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1.
Proc Natl Acad Sci U S A ; 119(25): e2026733119, 2022 06 21.
Artigo em Inglês | MEDLINE | ID: mdl-35709320

RESUMO

Safeguarding Earth's tree diversity is a conservation priority due to the importance of trees for biodiversity and ecosystem functions and services such as carbon sequestration. Here, we improve the foundation for effective conservation of global tree diversity by analyzing a recently developed database of tree species covering 46,752 species. We quantify range protection and anthropogenic pressures for each species and develop conservation priorities across taxonomic, phylogenetic, and functional diversity dimensions. We also assess the effectiveness of several influential proposed conservation prioritization frameworks to protect the top 17% and top 50% of tree priority areas. We find that an average of 50.2% of a tree species' range occurs in 110-km grid cells without any protected areas (PAs), with 6,377 small-range tree species fully unprotected, and that 83% of tree species experience nonnegligible human pressure across their range on average. Protecting high-priority areas for the top 17% and 50% priority thresholds would increase the average protected proportion of each tree species' range to 65.5% and 82.6%, respectively, leaving many fewer species (2,151 and 2,010) completely unprotected. The priority areas identified for trees match well to the Global 200 Ecoregions framework, revealing that priority areas for trees would in large part also optimize protection for terrestrial biodiversity overall. Based on range estimates for >46,000 tree species, our findings show that a large proportion of tree species receive limited protection by current PAs and are under substantial human pressure. Improved protection of biodiversity overall would also strongly benefit global tree diversity.


Assuntos
Efeitos Antropogênicos , Biodiversidade , Conservação dos Recursos Naturais , Ecossistema , Árvores , Conservação dos Recursos Naturais/métodos , Humanos , Filogenia , Árvores/classificação
2.
An Acad Bras Cienc ; 94(1): e20201079, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35476061

RESUMO

The South Brazilian grasslands (Campos Sulinos) form the dominant vegetation in southern Brazil. They are species-rich ecosystems that occur under distinct geomorphological and climatic conditions but spatial variation of plant species diversity remains understudied. Here, we present a detailed description of plant communities across the region. Our data were obtained in 1080 plots, representing well-preserved grasslands in different ecological systems. Apart from describing alpha and beta diversity, we investigated the relations of plant communities with environmental features. We identified 759 plant species and found clear differences in community composition across the region. Northern and Southern highland grasslands, humid and dry coastal grasslands and the mesic Pampa grassland were clearly distinct, related to climatic and edaphic features. While species abundance distribution was markedly uneven, local species richness was high, above 20 species/m2, especially in the highlands and in mesic Pampa sites, on shallow soils. The predominant component of beta diversity was species turnover, which suggests that a network of well-conserved grasslands distributed across the region would be the best strategy to protect plant diversity. Our results establish regionalized reference values for richness and diversity that can be useful for initiatives of restoration and conservation of these grasslands.


Assuntos
Ecossistema , Pradaria , Biodiversidade , Brasil , Plantas , Valores de Referência
3.
Hum Reprod ; 36(5): 1310-1325, 2021 04 20.
Artigo em Inglês | MEDLINE | ID: mdl-33454781

