| 1. |
- Blanchet, F. Guillaume, et al.
(författare)
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Related herbivore species show similar temporal dynamics
- 2018
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Ingår i: Journal of Animal Ecology. - : Wiley. - 0021-8790 .- 1365-2656. ; 87:3, s. 801-812
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Tidskriftsartikel (refereegranskat)abstract
- 1. Within natural communities, different taxa display different dynamics in time. Why this is the case we do not fully know. This thwarts our ability to predict changes in community structure, which is important for both the conservation of rare species in natural communities and for the prediction of pest outbreaks in agriculture. 2. Species sharing phylogeny, natural enemies and/or life-history traits have been hypothesized to share similar temporal dynamics. We operationalized these concepts into testing whether feeding guild, voltinism, similarity in parasitoid community and/or phylogenetic relatedness explained similarities in temporal dynamics among herbivorous community members. 3. Focusing on two similar datasets from different geographical regions (Finland and Japan), we used asymmetric eigenvector maps as temporal variables to characterize species-and community-level dynamics of specialist insect herbivores on oak (Quercus). We then assessed whether feeding guild, voltinism, similarity in parasitoid community and/or phylogenetic relatedness explained similarities in temporal dynamics among taxa. 4. Species-specific temporal dynamics varied widely, ranging from directional decline or increase to more complex patterns. Phylogeny was a clear predictor of similarity in temporal dynamics at the Finnish site, whereas for the Japanese site, the data were uninformative regarding a phylogenetic imprint. Voltinism, feeding guild and parasitoid overlap explained little variation at either location. Despite the rapid temporal dynamics observed at the level of individual species, these changes did not translate into any consistent temporal changes at the community level in either Finland or Japan. 5. Overall, our findings offer no direct support for the notion that species sharing natural enemies and/or life-history traits would be characterized by similar temporal dynamics, but reveal a strong imprint of phylogenetic relatedness. As this phylogenetic signal cannot be attributed to guild, voltinism or parasitoids, it will likely derive from shared microhabitat, microclimate, anatomy, physiology or behaviour. This has important implications for predicting insect outbreaks and for informing insect conservation. We hope that future studies will assess the generality of our findings across plant-feeding insect communities and beyond, and establish the more precise mechanism(s) underlying the phylogenetic imprint.
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| 2. |
- Cirtwill, Alyssa R., et al.
(författare)
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Flower-visitor and pollen-load data provide complementary insight into species and individual network roles
- 2024
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Ingår i: Oikos. - : John Wiley & Sons. - 0030-1299 .- 1600-0706. ; :4
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Tidskriftsartikel (refereegranskat)abstract
- Most animal pollination results from plant–insect interactions, but how we perceive these interactions may differ with the sampling method adopted. The two most common methods are observations of visits by pollinators to plants and observations of pollen loads carried by insects. Each method could favour the detection of different species and interactions, and pollen load observations typically reveal more interactions per individual insect than visit observations. Moreover, while observations concern plant and insect individuals, networks are frequently analysed at the level of species. Although networks constructed using visitation and pollen-load data have occasionally been compared in relatively specialised, bee-dominated systems, it is not known how sampling methodology will affect our perception of how species (and individuals within species) interact in a more generalist system. Here we use a Diptera-dominated high-Arctic plant–insect community to explore how sampling approach shapes several measures of species' interactions (focusing on specialisation), and what we can learn about how the interactions of individuals relate to those of species. We found that species degrees, interaction strengths, and species motif roles were significantly correlated across the two method-specific versions of the network. However, absolute differences in degrees and motif roles were greater than could be explained by the greater number of interactions per individual provided by the pollen-load data. Thus, despite the correlations between species roles in networks built using visitation and pollen-load data, we infer that these two perspectives yield fundamentally different summaries of the ways species fit into their communities. Further, individuals' roles generally predicted the species' overall role, but high variability among individuals means that species' roles cannot be used to predict those of particular individuals. These findings emphasize the importance of adopting a dual perspective on bipartite networks, as based on the different information inherent in insect visits and pollen loads.
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| 3. |
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| 4. |
- Jeppsson, Tobias, et al.
