| 1. |
- Gaertner, Mirijam, et al.
(författare)
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Invasive plants as drivers of regime shifts : identifying high-priority invaders that alter feedback relationships
- 2014
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Ingår i: Diversity & distributions. - : Wiley. - 1366-9516 .- 1472-4642. ; 20:7, s. 733-744
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Forskningsöversikt (refereegranskat)abstract
- Aim A major challenge for invasion ecology is to identify high-impact invaders to guide prioritization of management interventions. We argue that species with the potential to cause regime shifts (altered states of ecosystem structure and function that are difficult or impossible to reverse) should be prioritized. These are species that modify ecosystems in ways that enhance their own persistence and suppress that of native species through reinforcing feedback processes. Methods Using both systems analysis and meta-analysis approaches, we synthesized changes to ecosystems caused by 173 invasive plant species. For the systems analysis, we examined published studies of impacts of invasive plants to determine which presented evidence consistent with a reinforcement of feedback processes. For the meta-analysis, we calculated the effect size ratio between standardized changes in recipient ecosystem and in the status of introduced species as an indication of a reinforcing feedback in particular species-environment combinations. The systems analysis approach allowed us to conceptualize regime shifts in invader-dominated landscapes and to estimate the likelihood of such changes occurring. The meta-analysis allowed us to quantitatively verify the conceptual model and the key invader-context feedbacks and to detect the strength and direction of feedbacks. Results Most reinforcing feedbacks involve impacts on soil-nutrient cycling by shrub and tree invaders in forests and herbaceous invaders in wetlands. Feedbacks resulting in regime shifts were most likely related to processes associated with seed banks, fire and nutrient cycling. Results were used to derive a key for identifying high-impact invaders. Main conclusions Identifying combinations of plant life-forms and ecosystems most likely to result in regime shifts is a robust approach for predicting high-impact invasions and therefore for prioritizing management interventions. The meta-analysis revealed the need for more quantitative studies, including manipulative experiments, on ecosystem feedbacks.
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| 2. |
- Landi, Pietro, et al.
(författare)
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Complexity and stability of adaptive ecological networks : a survey of the theory in community ecology
- 2018
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Ingår i: Systems analysis approach for complex global challenges. - Cham : Springer. - 9783319714868 - 9783319714851 ; , s. 209-248
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Bokkapitel (refereegranskat)abstract
- Background and Significance of the topic: The planet is changing at paces never observed before. Species extinction is happening at faster rates than ever, greatly exceeding the five mass extinctions in the fossil record. Nevertheless, human life is strongly based on services provided by ecosystems, thus the responses to global change of the planet's natural heritage are of immediate concern. Understanding the relationship between complexity and stability of ecosystems is of key importance for the maintenance of the balance of human growth and the conservation of all the natural services that ecosystems provide.Methodology: The concept of ecological networks and their characteristics are first introduced, followed by central and occasionally contrasting definitions of complexity and stability. The literature on the relationship between complexity and stability in different types of models and few real ecosystems is then reviewed, highlighting the theoretical debate and the lack of consensual agreement.Application/Relevance to systems analysis: This chapter uses ecological-network models to study the relationship between complexity and stability of natural ecosystems.Policy and/or practice implications: Mathematical network models can be used to simplify the vast complexity of the real world, to formally describe and investigate ecological phenomena, and to understand ecosystems propensity of returning to its functioning regime after a stress or a perturbation.Discussion and conclusion: The chapter concludes by summarising the importance of this line of research for the successful management and conservation of biodiversity and ecosystem services.
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| 3. |
- Landi, Pietro, et al.
(författare)
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Complexity and stability of ecological networks : a review of the theory
- 2018
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Ingår i: Population Ecology. - : Springer. - 1438-3896 .- 1438-390X. ; 60:4, s. 319-345
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Forskningsöversikt (refereegranskat)abstract
- Our planet is changing at paces never observed before. Species extinction is happening at faster rates than ever, greatly exceeding the five mass extinctions in the fossil record. Nevertheless, our lives are strongly based on services provided by ecosystems, thus the responses to global change of our natural heritage are of immediate concern. Understanding the relationship between complexity and stability of ecosystems is of key importance for the maintenance of the balance of human growth and the conservation of all the natural services that ecosystems provide. Mathematical network models can be used to simplify the vast complexity of the real world, to formally describe and investigate ecological phenomena, and to understand ecosystems propensity of returning to its functioning regime after a stress or a perturbation. The use of ecological-network models to study the relationship between complexity and stability of natural ecosystems is the focus of this review. The concept of ecological networks and their characteristics are first introduced, followed by central and occasionally contrasting definitions of complexity and stability. The literature on the relationship between complexity and stability in different types of models and in real ecosystems is then reviewed, highlighting the theoretical debate and the lack of consensual agreement. The summary of the importance of this line of research for the successful management and conservation of biodiversity and ecosystem services concludes the review.