RESUMO

STUDY QUESTION: Is the microRNA (miRNA) expression pattern of cumulus oophorus cells (COCs) in women undergoing medically assisted reproduction (MAR) procedures differentially modulated according to patient age and gonadotropin treatment strategy? SUMMARY ANSWER: Maternal age is an independent factor impacting miRNA expression in COCs while gonadotropin treatment may affect follicular miRNA expression and IVF efficacy. WHAT IS KNOWN ALREADY: Epigenetic mechanisms in female infertility are complex and poorly studied. DNA methylation, histone modifications, miRNAs and nucleosome positioning influence cellular machinery through positive and negative feedback mechanisms either alone or interactively. miRNAs are important regulators during oogenesis, spermatogenesis and early embryogenesis, and are reported to play a role in regulating crosstalk between the oocyte and COCs. Although miRNome analysis has been performed in female human reproductive tissues (endometrium, myometrium, cervix and ovaries), epigenetic modifications in women with infertility have not been explored in detail. In addition, the impact of gonadotropin treatments during MAR on miRNA expression in COCs has not been fully investigated. STUDY DESIGN, SIZE, DURATION: This study was carried out in 53 COC samples obtained from mature metaphase II (MII) oocytes in 53 women undergoing MAR treatment. A total of 38 samples for assay development were pooled by maternal age and gonadotropin treatment into four predetermined subgroups: ≥36 years and recombinant human FSH (r-hFSH), n = 10; ≥36 years and r-hFSH+ recombinant human-luteinizing hormone (r-hLH), n = 10; ≤35 years and r-hFSH, n = 9; ≤35 years and r-hFSH+r-hLH, n = 9. miRNome profiles were determined and compared between subgroups. Expression of defined miRNAs was validated in the remaining fifteen samples, representative of each subgroup, by quantitative polymerase chain reaction (PCR). PARTICIPANTS/MATERIALS, SETTING, METHODS: COCs were processed for miRNA-enriched total RNA extraction and pooled in homogeneous subgroups to obtain a sufficient amount and quality of starting material to perform the analysis. Each pooled sample underwent miRNA profiling using PCR assay system to examine expression of 752 human miRNAs without pre-amplification. Data were analyzed using the delta-delta Ct method for relative quantitation and prediction of target genes (with at least four algorithms predicting the same miRNA-gene interaction pair (HIT)>4). The miRSystem database provided functional annotation enrichment (raw P-value <0.05) of co-expressed miRNAs. MAIN RESULTS AND THE ROLE OF CHANCE: We found distinctive miRNA expression profiles in each subgroup correlating with age and MAR stimulation. In addition, a number of selective and co-expressed miRNAs were revealed by comparative analysis. A cluster of 37 miRNAs were commonly but differentially expressed in all four pools. Significant differences were observed in expression regulation of 37 miRNAs between age groups (≤35 or ≥36) in women receiving r-hFSH+r-hLH compared to those receiving r-hFSH alone. Higher concentrations and increased numbers of miRNAs were recorded in younger than in older patients, regardless of treatment. Functional and expression studies performed to retrieve common miRNome profiles revealed an enrichment of biological functions in oocyte growth and maturation, embryo development, steroidogenesis, ovarian hyperstimulation, apoptosis and cell survival, glucagon and lipid metabolism, and cell trafficking. The highest scored pathways of target genes of the 37 common miRNAs were associated with mitogen-activated protein kinase (MAPK) signaling pathways, G alpha signaling, transcription regulation, tight junctions, RNA polymerase I and III, and mitochondrial transcription. We identified a potential age- and MAR stimulation-dependent signature in the miRNA landscape of COCs. LIMITATIONS, REASONS FOR CAUTION: We cannot rule out the possibility that other unknown individual genetic or clinical factors may have interfered with the reported results. Since miRNA profiling was conducted with a predefined array of target probes, other miRNA molecules, potentially modulated by age and hormonal stimulation, may have been missed in this study. WIDER IMPLICATIONS OF THE FINDINGS: miRNA expression in COCs is modulated by gonadotropin treatment and correlates strongly with age. A better understanding of the expression patterns and functions of miRNAs may lead to the development of novel therapeutics to treat ovarian dysfunction and improve fertility in older women. STUDY FUNDING/COMPETING INTEREST: This study was funded by Merck KGaA, Darmstadt, Germany. All authors declared no competing interest, except SL and TD who are fully employed by Merck KGaA. TRIAL REGISTRATION NUMBER: N/A.


Assuntos
Células do Cúmulo , Oócitos , Idoso , Feminino , Fertilização in vitro , Alemanha , Humanos , Indução da Ovulação
4.
Oecologia ; 196(3): 633-647, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34146131

RESUMO

Progress in phylogenetic community ecology is often limited by the availability of phylogenetic information and the lack of appropriate methods and solutions to deal with this problem. We estimate the effect of the lack of phylogenetic information on the relations among taxa measured by commonly used phylogenetic metrics in comparative studies and community ecology, namely: Blomberg's K phylogenetic signal, Faith's Phylogenetic Diversity (PD), Mean Phylogenetic Distance (MPD) and Mean Nearest Taxon Distance (MNTD). To overcome this problem, we tested two possible solutions: Polytomic trees and Operational trees. Our results show that the effects on K values strongly depended on the level of phylogenetic signal. In the case of the community metrics, the effects were insensitive to the patterns of species distribution in the communities. Community metrics tended to be overestimated with both Polytomic and Operational trees, but the overestimation was higher with Polytomic trees. PD and MPD metrics were less biased than MNTD metric. We show that the lack of phylogenetic resolution is not necessarily problematic for all analyses and that its effect will depend on the chosen metric and on the solutions used to deal with the problem. Based on our results, we suggest that ecologists should prefer the Operational tree solution to remove polytomies in the phylogenetic tree and take careful consideration while designing experiments, and analyzing and interpreting the results of phylogenetic metrics.