(författare)
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Oh, how we pick and choose: on theoretical constructs in subfields of ecology
- 2016
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Ecology consists of a large number of theoretical constructs, empirical patterns and methods; a pool from which applied ecology can draw ideas when exploring practical problems. Subfields of applied ecology - including pest control, conservation, and wildlife management - deal with the management of biological populations, and should therefore rest on the same ecological foundations. But is this really the case? We study this issue by analyzing recent citation rates (2010-2014) to more than 130 highly cited, classic publications, covering a wide range of topics. Using ordination methods, we find a clear clustering of journals, where conservation occupies another part of the ordination space than pest control. Classifying papers into broad topics reveals that the ordination patterns are driven by striking differences in how often ecological concepts are used in different subfields. While some patterns are easy to understand, e.g. the use of biodiversity concepts in conservation, others are left unexplained. For instance, the lack of spatial concepts and competition in pest control, predation in conservation journals, and foodweb ideas in wildlife journals are harder to understand. Microbial ecology also appears devoid of large parts of ecological theory. These patterns imply distinct divides within ecology, where subfields selectively use certain parts of ecological theory. Therefore, we argue that work in applied ecology would benefit from broader theoretical perspectives. Collaboration and inspiration across sub-disciplines could be one way to achieve this, perhaps inspiring novel research directions.
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| 5. |
- Jonsson, Mattias, et al.
(författare)
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Relationships between natural enemy diversity and biological control
- 2017
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Ingår i: Current Opinion in Insect Science. - : Elsevier BV. - 2214-5745 .- 2214-5753. ; 20, s. 1-6
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Tidskriftsartikel (refereegranskat)abstract
- Natural enemy diversity generally strengthens biological control, but individual studies have found everything from positive to negative effects. We discuss the factors that promote these different outcomes. We argue that a trait-based approach is helpful to improve our understanding of the relationship between enemy diversity and biological control, and suggest that enemy diversity is likely to be particularly important as an insurance against effects of climate change. Future research should increase the scale and ecological realism of enemy diversity studies, and consider both the strength and stability of biological control. Such research is likely to reveal even stronger evidence that conserving enemy biodiversity will improve biological pest control.
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| 6. |
- Jonsson, Tomas, et al.
(författare)
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Predictive power of food web models based on body size decreases with trophic complexity
- 2018
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Ingår i: Ecology Letters. - : Wiley-Blackwell Publishing Inc.. - 1461-023X .- 1461-0248. ; 21:5, s. 702-712
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Tidskriftsartikel (refereegranskat)abstract
- Food web models parameterised using body size show promise to predict trophic interaction strengths (IS) and abundance dynamics. However, this remains to be rigorously tested in food webs beyond simple trophic modules, where indirect and intraguild interactions could be important and driven by traits other than body size. We systematically varied predator body size, guild composition and richness in microcosm insect webs and compared experimental outcomes with predictions of IS from models with allometrically scaled parameters. Body size was a strong predictor of IS in simple modules (r(2)=0.92), but with increasing complexity the predictive power decreased, with model IS being consistently overestimated. We quantify the strength of observed trophic interaction modifications, partition this into density-mediated vs. behaviour-mediated indirect effects and show that model shortcomings in predicting IS is related to the size of behaviour-mediated effects. Our findings encourage development of dynamical food web models explicitly including and exploring indirect mechanisms.
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| 7. |
- Kaartinen, Riikka, et al.
(författare)
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A rapid assessment of a poorly known insect group
- 2016
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Ingår i: Insect Conservation and Diversity. - : Wiley. - 1752-458X .- 1752-4598. ; 9, s. 49-62
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Tidskriftsartikel (refereegranskat)abstract
- 1. 'Conservation planning and ecological analyses require large-scale data on species' abundance and distribution. We describe a national effort to quickly establish the distributions of taxa with hard-to-identify adults but easily identifiable larval stages: cynipid gall wasps (Hymenoptera: Cynipidae, Cynipini) on oak (Quercus robur).2. The survey was implemented by volunteers across 239 sites over 687 km of latitude. It yielded 10 523 galls, which were identified by specialists. The material revealed two species new to Finland and the national distributions and local abundances of 16 species.3. The likelihood of finding a given species was significantly affected by the visual apparency of its galls. This suggests that some cryptic generations may have been missed in the sampling.4. At the national level, our study exposed systematic changes in the species richness of insect taxa associated with a patchily distributed host plant towards its range margin. Species' incidences decline as host trees grow increasingly scattered within the landscape.5. From a conservation perspective, the data increased eight-fold the known records of gall wasps from Finland, and informed the first assessment of national threat status of these taxa.6. Our study reveals how the efforts of the public may be efficiently harnessed for revealing the current status of poorly known taxa. In addition to delivering a first survey of the target taxa, and of factors affecting their distribution, such 'citizen science' may generate a permanent base of enthusiasts for the future monitoring of changes and trends.
