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  • 1
    Language: English
    In: Nature (London), 2013-05-30, Vol.497 (7451), p.611-614
    Description: Apes and Old World monkeys are prominent components of modern African and Asian ecosystems, yet the earliest phases of their evolutionary history have remained largely undocumented. The absence of crown catarrhine fossils older than ∼20 million years (Myr) has stood in stark contrast to molecular divergence estimates of ∼25-30 Myr for the split between Cercopithecoidea (Old World monkeys) and Hominoidea (apes), implying long ghost lineages for both clades. Here we describe the oldest known fossil 'ape', represented by a partial mandible preserving dental features that place it with 'nyanzapithecine' stem hominoids. Additionally, we report the oldest stem member of the Old World monkey clade, represented by a lower third molar. Both specimens were recovered from a precisely dated 25.2-Myr-old stratum in the Rukwa Rift, a segment of the western branch of the East African Rift in Tanzania. These finds extend the fossil record of apes and Old World monkeys well into the Oligocene epoch of Africa, suggesting a possible link between diversification of crown catarrhines and changes in the African landscape brought about by previously unrecognized tectonic activity in the East African rift system.
    Subject(s): Animals ; Apes ; Cercopithecidae - anatomy & histology ; Cercopithecidae - classification ; Divergent evolution ; Fossils ; History, Ancient ; Hominidae - anatomy & histology ; Hominidae - classification ; Mandible - anatomy & histology ; Natural history ; Observations ; Old-World monkeys ; Paleontology ; Phylogeny ; Research ; Tanzania ; Tooth - anatomy & histology
    ISSN: 0028-0836
    E-ISSN: 1476-4687
    Source: Academic Search Ultimate
    Source: Get It Now
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  • 2
    Language: English
    In: PloS one, 2011-02-15, Vol.6 (2), p.e16793-e16793
    Description: Inconspicuous basidiomycetes from the order Sebacinales are known to be involved in a puzzling variety of mutualistic plant-fungal symbioses (mycorrhizae), which presumably involve transport of mineral nutrients. Recently a few members of this fungal order not fitting this definition and commonly referred to as 'endophytes' have raised considerable interest by their ability to enhance plant growth and to increase resistance of their host plants against abiotic stress factors and fungal pathogens. Using DNA-based detection and electron microscopy, we show that Sebacinales are not only extremely versatile in their mycorrhizal associations, but are also almost universally present as symptomless endophytes. They occurred in field specimens of bryophytes, pteridophytes and all families of herbaceous angiosperms we investigated, including liverworts, wheat, maize, and the non-mycorrhizal model plant Arabidopsis thaliana. They were present in all habitats we studied on four continents. We even detected these fungi in herbarium specimens originating from pioneering field trips to North Africa in the 1830s/40s. No geographical or host patterns were detected. Our data suggest that the multitude of mycorrhizal interactions in Sebacinales may have arisen from an ancestral endophytic habit by specialization. Considering their proven beneficial influence on plant growth and their ubiquity, endophytic Sebacinales may be a previously unrecognized universal hidden force in plant ecosystems.