Assuntos
Ecologia , Filogenia , Incerteza
5.
An Acad Bras Cienc ; 93(2): e20201604, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33852672

RESUMO

The Program for Biodiversity Research (PPBio) is an innovative program designed to integrate all biodiversity research stakeholders. Operating since 2004, it has installed long-term ecological research sites throughout Brazil and its logic has been applied in some other southern-hemisphere countries. The program supports all aspects of research necessary to understand biodiversity and the processes that affect it. There are presently 161 sampling sites (see some of them at Supplementary Appendix), most of which use a standardized methodology that allows comparisons across biomes and through time. To date, there are about 1200 publications associated with PPBio that cover topics ranging from natural history to genetics and species distributions. Most of the field data and metadata are available through PPBio web sites or DataONE. Metadata is available for researchers that intend to explore the different faces of Brazilian biodiversity spatio-temporal variation, as well as for managers intending to improve conservation strategies. The Program also fostered, directly and indirectly, local technical capacity building, and supported the training of hundreds of undergraduate and graduate students. The main challenge is maintaining the long-term funding necessary to understand biodiversity patterns and processes under pressure from global environmental changes.


Assuntos
Biodiversidade , Ecossistema , Brasil , Conservação dos Recursos Naturais , Humanos , Conhecimento
6.
New Phytol ; 226(4): 1117-1128, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-31943225

RESUMO

The benefits of the arbuscular mycorrhizal (AM) symbiosis between plants and fungi are modulated by the functional characteristics of both partners. However, it is unknown to what extent functionally distinct groups of plants naturally associate with different AM fungi. We reanalysed 14 high-throughput sequencing data sets describing AM fungal communities associating with plant individuals (2427) belonging to 297 species. We examined how root-associating AM fungal communities varied between plants with different growth forms, photosynthetic pathways, CSR (competitor, stress-tolerator, ruderal) strategies, mycorrhizal statuses and N-fixing statuses. AM fungal community composition differed in relation to all studied plant functional groups. Grasses, C4 and nonruderal plants were characterised by high AM fungal alpha diversity, while C4 , ruderal and obligately mycorrhizal plants were characterised by high beta diversity. The phylogenetic diversity of AM fungi, a potential surrogate for functional diversity, was higher among forbs than other plant growth forms. Putatively ruderal (previously cultured) AM fungi were disproportionately associated with forbs and ruderal plants. There was phylogenetic correlation among AM fungi in the degree of association with different plant growth forms and photosynthetic pathways. Associated AM fungal communities constitute an important component of plant ecological strategies. Functionally different plants associate with distinct AM fungal communities, linking mycorrhizal associations with functional diversity in ecosystems.


Assuntos
Micobioma , Micorrizas , Ecossistema , Filogenia , Raízes de Plantas , Plantas , Microbiologia do Solo , Simbiose
7.
Hum Reprod ; 33(5): 887-894, 2018 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-29481647

