traits were associated with particular climates. Locations Austria, Scotland, Mainland Norway, Iceland, Jan Mayen and Svalbard. Taxa Root fungi associated with the ectomycorrhizal and herbaceous plant Bistorta vivipara. Methods DNA metabarcoding of the ITS1 region was used to characterize the RAF of 302 whole plant root systems, which were analysed by means of ordination methods and linear modelling. Fungal spore length, width, volume and shape, as well as mycelial exploration type (ET) of ectomycorrhizal (ECM) basidiomycetes were summarized at a community level. Results The RAF communities exhibited strong biogeographical structuring, and both compositional variation as well as fungal species richness correlated with annual temperature and precipitation. In accordance with general island biogeography theory, the least species‐rich RAF communities were found on Jan Mayen, a remote and small island in the North Atlantic Ocean. Fungal spores tended to be more elongated with increasing latitude. We also observed a climate effect on which mycelial ET was dominating among the ectomycorrhizal fungi. Main conclusions Both geographical and environmental variables were important for shaping root‐associated fungal communities at a North Atlantic scale, including the High Arctic. Fungal OTU richness followed general biogeographical patterns and decreased with decreasing size and/or increasing isolation of the host plant population. The probability of possessing more elongated spores increases with latitude, which may be explained by a selection for greater dispersal capacity among more isolated host plant populations in the Arctic.
Abstract
The belowground environment is heterogeneous and complex at fine spatial scales. Physical structures, biotic components and abiotic conditions create a patchwork mosaic of potential niches for microbes. Questions remain about mechanisms and patterns of community assembly belowground, including: Do fungal and bacterial communities assemble differently? How do microbes reach the roots of host plants? Within a 4 m2 plot in alpine vegetation, high throughput sequencing of the 16S (bacteria) and ITS1 (fungal) ribosomal RNA genes was used to characterise microbial community composition in roots and adjacent soil of a viviparous host plant (Bistorta vivipara). At fine spatial scales, beta-diversity patterns in belowground bacterial and fungal communities were consistent, although compositional change was greater in bacteria than fungi. Spatial structure and distance-decay relationships were also similar for bacteria and fungi, with significant spatial structure detected at <50 cm among root- but not soil-associated microbes. Recruitment of root microbes from the soil community appeared limited at this sampling and sequencing depth. Possible explanations for this include recruitment from low-abundance populations of soil microbes, active recruitment from neighbouring plants and/or vertical transmission of symbionts to new clones, suggesting varied methods of microbial community assembly for viviparous plants. Our results suggest that even at relatively small spatial scales, deterministic processes play a significant role in belowground microbial community structure and assembly.
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Authors
Trygve S. Aamlid Tatsiana Espevig Pia Heltoft Oiva Niemeläinen P. Ruttunnen A. Kedonpara d Widmark Tom Hsiang Annick BertrandAbstract
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Abstract
Interspecific brood parasitism is common in many animal systems. Brood parasites enter the nests of other species and divert host resources for producing their own offspring, which can lead to strong antagonistic parasite–host coevolution. Here, we look at commonalities among social insect species that are victims of brood parasites, and use phylogenetic data and information on geographical range size to predict which species are most probably to fall victims to brood parasites in the future. In our analyses, we focus on three eusocial hymenopteran groups and their brood parasites: (i) bumblebees, (ii) Myrmica ants, and (iii) vespine and polistine wasps. In these groups, some, but not all, species are parasitized by obligate workerless inquilines that only produce reproductive-caste descendants.We find phylogenetic signals for geographical range size and the presence of parasites in bumblebees, but not in ants and wasps. Phylogenetic logistic regressions indicate that the probability of being attacked by one or more brood parasite species increases with the size of the geographical range in bumblebees, but the effect is statistically only marginally significant in ants. However, non-phylogenetic logistic regressions suggest that bumblebee species with the largest geographical range sizes may have a lower likelihood of harbouring social parasites than do hosts with medium-sized ranges. Our results provide new insights into the ecology and evolution of host–social parasite systems, and indicate that host phylogeny and geographical range size can be used to predict threats posed by social parasites, as well to design efficient conservation measures for both hosts and their parasites. This article is part of the theme issue ‘The coevolutionary biology of brood parasitism: from mechanism to pattern’.
Authors
Tommi Nyman Renske E Onstein Daniele Silvestro Saskia Wutke Andreas Taeger Niklas Wahlberg Stephan Martin Blank Tobias MalmAbstract
The insect order Hymenoptera originated during the Permian nearly 300 Mya. Ancestrally herbivorous hymenopteran lineages today make up the paraphyletic suborder ‘Symphyta’, which encompasses c. 8200 species with very diverse host-plant associations. We use phylogeny-based statistical analyses to explore the drivers of diversity dynamics within the ‘Symphyta’, with a particular focus on the hypothesis that diversification of herbivorous insects has been driven by the explosive radiation of angiosperms during and after the Cretaceous. Our ancestral-state estimates reveal that the first symphytans fed on gymnosperms, and that shifts onto angiosperms and pteridophytes – and back – have occurred at different time intervals in different groups. Trait-dependent analyses indicate that average net diversification rates do not differ between symphytan lineages feeding on angiosperms, gymnosperms or pteridophytes, but trait-independent models show that the highest diversification rates are found in a few angiosperm-feeding lineages that may have been favoured by the radiations of their host taxa during the Cenozoic. Intriguingly, lineages-through-time plots show signs of an early Cretaceous mass extinction, with a recovery starting first in angiosperm-associated clades. Hence, the oft-invoked assumption of herbivore diversification driven by the rise of flowering plants may overlook a Cretaceous global turnover in insect herbivore communities during the rapid displacement of gymnosperm- and pteridophyte-dominated floras by angiosperms.
Authors
Robert BarneveldAbstract
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Authors
Mehreteab TesfaiAbstract
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Abstract
Legume-based cropping system and Brachiaria forage system could play a significant role in enhancing food and nutrition security and sustainable intensifications of African agriculture. To reveal this potential, a comprehensive review of literatures and assessment was performed using key indicators in relation to food and nutrition quality, agro-ecological services and socioeconomic benefits. The key indicators for legumes intercropping systems include: Grain yield, soil organic matter, food availability, nutritive values of legumes, maize and millets- based foods, proportion of income from crop sale and percentage of farmers aware and/or adopting intercropping. In the case of Brachiaria system, the forage biomass, milk yield, availability of milk, milk nutrition contents, income from Brachiaria grass and milk sale and people practising the Brachiaria technology were considered key indicators. Both systems showed positive impacts and contribute to a range of the United Nation’s sustainable development goals including 1, 2, 3, 12, 13 and 15 and other associated targets. Integrating legume-based cropping systems and Brachiaria forage system will enhance contributions of smallholder farmers to food and nutrition security. The necessary changes needed in technology, institutions and policies to upscale legume-based cropping systems and Brachiaria forage system were suggested. These changes include improved varieties, quality seeds, improved cultivation practices, market provision, effective extension and advisory services and support to the seed productions and distribution systems, among others. Yet, to fully tap the potentials of legume-based and Brachiaria forage systems sustainably and raise the profile of these climate smart systems, context specific research measures are necessary.