    Subject(s): Angiosperms ; Arabidopsis thaliana ; Basidiomycota - genetics ; Basidiomycota - isolation & purification ; Basidiomycota - ultrastructure ; Bioinformatics ; Biology ; Bryophytes ; Cellular Biology ; Continents ; Corn ; Deoxyribonucleic acid ; DNA ; DNA, Fungal - genetics ; Drug resistance in microorganisms ; Electron microscopy ; Endophytes ; Endophytes - genetics ; Endophytes - isolation & purification ; Endophytes - ultrastructure ; Epoxy resins ; Evolution ; Evolution, Molecular ; Fungi ; Host plants ; Life Sciences ; Microscopy ; Morphology ; Nutrients ; Phylogenetics ; Phylogeny ; Plant growth ; Plant Roots - microbiology ; Polymerase Chain Reaction ; Specialization ; Studies ; Symbiosis ; Triticum - microbiology ; Wheat
    ISSN: 1932-6203
    E-ISSN: 1932-6203
    Source: Academic Search Ultimate
    Source: PubMed Central
    Source: DOAJ Directory of Open Access Journals - Not for CDI Discovery
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  • 3
    Language: English
    In: Global change biology, 2016-11, Vol.22 (11), p.3804-3813
    Description: The interaction between xylem phenology and climate assesses forest growth and productivity and carbon storage across biomes under changing environmental conditions. We tested the hypothesis that patterns of wood formation are maintained unaltered despite the temperature changes across cold ecosystems. Wood microcores were collected weekly or biweekly throughout the growing season for periods varying between 1 and 13 years during 1998–2014 and cut in transverse sections for assessing the onset and ending of the phases of xylem differentiation. The data set represented 1321 trees belonging to 10 conifer species from 39 sites in the Northern Hemisphere and covering an interval of mean annual temperature exceeding 14 K. The phenological events and mean annual temperature of the sites were related linearly, with spring and autumnal events being separated by constant intervals across the range of temperature analysed. At increasing temperature, first enlarging, wall‐thickening and mature tracheids appeared earlier, and last enlarging and wall‐thickening tracheids occurred later. Overall, the period of wood formation lengthened linearly with the mean annual temperature, from 83.7 days at −2 °C to 178.1 days at 12 °C, at a rate of 6.5 days °C−1. April–May temperatures produced the best models predicting the dates of wood formation. Our findings demonstrated the uniformity of the process of wood formation and the importance of the environmental conditions occurring at the time of growth resumption. Under warming scenarios, the period of wood formation might lengthen synchronously in the cold biomes of the Northern Hemisphere.
    Subject(s): Analysis ; Biomes ; cambium ; Cell differentiation ; cell production ; climate change ; Cold Temperature ; Coniferophyta ; conifers ; Ecosystem ; Ecosystems ; Environmental aspects ; Global temperature changes ; growth ; Life Sciences ; meristem ; Plant Development ; Seasons ; secondary wall formation ; Trees ; Vegetal Biology ; Xylem
    ISSN: 1354-1013
    E-ISSN: 1365-2486
    Source: Hellenic Academic Libraries Link
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  • 4
    Language: English
    In: eLife, 2014-04-08, Vol.3, p.e02131-e02131
    Description: Membrane trafficking is essential to fundamental processes in eukaryotic life, including cell growth and division. In plant cytokinesis, post-Golgi trafficking mediates a massive flow of vesicles that form the partitioning membrane but its regulation remains poorly understood. Here, we identify functionally redundant Arabidopsis ARF guanine-nucleotide exchange factors (ARF-GEFs) BIG1-BIG4 as regulators of post-Golgi trafficking, mediating late secretion from the trans-Golgi network but not recycling of endocytosed proteins to the plasma membrane, although the TGN also functions as an early endosome in plants. In contrast, BIG1-4 are absolutely required for trafficking of both endocytosed and newly synthesized proteins to the cell-division plane during cytokinesis, counteracting recycling to the plasma membrane. This change from recycling to secretory trafficking pathway mediated by ARF-GEFs confers specificity of cargo delivery to the division plane and might thus ensure that the partitioning membrane is completed on time in the absence of a cytokinesis-interphase checkpoint. DOI: http://dx.doi.org/10.7554/eLife.02131.001.