RESUMO

STUDY QUESTION: Are cohesins SA1/SA2 and the NAD-dependent deacetylase SIRT1 involved in telomere homeostasis of cumulus cells and thus eligible as biomarkers of follicular physiology and ovarian aging? SUMMARY ANSWER: SA1/SA2 cohesins and SIRT1 are associated with telomere length in cumulus cells and may be eligible biomarkers of follicular physiology and ovarian aging. WHAT IS KNOWN ALREADY: In somatic cells, cohesins SA1/SA2 mediate sister chromatid cohesion at the telomere termini (for SA1) and along chromatid arms (for SA2). The NAD+-dependent protein deacetylase Sirtuin 1 (SIRT1), which preserves DNA integrity from oxidative stress, may also modulate genome stability and telomere length. STUDY DESIGN, SIZE, DURATION: Collectively 280 cumulus/oocyte complex samples were recovered from a total of 50 women undergoing in vitro fertilization. PARTICIPANTS/MATERIALS, SETTING, METHODS: Cumulus cells were separated from the oocyte-cumulus complex. DNA and total mRNA were extracted from cumulus cells and assayed for telomere length and for SA1, SA2 and SIRT1 gene expression profiling. Telomere length was determined by quantitave PCR and analyzed relative to the single copy of the housekeeping gene (albumin) to generate a T/S ratio (Telomere/single copy gene). Gene expression levels of SA1, SA2 and SIRT1 mRNA were assayed by quantitative RT-PCR and confirmed by western blotting and immunofluorescent studies (SIRT1). SA1/SA2 and SIRT1 gene expression levels and telomere length analysis of patients/samples were ranked in relation to their clinical setting parameters (BMI, age) and to the number of oocyte retrieved. MAIN RESULTS AND THE ROLE OF CHANCE: SA1 and SA2 transcripts were both detected in all cumulus cells analyzed and the relative amount showed a clear decreasing trend according to the age of patients. A significant increase in SA1 and SA2 was disclosed in high responder women (>6 oocytes retrieved) compared to poor responders (<4 oocytes) (P < 0.05). Furthermore, statistically significant positive correlations were also recorded between the transcripts levels of the two cohesin molecules (r = 0.89; P < 0.05) and, to a lesser extent, between telomere length and SA1 (r = 0.42; P < 0.001) and SA2 (r = 0.36; P < 0.001) mRNA levels. SIRT1 expression was also significantly increased in high responders (>6 oocytes) compared to poor responders. Significant correlations were found between SIRT1 and SA1 (r = 0.69; P < 0.001), between SIRT1 and SA2 (r = 0.78; P < 0.001), and between SIRT1 and telomere length (r = 0.36; P < 0.001). However, in the older patient group (>38 years), SIRT1 mRNA levels were twice as high as the levels recorded in the younger patient cohort (<34 years). Western blot analysis and immunofluorescent studies confirmed the increments in SIRT1 protein levels in patients over 38 years old. LARGE SCALE DATA: N/A. LIMITATIONS, REASONS FOR CAUTION: Cumulus/oocyte complexes were retrieved by patients undergoing ovarian stimulation protocol for IVF. We cannot exclude the possibility that different stimulation protocols affect the correlations highlighted in this study. Future investigations should shed light on cumulus cells molecular profile according to different stimulation protocols. WIDER IMPLICATIONS OF THE FINDINGS: The overall results of our study point to the involvement of cohesins SA1/SA2 and SIRT1 deacetylase in telomere homeostasis in cumulus cells and highlight their possible eligibility as biomarkers of follicular physiology and ovarian aging. STUDY FUNDING/COMPETING INTEREST(S): Merck Serono S.P.A Italy sponsored the study with financial support. There are no competing interests to declare.


Assuntos
Proteínas de Ciclo Celular/metabolismo , Proteínas Cromossômicas não Histona/metabolismo , Células do Cúmulo/metabolismo , Ovário/metabolismo , Sirtuína 1/metabolismo , Homeostase do Telômero/fisiologia , Adulto , Biomarcadores/metabolismo , Feminino , Humanos , Recuperação de Oócitos , Folículo Ovariano/metabolismo , Indução da Ovulação , Telômero/metabolismo , Coesinas
9.
Ecol Lett ; 18(12): 1406-19, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26415616

RESUMO

Recent studies have shown that accounting for intraspecific trait variation (ITV) may better address major questions in community ecology. However, a general picture of the relative extent of ITV compared to interspecific trait variation in plant communities is still missing. Here, we conducted a meta-analysis of the relative extent of ITV within and among plant communities worldwide, using a data set encompassing 629 communities (plots) and 36 functional traits. Overall, ITV accounted for 25% of the total trait variation within communities and 32% of the total trait variation among communities on average. The relative extent of ITV tended to be greater for whole-plant (e.g. plant height) vs. organ-level traits and for leaf chemical (e.g. leaf N and P concentration) vs. leaf morphological (e.g. leaf area and thickness) traits. The relative amount of ITV decreased with increasing species richness and spatial extent, but did not vary with plant growth form or climate. These results highlight global patterns in the relative importance of ITV in plant communities, providing practical guidelines for when researchers should include ITV in trait-based community and ecosystem studies.