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| 8. |
- Kaartinen, Riikka, et al.
(författare)
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Establishing a community-wide DNA barcode library as a new tool for arctic research
- 2016
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Ingår i: Molecular Ecology Resources. - : Wiley. - 1755-098X .- 1755-0998. ; 16, s. 809-822
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Tidskriftsartikel (refereegranskat)abstract
- DNA sequences offer powerful tools for describing the members and interactions of natural communities. In this study, we establish the to-date most comprehensive library of DNA barcodes for a terrestrial site, including all known macroscopic animals and vascular plants of an intensively studied area of the High Arctic, the Zackenberg Valley in Northeast Greenland. To demonstrate its utility, we apply the library to identify nearly 20 000 arthropod individuals from two Malaise traps, each operated for two summers. Drawing on this material, we estimate the coverage of previous morphology-based species inventories, derive a snapshot of faunal turnover in space and time and describe the abundance and phenology of species in the rapidly changing arctic environment. Overall, 403 terrestrial animal and 160 vascular plant species were recorded by morphology-based techniques. DNA barcodes (CO1) offered high resolution in discriminating among the local animal taxa, with 92% of morphologically distinguishable taxa assigned to unique Barcode Index Numbers (BINs) and 93% to monophyletic clusters. For vascular plants, resolution was lower, with 54% of species forming monophyletic clusters based on barcode regions rbcLa and ITS2. Malaise catches revealed 122 BINs not detected by previous sampling and DNA barcoding. The insect community was dominated by a few highly abundant taxa. Even closely related taxa differed in phenology, emphasizing the need for species-level resolution when describing ongoing shifts in arctic communities and ecosystems. The DNA barcode library now established for Zackenberg offers new scope for such explorations, and for the detailed dissection of interspecific interactions throughout the community.
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| 9. |
- Kaartinen, Riikka, et al.
(författare)
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Shade trees decrease pest abundances on brassica crops in Kenya
- 2019
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Ingår i: Agroforestry Systems. - : Springer Science and Business Media LLC. - 0167-4366 .- 1572-9680. ; 93, s. 641-652
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Tidskriftsartikel (refereegranskat)abstract
- Agroforestry practices may mitigate the current loss of biodiversity and ecosystem services due to deforestation and agricultural intensification. To examine the effects of agroforestry on the ecosystem service of pest regulation, we assessed pest abundances and biological control potential in shaded and open kale (Brassica oleracea L. acephala) fields in Western Kenya. Specifically, we compared the abundance of pest aphids and caterpillars, ground-dwelling ants, spiders and predatory beetles, and examined aphid parasitism rates, predation rates on diamondback moth eggs, attack rates on surrogate caterpillars and bird predation on aphids. Shade trees effectively reduced abundances of aphids, caterpillars and increased abundances of spiders and predatory beetles, but neither affected ant abundances, or predation and parasitism rates. Our results suggest that presence of shade trees can decrease pest abundances, but that this is not only due to improved biological control by natural enemies but also due to microclimatic conditions affecting pest performance and bottom-up processes such as changes in plant quality and soil conditions. We encourage studies exploring simultaneously how top-down and bottom-up processes affect pest regulation in agroforestry settings.
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| 10. |
- Kaartinen, Riikka, et al.
(författare)
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Species’ roles in food webs show fidelity across a highly variable oak forest
- 2015
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Ingår i: Ecography. - : Wiley. - 0906-7590 .- 1600-0587. ; 38, s. 130-139
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Tidskriftsartikel (refereegranskat)abstract
- Ecological communities are composed of many species and an intricate network of interactions between them. Because of their overall complexity, an intriguing approach to understanding network structure is by breaking it down into the structural roles of its constituent species. The structural role of a species can be directly measured based on how it appears in network motifs - the basic building blocks of complex networks. Here, we study the distribution of species' roles at three distinct spatio-temporal scales (i.e. species, network, and temporal) in host-parasitoid networks collected across 22 sites over two years within a fragmented landscape of oaks in southern Finland. We found that species' roles for hosts and parasitoids were heterogeneously distributed across the study system but that roles are strongly conserved over spatial scales. In addition, we found that species' roles were remarkably consistent between years even in the presence of disturbances (e.g. species turnover). Overall, our results suggest that species' roles are an intrinsic property of species that may be predictable over spatial and temporal scales.
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