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| 4. |
- Liu, Haoqi, et al.
(författare)
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How species characteristics affect extinction through habitat loss
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- With an increasing number of species at risk of extinction because of habitat loss, and extinction risks varying across species with different characteristics, it becomes essential to understand which and how species with different characteristics respond to habitat loss so as to prevent species loss. Although there exists a substantive literature on this subject, studies have so far not taken into account that natural communities have been formed through evolution, and that habitat loss is both heterogeneous in space and dynamic in time. Here, we design a spatially explicit evolving food-web model and expose the evolved communities to both random and spatially contagious habitat loss. We show that: (1) species that are large, rare, at high trophic levels, with small biomass energy intake, or having small spatial distribution differences with the autotrophic species are particularly susceptible to habitat loss. (2) Large species or species at high trophic level are more vulnerable to random habitat loss, while small species or species at low trophic levels are more vulnerable to contagious habitat loss. (3) Food webs are less robust for random habitat loss than for contagious habitat loss. (4) Reduction of body sizes is warning signal for food-web collapse. Taken together, these results facilitate identifying the most vulnerable species and the most damaging kinds of habitat loss.
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| 5. |
- Rodger, James G., et al.
(författare)
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Widespread vulnerability of flowering plant seed production to pollinator declines
- 2021
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Ingår i: Science Advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 7:42
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Tidskriftsartikel (refereegranskat)abstract
- Despite evidence of pollinator declines from many regions across the globe, the threat this poses to plant populations is not clear because plants can often produce seeds without animal pollinators. Here, we quantify pollinator contribution to seed production by comparing fertility in the presence versus the absence of pollinators for a global dataset of 1174 plant species. We estimate that, without pollinators, a third of flowering plant species would produce no seeds and half would suffer an 80% or more reduction in fertility. Pollinator contribution to plant reproduction is higher in plants with tree growth form, multiple reproductive episodes, more specialized pollination systems, and tropical distributions, making these groups especially vulnerable to reduced service from pollinators. These results suggest that, without mitigating efforts, pollinator declines have the potential to reduce reproduction for most plant species, increasing the risk of population declines.
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| 6. |
- Rossberg, Axel G., et al.
(författare)
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Lets Train More Theoretical Ecologists - Here Is Why
- 2019
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Ingår i: Trends in Ecology & Evolution. - : ELSEVIER SCIENCE LONDON. - 0169-5347 .- 1872-8383. ; 34:9, s. 759-762
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- A tangled web of vicious circles, driven by cultural issues, has prevented ecology from growing strong theoretical roots. Now this hinders development of effective conservation policies. To overcome these barriers in view of urgent societal needs, we propose a global network of postgraduate theoretical training programs.
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| 7. |
- Wickman, Jonas, et al.
(författare)
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How geographic productivity patterns affect food-web evolution
- 2020
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Ingår i: Journal of Theoretical Biology. - : Elsevier. - 0022-5193 .- 1095-8541. ; 506
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Tidskriftsartikel (refereegranskat)abstract
- It is well recognized that spatial heterogeneity and overall productivity have important consequences for the diversity and community structure of food webs. Yet, few, if any, studies have considered the effects of heterogeneous spatial distributions of primary production. Here, we theoretically investigate how the variance and autocorrelation length of primary production affect properties of evolved food webs consisting of one autotroph and several heterotrophs. We report the following findings. (1) Diversity increases with landscape variance and is unimodal in autocorrelation length. (2) Trophic level increases with high landscape variance and is unimodal in autocorrelation length. (3) The extent to which the spatial distribution of heterotrophs differ from that of the autotroph increases with variance and decreases with autocorrelation length. (4) Components of initial disruptive selection experienced by the ancestral heterotroph predict properties of the final evolved communities. Prior to our study reported here, several authors had hypothesized that diversity increases with the variance of productivity. Our results support their hypothesis and contributes new facets by providing quantitative predictions that also account for autocorrelation length and additional properties of the evolved communities.