Assuntos
Biodiversidade , Fenótipo , Fenômenos Fisiológicos Vegetais , Especificidade da Espécie
10.
Ambio ; 44(2): 154-62, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24973054

RESUMO

Ecological science contributes to solving a broad range of environmental problems. However, lack of ecological literacy in practice often limits application of this knowledge. In this paper, we highlight a critical but often overlooked demand on ecological literacy: to enable professionals of various careers to apply scientific knowledge when faced with environmental problems. Current university courses on ecology often fail to persuade students that ecological science provides important tools for environmental problem solving. We propose problem-based learning to improve the understanding of ecological science and its usefulness for real-world environmental issues that professionals in careers as diverse as engineering, public health, architecture, social sciences, or management will address. Courses should set clear learning objectives for cognitive skills they expect students to acquire. Thus, professionals in different fields will be enabled to improve environmental decision-making processes and to participate effectively in multidisciplinary work groups charged with tackling environmental issues.


Assuntos
Ecologia/educação , Ecologia/tendências , Resolução de Problemas , Aprendizagem Baseada em Problemas/tendências , Ecologia/normas , Humanos , Aprendizagem Baseada em Problemas/normas
11.
Bioinformatics ; 28(15): 2067-8, 2012 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-22668789

RESUMO

SUMMARY: SYNCSA is an R package for the analysis of metacommunities based on functional traits and phylogeny of the community components. It offers tools to calculate several matrix correlations that express trait-convergence assembly patterns, trait-divergence assembly patterns and phylogenetic signal in functional traits at the species pool level and at the metacommunity level. AVAILABILITY AND IMPLEMENTATION: SYNCSA is a package for the R environment, under a GPL-2 open-source license and freely available on CRAN official web server for R (http://cran.r-project.org). CONTACT: vanderleidebastiani@yahoo.com.br.


Assuntos
Biota , Ecologia/métodos , Filogenia , Software , Biologia Computacional/métodos
12.
Nat Genet ; 10(3): 279-87, 1995 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-7670465

RESUMO

We report the generation and characterization of mice lacking adenosine deaminase (ADA). In humans, absence of ADA causes severe combined immunodeficiency. In contrast, ADA-deficient mice die perinatally with marked liver-cell degeneration, but lack abnormalities in the thymus. The ADA substrates, adenosine and deoxyadenosine, are increased in ADA-deficient mice. Adenine deoxyribonucleotides are only modestly elevated, whereas S-adenosylhomocysteine hydrolase activity is reduced more than 85%. Consequently, the ratio of S-adenosylhomocysteine (AdoMet) to S-adenosyl homocysteine (AdoHcy) is reduced threefold in liver. We conclude that ADA plays a more critical role in murine than human fetal development. The murine liver pathology may be due to AdoHcy-mediated inhibition of AdoMet-dependent transmethylation reactions.


Assuntos
Adenosina Desaminase/deficiência , Adenosina Desaminase/genética , Intestino Delgado/patologia , Fígado/patologia , Atelectasia Pulmonar/genética , Animais , Animais Recém-Nascidos , Sequência de Bases , Morte Celular , Primers do DNA/genética , Modelos Animais de Doenças , Desenvolvimento Embrionário e Fetal/genética , Desenvolvimento Embrionário e Fetal/fisiologia , Feminino , Marcação de Genes , Homozigoto , Humanos , Masculino , Metilação , Camundongos , Dados de Sequência Molecular , Mutação , Gravidez , Purinas/metabolismo , Imunodeficiência Combinada Severa/etiologia , Subpopulações de Linfócitos T/imunologia
13.
Sci Adv ; 9(14): eadd8553, 2023 04 05.
Artigo em Inglês | MEDLINE | ID: mdl-37018407

RESUMO

As Earth's climate has varied strongly through geological time, studying the impacts of past climate change on biodiversity helps to understand the risks from future climate change. However, it remains unclear how paleoclimate shapes spatial variation in biodiversity. Here, we assessed the influence of Quaternary climate change on spatial dissimilarity in taxonomic, phylogenetic, and functional composition among neighboring 200-kilometer cells (beta-diversity) for angiosperm trees worldwide. We found that larger glacial-interglacial temperature change was strongly associated with lower spatial turnover (species replacements) and higher nestedness (richness changes) components of beta-diversity across all three biodiversity facets. Moreover, phylogenetic and functional turnover was lower and nestedness higher than random expectations based on taxonomic beta-diversity in regions that experienced large temperature change, reflecting phylogenetically and functionally selective processes in species replacement, extinction, and colonization during glacial-interglacial oscillations. Our results suggest that future human-driven climate change could cause local homogenization and reduction in taxonomic, phylogenetic, and functional diversity of angiosperm trees worldwide.


