| 1. |
- Householder, John Ethan, et al.
(författare)
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One sixth of Amazonian tree diversity is dependent on river floodplains
- 2024
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Ingår i: NATURE ECOLOGY & EVOLUTION. - 2397-334X. ; 8, s. 901-911
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Tidskriftsartikel (refereegranskat)abstract
- Amazonia's floodplain system is the largest and most biodiverse on Earth. Although forests are crucial to the ecological integrity of floodplains, our understanding of their species composition and how this may differ from surrounding forest types is still far too limited, particularly as changing inundation regimes begin to reshape floodplain tree communities and the critical ecosystem functions they underpin. Here we address this gap by taking a spatially explicit look at Amazonia-wide patterns of tree-species turnover and ecological specialization of the region's floodplain forests. We show that the majority of Amazonian tree species can inhabit floodplains, and about a sixth of Amazonian tree diversity is ecologically specialized on floodplains. The degree of specialization in floodplain communities is driven by regional flood patterns, with the most compositionally differentiated floodplain forests located centrally within the fluvial network and contingent on the most extraordinary flood magnitudes regionally. Our results provide a spatially explicit view of ecological specialization of floodplain forest communities and expose the need for whole-basin hydrological integrity to protect the Amazon's tree diversity and its function.
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| 2. |
- Lind, Jacob, et al.
(författare)
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Jakt på papperslösa gör oss till en polisstat
- 2016
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Ingår i: Svenska Dagbladet. - : Svenska Dagbladet. - 1101-2412. ; :2016-10-04
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Regeringen föreslår nio åtgärder för att hitta och utvisa papperslösa. Det kommer att slå hårt och främst gå ut över redan svaga och jagade människor. Vi uppmanar därför regeringen att ta tillbaka åtgärderna, skriver 43 forskare.
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| 3. |
- Luize, Bruno Garcia, et al.
(författare)
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Geography and ecology shape the phylogenetic composition of Amazonian tree communities
- 2024
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Ingår i: JOURNAL OF BIOGEOGRAPHY. - 0305-0270 .- 1365-2699. ; 51:7, s. 1163-1184
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Tidskriftsartikel (refereegranskat)abstract
- Aim: Amazonia hosts more tree species from numerous evolutionary lineages, both young and ancient, than any other biogeographic region. Previous studies have shown that tree lineages colonized multiple edaphic environments and dispersed widely across Amazonia, leading to a hypothesis, which we test, that lineages should not be strongly associated with either geographic regions or edaphic forest types. Location: Amazonia. Taxon: Angiosperms (Magnoliids; Monocots; Eudicots). Methods: Data for the abundance of 5082 tree species in 1989 plots were combined with a mega-phylogeny. We applied evolutionary ordination to assess how phylogenetic composition varies across Amazonia. We used variation partitioning and Moran's eigenvector maps (MEM) to test and quantify the separate and joint contributions of spatial and environmental variables to explain the phylogenetic composition of plots. We tested the indicator value of lineages for geographic regions and edaphic forest types and mapped associations onto the phylogeny. Results: In the terra firme and v & aacute;rzea forest types, the phylogenetic composition varies by geographic region, but the igap & oacute; and white-sand forest types retain a unique evolutionary signature regardless of region. Overall, we find that soil chemistry, climate and topography explain 24% of the variation in phylogenetic composition, with 79% of that variation being spatially structured (R-2 = 19% overall for combined spatial/environmental effects). The phylogenetic composition also shows substantial spatial patterns not related to the environmental variables we quantified (R-2 = 28%). A greater number of lineages were significant indicators of geographic regions than forest types. Main Conclusion: Numerous tree lineages, including some ancient ones (>66 Ma), show strong associations with geographic regions and edaphic forest types of Amazonia. This shows that specialization in specific edaphic environments has played a long-standing role in the evolutionary assembly of Amazonian forests. Furthermore, many lineages, even those that have dispersed across Amazonia, dominate within a specific region, likely because of phylogenetically conserved niches for environmental conditions that are prevalent within regions.
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| 4. |
- O'Connell, Kyle A., et al.
(författare)
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A Tale of Two Skates : Comparative Phylogeography of North American Skate Species with Implications for Conservation
- 2019
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Ingår i: Copeia. - 0045-8511 .- 1938-5110. ; 107:2, s. 297-304
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Tidskriftsartikel (refereegranskat)abstract
- Genomic data can provide novel insights into the natural history of oceanic species. These data can inform the management of vulnerable and slow-maturing species by estimating population structure, rates of migration, and the distribution of genetic diversity. In this study we focus on two protected elasmobranch species, the Winter Skate, Leucoraja ocellata, and the Little Skate, L. erinacea. We use genome-wide SNPs to estimate population structure, and quantify migration and genetic diversity among both species from four sampling localities across the Atlantic coast of North America. We find that species of Leucoraja are generally isolated by distance, although we infer some fine-scale population structure. Specifically, estimates of effective migration infer fine-scale population structure in L. ocellata between the northern sites of Georges Bank and the Mid-Atlantic sampling sites, whereas L. erinacea shows no evidence of population genetic structure in any analyses. We also found that genetic diversity is concentrated in the central sites of Georges Bank and the Mid-Atlantic Bight for L. ocellata, but is reduced at these two sites in L. erinacea, suggesting opposite distributions of genetic diversity between species. Thus, genomic data suggest that while species of Leucoraja lack discrete population structure, they likely employ only mid-range dispersal. These findings correspond to ecological studies that have found eco physiological differences between embryonic and juvenile Leucoraja from different localities. Taken together, small-bodied skate research emphasizes the importance of local adaptive plasticity for marine species, even without population genetic structure. Conservation strategies should focus on managing the portions of the Atlantic coast considered most vital to reproduction of Leucoraja, but should not recognize multiple populations across their range.