    Subject(s): Arabidopsis ; Arabidopsis - metabolism ; Arabidopsis Proteins - metabolism ; Arabidopsis Proteins - secretion ; ARF-GEF ; Cell Biology ; Cell Division ; Cytokinesis ; Endocytosis ; Flowers & plants ; gegulation of vesicle traffic ; Golgi apparatus ; Golgi Apparatus - metabolism ; Guanine ; Guanine nucleotide exchange factor ; Localization ; Membrane trafficking ; Microscopy ; Molecular biology ; Phylogenetics ; Physiology ; Plant Biology ; post-Golgi trafficking ; Protein Transport ; Proteins ; Recycling ; secretion ; Seeds ; Software
    ISSN: 2050-084X
    E-ISSN: 2050-084X
    Source: PubMed Central
    Source: DOAJ Directory of Open Access Journals - Not for CDI Discovery
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  • 5
    Language: English
    In: Forests, 2019-11-01, Vol.10 (11), p.1024
    Description: In this work, we examine the effects of commercial thinning on stand volume and individual stem form in nine naturally regenerated black spruce (Picea mariana (Mill.) B.S.P.) stands. We compared these study sites with controls in the commercial boreal forest of northern Quebec, Canada. At stand level, dendrochronological data provided insight into changes in stand volume ten years after thinning. Analysis of a subsample of six individual trees from each commercially thinned stand and three individual trees from the controls illustrated the role of thinning on stem shape development. Although average volume increased for residual stems in thinned stands slightly more than in the controls (110% versus 106%), the treatment effect stand-level volume increment or stand-level total volume harvested (ten years after treatment) was not statistically significant. Moreover, at tree level, thinning did not significantly affect stem volume increment. However, radial growth increment significantly increased after treatment. Trees from commercially thinned stands showed a significantly higher growth increment along the lower first two-thirds of the stem. Response to thinning at tree level correlated strongly with the size and number of harvested competitors around a residual stem. We conclude that commercial thinning modified wood allocation rather than wood volume and did not affect taper and stem shape. These patterns of post-cutting growth are explained by wood allocation following thinning. After commercial thinning, growth increment is favored at the expense of height growth. As the treatment effect was found at the stem scale rather than at the stand scale, further research is needed in regard to commercial thinning treatments to investigate how to increase productivity at the stand scale.
    Subject(s): Forestry ; Life Sciences & Biomedicine ; Science & Technology
    ISSN: 1999-4907
    E-ISSN: 1999-4907
    Source: Web of Science - Science Citation Index Expanded - 2019〈img src="http://exlibris-pub.s3.amazonaws.com/fromwos-v2.jpg" /〉
    Source: DOAJ Directory of Open Access Journals - Not for CDI Discovery
    Source: ProQuest Central
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  • 6
    Language: English
    In: Frontiers in plant science, 2018, Vol.9, p.1061-1061
    Description: In Canada, new forestry practices involving the natural dynamics of tree growth and regeneration are proposed for integrating forest management with biodiversity. In particular, the current spruce budworm [ (Clemens)] outbreak in northeastern North America is forcing natural resource managers to clarify the potential interactions between natural disturbances and commercial thinning. The aim of this study was to investigate if the spruce budworm outbreak of the 1970s affected the responses of black spruce [ (Mill.) B.S.P.] to a subsequent thinning. Stem growth was reconstructed by measuring and cross-dating chronologies of tree-ring width of 1290 adult trees from 34 control and thinned stands within an area of 11,000 km in the boreal forest of the Saguenay-Lac-Saint-Jean region (QC, Canada). The treatment consisted of a low thinning performed during 1995-1999 that removed 25-35% of the basal area. Segmented models were applied to the tree-ring chronologies to define the growth pattern during the outbreak and thinning periods within a time window of 8 years, representing the average duration of the effects of defoliation on growth. Trees showed abrupt growth decreases during the outbreak, with the tree-ring index showing minimum values in 1977-1979. The tree-ring index had a flat trend before thinning, while it increased for 6-10 years after thinning. The growth pattern during the outbreak period was characterized by a reduction, mainly in trees with larger tree rings, while slow-growing trees showed less sensitivity to the disturbance. Thinning produced a significant increase in tree growth. No relationship was found between the effects of spruce budworm outbreaks in trees and the changes in growth pattern after thinning. If the timespan between the two disturbances exceeds 7 years, partial cutting can be applied independently of the growth reductions that had occurred during the outbreak. When applied in black spruce stands with high annual radial growth, thinning is expected to optimize the volume growth of the residual trees.
