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- Hülsmann, Lisa, et al.
(författare)
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Latitudinal patterns in stabilizing density dependence of forest communities
- 2024
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Ingår i: Nature. - 0028-0836 .- 1476-4687. ; 627, s. 564-571
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Tidskriftsartikel (refereegranskat)abstract
- Numerous studies have shown reduced performance in plants that are surrounded by neighbours of the same species1,2, a phenomenon known as conspecific negative density dependence (CNDD)3. A long-held ecological hypothesis posits that CNDD is more pronounced in tropical than in temperate forests4,5, which increases community stabilization, species coexistence and the diversity of local tree species6,7. Previous analyses supporting such a latitudinal gradient in CNDD8,9 have suffered from methodological limitations related to the use of static data10–12. Here we present a comprehensive assessment of latitudinal CNDD patterns using dynamic mortality data to estimate species-site-specific CNDD across 23 sites. Averaged across species, we found that stabilizing CNDD was present at all except one site, but that average stabilizingCNDD was not stronger toward the tropics. However, in tropical tree communities, rare and intermediate abundant species experienced stronger stabilizing CNDD than did common species. This pattern was absent in temperate forests, which suggests that CNDD influences species abundances more strongly in tropical forests than it does in temperate ones13. We also found that interspecific variation in CNDD, which might attenuate its stabilizing effect on species diversity14,15, was high but not significantly different across latitudes. Although the consequences of these patterns for latitudinal diversity gradients are difficult to evaluate, we speculate that a more effective regulation of population abundances could translate into greater stabilization of tropical tree communities and thus contribute to the high local diversity of tropical forests.
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| 2. |
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| 3. |
- Leite, Melina de Souza, et al.
(författare)
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Major axes of variation in tree demography across global forests
- 2024
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Ingår i: Ecography. - 0906-7590 .- 1600-0587.
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Tidskriftsartikel (refereegranskat)abstract
- The future trajectory of global forests is closely intertwined with tree demography, and a major fundamental goal in ecology is to understand the key mechanisms governing spatio-temporal patterns in tree population dynamics. While previous research has made substantial progress in identifying the mechanisms individually, their relative importance among forests remains unclear mainly due to practical limitations. One approach to overcome these limitations is to group mechanisms according to their shared effects on the variability of tree vital rates and quantify patterns therein. We developed a conceptual and statistical framework (variance partitioning of Bayesian multilevel models) that attributes the variability in tree growth, mortality, and recruitment to variation in species, space, and time, and their interactions – categories we refer to as organising principles (OPs). We applied the framework to data from 21 forest plots covering more than 2.9 million trees of approximately 6500 species. We found that differences among species, the species OP, proved a major source of variability in tree vital rates, explaining 28–33% of demographic variance alone, and 14–17% in interaction with space, totalling 40–43%. Our results support the hypothesis that the range of vital rates is similar across global forests. However, the average variability among species declined with species richness, indicating that diverse forests featured smaller interspecific differences in vital rates. Moreover, decomposing the variance in vital rates into the proposed OPs showed the importance of unexplained variability, which includes individual variation, in tree demography. A focus on how demographic variance is organized in forests can facilitate the construction of more targeted models with clearer expectations of which covariates might drive a vital rate. This study therefore highlights the most promising avenues for future research, both in terms of understanding the relative contributions of groups of mechanisms to forest demography and diversity, and for improving projections of forest ecosystems.
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| 6. |
- Aimo, Alberto, et al.
(författare)
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Cardiac remodelling - Part 2: Clinical, imaging and laboratory findings. A review from the Study Group on Biomarkers of the Heart Failure Association of the European Society of Cardiology
- 2022
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Ingår i: European Journal of Heart Failure. - : WILEY. - 1388-9842 .- 1879-0844. ; 24:6, s. 944-958
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Forskningsöversikt (refereegranskat)abstract
- In patients with heart failure, the beneficial effects of drug and device therapies counteract to some extent ongoing cardiac damage. According to the net balance between these two factors, cardiac geometry and function may improve (reverse remodelling, RR) and even completely normalize (remission), or vice versa progressively deteriorate (adverse remodelling, AR). RR or remission predict a better prognosis, while AR has been associated with worsening clinical status and outcomes. The remodelling process ultimately involves all cardiac chambers, but has been traditionally evaluated in terms of left ventricular volumes and ejection fraction. This is the second part of a review paper by the Study Group on Biomarkers of the Heart Failure Association of the European Society of Cardiology dedicated to ventricular remodelling. This document examines the proposed criteria to diagnose RR and AR, their prevalence and prognostic value, and the variables predicting remodelling in patients managed according to current guidelines. Much attention will be devoted to RR in patients with heart failure with reduced ejection fraction because most studies on cardiac remodelling focused on this setting.