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| 5. |
- Rodarte, Elsa M, et al.
(författare)
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Munc13 proteins control regulated exocytosis in mast cells.
- 2018
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 293:1, s. 345-358
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Tidskriftsartikel (refereegranskat)abstract
- Mast cells (MCs) are involved in host defenses against pathogens and inflammation. Stimulated MCs release substances stored in their granules via regulated exocytosis. In other cell types, Munc13 (mammalian homolog of Caenorhabditis elegans uncoordinated gene 13) proteins play essential roles in regulated exocytosis. Here, we found that MCs express Munc13-2 and -4, and we studied their roles using global and conditional knock-out (KO) mice. In a model of systemic anaphylaxis, we found no difference between WT and Munc13-2 KO mice, but global and MC-specific Munc13-4 KO mice developed less hypothermia. This protection correlated with lower plasma histamine levels and with histological evidence of defective MC degranulation but not with changes in MC development, distribution, numbers, or morphology. In vitro assays revealed that the defective response in Munc13-4-deficient MCs was limited to regulated exocytosis, leaving other MC secretory effector responses intact. Single cell capacitance measurements in MCs from mouse mutants differing in Munc13-4 expression levels in their MCs revealed that as levels of Munc13-4 decrease, the rate of exocytosis declines first, and then the total amount of exocytosis decreases. A requirement for Munc13-2 in MC exocytosis was revealed only in the absence of Munc13-4. Electrophysiology and EM studies uncovered that the number of multigranular compound events (i.e. granule-to-granule homotypic fusion) was severely reduced in the absence of Munc13-4. We conclude that although Munc13-2 plays a minor role, Munc13-4 is essential for regulated exocytosis in MCs, and that this MC effector response is required for a full anaphylactic response.
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| 6. |
- Sigvardsdotter, Erika, 1981-
(författare)
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Presenting the Absent : An Account of Undocumentedness in Sweden
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis provides an ethnography and critical phenomenology of undocumentedness in the Swedish context. By attending to the forces and processes that circumscribe the life-worlds of undocumented persons, as well as the phenomenology and essential experiences of their condition, a complex and multi-layered illustration of what undocumentedness is and means is successively presented. Employing a dual conceptualization of the state, as a juridico-political construct as well as a practiced and embodied set of institutions, the undocumented position emerges as a legal category defined only through omission, produced and reproduced through administrative routine and practice. The health care sector provides empirical examples of state-undocumented interaction where the physical and corporeal presence of the officially absent becomes irrefutable. This research suggests that the Swedish welfare state – universalistic, comprehensive and with digitized administrative routines – becomes a particularly austere environment in which to be undocumented. Drawing on interviews with regional and local health care administrators, NGO-clinics’ representatives and health professionals, as well as extensive participatory observation and interviews with undocumented persons, I argue that the undocumented condition is characterized by simultaneous absence and presence, and a correspondingly paradoxical spatiality. I suggest that the official absence and deportability of undocumented persons deprives them of the capacity to define space and, in an Arendtian sense, appear as themselves to others. There are, however, some opportunities for embodied political protest and dissensus. The paradoxical qualities of the absent-present condition manipulate the undocumented mode of being-in-the-world and I argue that alienation and disorientation are essential experiences of the undocumented situation.
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| 7. |
- ter Steege, Hans, et al.
(författare)
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Mapping density, diversity and species-richness of the Amazon tree flora
- 2023
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Ingår i: COMMUNICATIONS BIOLOGY. - 2399-3642. ; 6:1
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Tidskriftsartikel (refereegranskat)abstract
- Using 2.046 botanically-inventoried tree plots across the largest tropical forest on Earth, we mapped tree species-diversity and tree species-richness at 0.1-degree resolution, and investigated drivers for diversity and richness. Using only location, stratified by forest type, as predictor, our spatial model, to the best of our knowledge, provides the most accurate map of tree diversity in Amazonia to date, explaining approximately 70% of the tree diversity and species-richness. Large soil-forest combinations determine a significant percentage of the variation in tree species-richness and tree alpha-diversity in Amazonian forest-plots. We suggest that the size and fragmentation of these systems drive their large-scale diversity patterns and hence local diversity. A model not using location but cumulative water deficit, tree density, and temperature seasonality explains 47% of the tree species-richness in the terra-firme forest in Amazonia. Over large areas across Amazonia, residuals of this relationship are small and poorly spatially structured, suggesting that much of the residual variation may be local. The Guyana Shield area has consistently negative residuals, showing that this area has lower tree species-richness than expected by our models. We provide extensive plot meta-data, including tree density, tree alpha-diversity and tree species-richness results and gridded maps at 0.1-degree resolution. A study mapping the tree species richness in Amazonian forests shows that soil type exerts a strong effect on species richness, probably caused by the areas of these forest types. Cumulative water deficit, tree density and temperature seasonality affect species richness at a regional scale.
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