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| 8. |
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| 9. |
- Zhang, Jin-Yan, et al.
(författare)
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Dimethylsulfoxide-soluble Smoking Particles and Nicotine Affect Vascular Contractibility
- 2009
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Ingår i: Archives of Pharmacal Research. - : Springer Science and Business Media LLC. - 1976-3786 .- 0253-6269. ; 32:10, s. 1475-1481
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Tidskriftsartikel (refereegranskat)abstract
- The aim is to study the effect of dimethylsulfoxide-soluble smoking particles (DSP) and nicotine on the contractility of rat mesenteric artery. The superior mesenteric artery segments were cultured with DSP or nicotine for 24 h. The vascular contractibility was recorded with myograph system. DSP 0.4 mL/L and nicotine 0.48 and 0.96 mg/L shifted the concentration-contractile curves induced by sarafotoxin 6c, a selective agonist for ETB receptor toward the left with increased E-max. DSP 0.4 mL/L and nicotine 0.96 mg/L shifted ETA receptor-mediated the concentration-contractile curves toward the left with increased E-max. However, nicotine 0.06 mg/L which is the equivalent concentration of nicotine in DSP 0.4 mL/L did not affect the curves and the E-max mediated with ETA receptor and ETB receptor. DSP 0.2 and 0.4 mL/L shifted the concentration-contractile curves induced by noradrenaline toward the right with decreased E-max. Neither did nicotine 0.06 and 0.96 mg/L. Both DSP and nicotine shifted the concentration-contractile curves induced by 5-hydroxytryptamine (5-HT) toward the right parallely. DSP changed the phenotypes towards an increased efficacy of ETA receptor and ETB receptor, and a reduced efficacy of 5-HT receptor and alpha-adrenocceptor. The effects of DSP on ETB receptor, ETA receptor and alpha-adrenocceptor were independent of nicotine. The effect on 5-HT receptor was responsible to nicotine.
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| 10. |
- Zhang, Wei, et al.
(författare)
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Activation of nuclear factor-kappa B pathway is responsible for tumor necrosis factor-a-induced up-regulation of endothelin B2 receptor expression in vascular smooth muscle cells in vitro
- 2012
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Ingår i: Toxicology Letters. - : Elsevier BV. - 1879-3169 .- 0378-4274. ; 209:2, s. 107-112
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Tidskriftsartikel (refereegranskat)abstract
- The endothelin B2 (ETB2) receptors are induced in vascular smooth muscle cells (VSMCs) in cardiovascular diseases. We tested if in vitro short-term exposure to the pro-inflammatory cytokine tumor necrosis factor-alpha (TNF-alpha) could up-regulate ETB2 receptors in rat mesenteric arteries, and if this effect is through activation of intracellular nuclear factor-kappa B (NF-kappa B) pathway. The mesenteric arteries were dissected from male Sprague-Dawley rats and the endothelium was removed. The arteries were co-incubated with TNF-alpha in serum-free Dulbecco's modified Eagle's medium. Real-time reverse transcription-PCR, Western blot and immunohistochemical staining were employed to assess the mRNA/protein expression of ETB2 receptors and activation of NF-kappa B pathway. The results showed that, during organ culture. TNF-alpha concentration-dependently enhanced ET52 receptors expression at both mRNA and protein levels, paralleled with activation of NF-kappa B pathway in VSMC. The up-regulated ETB2 receptor expression and NF-kappa B activation could be effectively suppressed by general transcriptional inhibitor actinomycin D, or either of the selective I kappa B kinase inhibitors wedelolactone and IMD-0354. Conclusively, the activation of intracellular NF-kappa B pathway is responsible for the up-regulation of ETB2 receptors induced by short-term exposure to TNF-alpha. This could partly explain the toxic effects of TNF-alpha on VSMCs that account for cardiovascular diseases. (C) 2011 Elsevier Ireland Ltd. All rights reserved.
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