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| 7. |
- Büntgen, Ulf, et al.
(författare)
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Horn growth variation and hunting selection of the Alpine ibex
- 2018
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Ingår i: Journal of Animal Ecology. - : Wiley. - 0021-8790 .- 1365-2656. ; 87:4, s. 1069-1079
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Tidskriftsartikel (refereegranskat)abstract
- 1. Selective hunting can affect demographic characteristics and phenotypic traits of the targeted species. Hunting systems often involve harvesting quotas based on sex, age and/or size categories to avoid selective pressure. However, it is difficult to assess whether such regulations deter hunters from targeting larger trophy animals with longer horns that may have evolutionary consequences.2. Here, we compile 44,088 annually resolved and absolutely dated measurements of Alpine ibex (Capra ibex) horn growth increments from 8,355 males, harvested between 1978 and 2013, in the eastern Swiss Canton of Grisons. We aim to determine whether male ibex with longer horns were preferentially targeted, causing animals with early rapid horn growth to have shorter lives, and whether such hunting selection translated into long-term trends in horn size over the past four decades.3. Results show that medium-to longer-horned adult males had a higher probability of being harvested than shorter-horned individuals of the same age and that regulations do affect the hunters' behaviour. Nevertheless, phenotypic traits such as horn length, as well as body size and weight, remained stable over the study period.4. Although selective trophy hunting still occurs, it did not cause a measurable evolutionary response in Grisons' Alpine ibex populations; managed and surveyed since 1978. Nevertheless, further research is needed to understand whether phenotypic trait development is coinfluenced by other, potentially compensatory factors that may possibly mask the effects of selective, long-term hunting pressure.
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| 9. |
- Gonzalez, Arantxa, et al.
(författare)
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Cardiac remodelling - Part 1: From cells and tissues to circulating biomarkers. A review from the Study Group on Biomarkers of the Heart Failure Association of the European Society of Cardiology
- 2022
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Ingår i: European Journal of Heart Failure. - : WILEY. - 1388-9842 .- 1879-0844. ; 24:6, s. 927-943
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Forskningsöversikt (refereegranskat)abstract
- Cardiac remodelling refers to changes in left ventricular structure and function over time, with a progressive deterioration that may lead to heart failure (HF) development (adverse remodelling) or vice versa a recovery (reverse remodelling) in response to HF treatment. Adverse remodelling predicts a worse outcome, whilst reverse remodelling predicts a better prognosis. The geometry, systolic and diastolic function and electric activity of the left ventricle are affected, as well as the left atrium and on the long term even right heart chambers. At a cellular and molecular level, remodelling involves all components of cardiac tissue: cardiomyocytes, fibroblasts, endothelial cells and leucocytes. The molecular, cellular and histological signatures of remodelling may differ according to the cause and severity of cardiac damage, and clearly to the global trend toward worsening or recovery. These processes cannot be routinely evaluated through endomyocardial biopsies, but may be reflected by circulating levels of several biomarkers. Different classes of biomarkers (e.g. proteins, non-coding RNAs, metabolites and/or epigenetic modifications) and several biomarkers of each class might inform on some aspects on HF development, progression and long-term outcomes, but most have failed to enter clinical practice. This may be due to the biological complexity of remodelling, so that no single biomarker could provide great insight on remodelling when assessed alone. Another possible reason is a still incomplete understanding of the role of biomarkers in the pathophysiology of cardiac remodelling. Such role will be investigated in the first part of this review paper on biomarkers of cardiac remodelling.
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