Assuntos
Magnoliopsida , Humanos , Filogenia , Mudança Climática , Biodiversidade
14.
Nat Commun ; 13(1): 3185, 2022 06 08.
Artigo em Inglês | MEDLINE | ID: mdl-35676261

RESUMO

Due to massive energetic investments in woody support structures, trees are subject to unique physiological, mechanical, and ecological pressures not experienced by herbaceous plants. Despite a wealth of studies exploring trait relationships across the entire plant kingdom, the dominant traits underpinning these unique aspects of tree form and function remain unclear. Here, by considering 18 functional traits, encompassing leaf, seed, bark, wood, crown, and root characteristics, we quantify the multidimensional relationships in tree trait expression. We find that nearly half of trait variation is captured by two axes: one reflecting leaf economics, the other reflecting tree size and competition for light. Yet these orthogonal axes reveal strong environmental convergence, exhibiting correlated responses to temperature, moisture, and elevation. By subsequently exploring multidimensional trait relationships, we show that the full dimensionality of trait space is captured by eight distinct clusters, each reflecting a unique aspect of tree form and function. Collectively, this work identifies a core set of traits needed to quantify global patterns in functional biodiversity, and it contributes to our fundamental understanding of the functioning of forests worldwide.


Assuntos
Árvores , Biodiversidade , Florestas , Casca de Planta/fisiologia , Folhas de Planta/fisiologia , Raízes de Plantas/fisiologia , Sementes/fisiologia , Árvores/fisiologia , Madeira/fisiologia
15.
Nat Ecol Evol ; 6(1): 36-50, 2022 01.
Artigo em Inglês | MEDLINE | ID: mdl-34949824

RESUMO

Plant functional traits can predict community assembly and ecosystem functioning and are thus widely used in global models of vegetation dynamics and land-climate feedbacks. Still, we lack a global understanding of how land and climate affect plant traits. A previous global analysis of six traits observed two main axes of variation: (1) size variation at the organ and plant level and (2) leaf economics balancing leaf persistence against plant growth potential. The orthogonality of these two axes suggests they are differently influenced by environmental drivers. We find that these axes persist in a global dataset of 17 traits across more than 20,000 species. We find a dominant joint effect of climate and soil on trait variation. Additional independent climate effects are also observed across most traits, whereas independent soil effects are almost exclusively observed for economics traits. Variation in size traits correlates well with a latitudinal gradient related to water or energy limitation. In contrast, variation in economics traits is better explained by interactions of climate with soil fertility. These findings have the potential to improve our understanding of biodiversity patterns and our predictions of climate change impacts on biogeochemical cycles.


Assuntos
Ecossistema , Solo , Fenótipo , Folhas de Planta , Plantas
16.
Nat Commun ; 13(1): 4683, 2022 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-36050293

RESUMO

Global patterns of regional (gamma) plant diversity are relatively well known, but whether these patterns hold for local communities, and the dependence on spatial grain, remain controversial. Using data on 170,272 georeferenced local plant assemblages, we created global maps of alpha diversity (local species richness) for vascular plants at three different spatial grains, for forests and non-forests. We show that alpha diversity is consistently high across grains in some regions (for example, Andean-Amazonian foothills), but regional 'scaling anomalies' (deviations from the positive correlation) exist elsewhere, particularly in Eurasian temperate forests with disproportionally higher fine-grained richness and many African tropical forests with disproportionally higher coarse-grained richness. The influence of different climatic, topographic and biogeographical variables on alpha diversity also varies across grains. Our multi-grain maps return a nuanced understanding of vascular plant biodiversity patterns that complements classic maps of biodiversity hotspots and will improve predictions of global change effects on biodiversity.


Assuntos
Biodiversidade , Traqueófitas , Ecossistema , Plantas
17.
Ecol Lett ; 13(5): 587-96, 2010 May.
Artigo em Inglês | MEDLINE | ID: mdl-20337699

RESUMO

It is well known that species evolutionary history plays a crucial role in community assembly. Here, we offer a formal analytical framework to integrate in metacommunity analysis the species' phylogeny with their functional traits and abundances. We define phylogenetic structure of a community as phylogenetically weighted species composition. This is used to reveal patterns of phylogenetic community variation and to measure and test by specified null models the phylogenetic signal at the metacommunity level, which we distinguish from phylogenetic signal at the species pool level. The former indicates that communities more similar in their phylogenetic structure are also similar in their average trait values, which may indicate species' niche conservation for the given traits. We apply this framework to an example from grassland communities and find that traits with significant phylogenetic signal at the metacommunity level exhibit ecological filtering along the resource gradient, but since both mechanisms act independently on traits, niche conservatism is not supported.