    Subject(s): Analysis ; boreal forest ; Choristoneura fumiferana ; dendroecology ; disturbance ; Forest thinning ; Growth (Plants) ; growth rate ; growth release ; Methods ; Picea mariana ; Plant Science ; Research ; Spruce budworm ; sylviculture
    ISSN: 1664-462X
    E-ISSN: 1664-462X
    Source: PubMed Central
    Source: DOAJ Directory of Open Access Journals - Not for CDI Discovery
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  • 7
    Language: English
    In: Annals of botany, 2008-11, Vol.102 (5), p.667-674
    Description: Background and Aims Studies on xylogenesis focus essentially on the stem, whereas there is basically no information about the intra-annual growth of other parts of the tree. As roots strongly influence carbon allocation and tree development, knowledge of the dynamics of xylem production and maturation in roots at a short time scale is required for a better understanding of the phenomenon of tree growth. This study compared cambial activity and xylem formation in stem and roots in two conifers of the boreal forest in Canada. Methods Wood microcores were collected weekly in stem and roots of ten Abies balsamea and ten Picea mariana during the 2004–2006 growing seasons. Cross-sections were cut using a rotary microtome, stained with cresyl violet acetate and observed under visible and polarized light. The number of cells in the cambial zone and in differentiation, plus the number of mature cells, was counted along the developing xylem. Key Results Xylem formation lasted from the end of May to the end of September, with no difference between stem and roots in 2004–2005. On the contrary, in 2006 a 1-week earlier beginning of cell differentiation was observed in the stem, with cell wall thickening and lignification in roots ending up to 22 d later than in the stem. Cell production in the stem was concentrated early in the season, in June, while most cell divisions in roots occurred 1 month later. Conclusions The intra-annual dynamics of growth observed in stem and roots could be related to the different amount of cells produced by the cambium and the patterns of air and soil temperature occurring in spring.
    Subject(s): Abies - cytology ; Abies - growth & development ; Abies balsamea ; Analysis of Variance ; boreal forest ; Cambium ; Cell Count ; Cell Differentiation ; cell wall thickening ; Cell walls ; Cellular differentiation ; lignification ; Original ; Picea - cytology ; Picea - growth & development ; Picea mariana ; Pine trees ; Plant roots ; Plant Roots - cytology ; Plant Roots - growth & development ; Plant Stems - cytology ; Plant Stems - growth & development ; root ; stem ; Stems ; Time Factors ; Tracheids ; Tree growth ; Trees ; Xylem ; Xylem - cytology ; Xylem - growth & development
    ISSN: 0305-7364
    E-ISSN: 1095-8290
    Source: JSTOR Life Sciences
    Source: JSTOR Ecology & Botany II
    Source: Academic Search Ultimate
    Source: PubMed Central
    Source: Alma/SFX Local Collection
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  • 8
    Language: English
    In: Annals of forest science., 2019-04-25, Vol.76 (2), p.1-13
    Description: • Key Message Wood properties were generally similar in unmanaged even-aged and uneven-aged black spruce stands. In contrast, in managed forests, wood density was higher in even-aged than in uneven-aged stands. As ring width is the discriminant factor, forest management should regulate the intensity of partial cutting to maintain a high wood density. • Context North American boreal forests experience recurrent disturbances, such as fire and insect outbreaks, that shape the structure of even-aged and uneven-aged stands. Ecosystem-based forest management practices, such as partial cutting, aim to increase timber yields, and these forest harvesting approaches are being applied more frequently. Although the influence of these practices on tree growth is well known, few studies have examined their impact on anatomy and density of the resulting wood. • Aim This research studied the relationships between wood properties and ring width and tree heights in even- and uneven-aged black spruce ( Picea mariana (Mill.) BSP) stands and how these relationships are modified following partial cutting. • Method Wood density (ring, earlywood, latewood, and maximum density) and anatomical traits (lumen area, cell-wall thickness, and tracheid length) were measured at breast height on the stem of black spruce trees. The measured wood properties were then correlated with ring width and stem height. • Results The model demonstrated significant correlations between most measured wood parameters and ring width with only small differences between even- and uneven-aged unmanaged stands. Five wood properties were influenced by tree height in even-aged and uneven-aged unmanaged plots. Partial cutting increased the number of significant relationships between wood properties (ring, latewood, maximum density, early- and latewood lumen area, tracheid length) and tree height. We detected differences in wood properties between even- and uneven-aged plots. Although we detected no change in average ring density, the variation of intra-annual density increased, due to changes in earlywood and latewood density that resulted in more heterogeneous rings. • Conclusion Partial cutting should take into consideration the age structure of the stand when the density of wood products matters.