Assuntos
Filogenia , Poaceae/genética , Modelos Genéticos , Especificidade da Espécie
18.
J Exp Med ; 172(3): 729-36, 1990 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-1974914

RESUMO

Amphotropic recombinant retroviruses were generated carrying sequences encoding human adenosine deaminase (ADA). Transcription of the human ADA gene was under control of a hybrid long terminal repeat in which the enhancer from the Moloney murine leukemia virus was replaced by an enhancer from the F101 host-range mutant of polyoma virus. Hemopoietic stem cells in murine bone marrow were infected with this virus under defined culture conditions. As a result, 59% of day-12 colony forming unit spleen (CFU-S) stem cells became infected without any in vitro selection. Infected CFU-S were shown to express human ADA before transplantation and this expression sustained upon in vivo maturation. Mice transplanted with infected bone marrow exhibited human ADA expression in lymphoid, myeloid, and erythroid cell types. Moreover, human ADA expression persisted in secondary and tertiary transplanted recipients showing that human ADA-expressing cells were derived from pluripotent stem cells. These characteristics of our amphotropic viruses make them promising tools in gene therapy protocols for the treatment of severe combined immunodeficiency caused by ADA deficiency. In this respect it is also relevant that the viral vector that served as backbone for the ADA vector was previously shown to be nonleukemogenic.


Assuntos
Adenosina Desaminase/genética , Vetores Genéticos , Transplante de Células-Tronco Hematopoéticas , Nucleosídeo Desaminases/genética , Retroviridae/genética , Animais , Southern Blotting , Transplante de Medula Óssea , Linhagem Celular , Células Cultivadas , DNA/genética , DNA/isolamento & purificação , Expressão Gênica , Humanos , Camundongos , Recombinação Genética
19.
PLoS One ; 15(1): e0227706, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31931512

RESUMO

Grazing exclusion may lead to biodiversity loss and homogenization of naturally heterogeneous and species-rich grassland ecosystems, and these effects may cascade to higher trophic levels and ecosystem properties. Although grazing exclusion has been studied elsewhere, the consequences of alleviating the disturbance regime in grassland ecosystems remain unclear. In this paper, we present results of the first five years of an experiment in native grasslands of southern Brazil. Using a randomized block experimental design, we examined the effects of three grazing treatments on plant and arthropod communities: (i) deferred grazing (i.e., intermittent grazing), (ii) grazing exclusion and (iii) a control under traditional continuous grazing, which were applied to 70 x 70 m experimental plots, in six regionally distributed blocks. We evaluated plant community responses regarding taxonomic and functional diversity (life-forms) in separate spatial components: alpha (1 x 1 m subplots), beta, and gamma (70 x 70 m plots), as well as the cascading effects on arthropod high-taxa. By estimating effect sizes (treatments vs. control) by bootstrap resampling, both deferred grazing and grazing exclusion mostly increased vegetation height, plant biomass and standing dead biomass. The effect of grazing exclusion on plant taxonomic diversity was negative. Conversely, deferred grazing increased plant taxonomic diversity, but both treatments reduced plant functional diversity. Reduced grazing pressure in both treatments promoted the break of dominance by prostrate species, followed by fast homogenization of vegetation structure towards dominance of ligneous and erect species. These changes in the plant community led to increases in high-taxa richness and abundance of vegetation-dwelling arthropod groups under both treatments, but had no detectable effects on epigeic arthropods. Our results indicate that decision-making regarding the conservation of southern Brazil grasslands should include both intensive and alleviated levels of grazing management, but not complete grazing exclusion, to maximize conservation results when considering plant and arthropod communities.


Assuntos
Artrópodes/fisiologia , Herbivoria , Poaceae/fisiologia , Animais , Artrópodes/classificação , Biodiversidade , Biomassa , Brasil , Conservação dos Recursos Naturais , Ecossistema , Pradaria , Poaceae/classificação
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