    Subject(s): Age composition ; Biomedical and Life Sciences ; Boreal forests ; Change detection ; Correlation analysis ; Density ; Ecosystem management ; Environment ; Environment, general ; Environmental changes ; Even- and uneven-aged forest ; Forest ecosystems ; Forest harvesting ; Forest management ; Forestry ; Forestry Management ; Forests ; general ; Harvesting ; Herbivores ; Insects ; Life Sciences ; Life Sciences & Biomedicine ; Managed and unmanaged forest ; Outbreaks ; Pest outbreaks ; Picea mariana ; Properties (attributes) ; Research Paper ; Science & Technology ; Timber ; Tree Biology ; Trees ; Wall thickness ; Wood ; Wood anatomy ; Wood density ; Wood products ; Wood properties ; Wood Science & Technology
    ISSN: 1286-4560
    E-ISSN: 1297-966X
    Source: Web of Science - Science Citation Index Expanded - 2019〈img src="http://exlibris-pub.s3.amazonaws.com/fromwos-v2.jpg" /〉
    Source: Alma/SFX Local Collection
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  • 9
    Language: English
    In: Annals of botany, 2013-12-01, Vol.112 (9), p.1911-1920
    Description: • Background and Aims Ongoing global warming has been implicated in shifting phenological patterns such as the timing and duration of the growing season across a wide variety of ecosystems. Linear models are routiriely used to extrapolate these observed shifts in phenology into the future and to estimate changes in associated ecosystem properties such as net primary productivity. Yet, in nature, linear relationships may be special cases. Biological processes frequently follow more complex, non-linear patterns according to limiting factors that generate shifts and discontinuities, or contain thresholds beyond which responses change abruptly. This study investigates to what extent cambium phenology is associated with xylem growth and differentiation across conifer species of the northern hemisphere. • Methods Xylem cell production is compared with the periods of cambial activity and cell differentiation assessed on a weekly time scale on histological sections of cambium and wood tissue collected from the stems of nine species in Canada and Europe over 1-9 years per site from 1998 to 2011. • Key Results The dynamics of xylogenesis were surprisingly homogeneous among conifer species, although dispersions from the average were obviously observed. Within the range analysed, the relationships between the phenological timings were linear, with several slopes showing values close to or not statistically different from 1. The relationships between the phenological timings and cell production were distinctly non-linear, and involved an exponential pattern • Conclusions The trees adjust their phenological timings according to linear patterns. Thus, shifts of one phenological phase are associated with synchronous and comparable shifts of the successive phases. However, small increases in the duration of xylogenesis could correspond to a substantial increase in cell production. The findings suggest that the length of the growing season and the resulting amount of growth could respond differently to changes in environmental conditions.
    Subject(s): Cambium ; Cambium - growth & development ; Canada ; Cell Differentiation ; Cell growth ; cell production ; Cell walls ; Cellular differentiation ; Climate Change ; Coniferophyta - growth & development ; Conifers ; Europe ; growth ; Life Sciences ; meristem ; Original ; Phenology ; productivity ; secondary wall formation ; Species ; Tracheids ; Xylem ; Xylem - cytology ; Xylem - growth & development ; xylogenesis
    ISSN: 0305-7364
    E-ISSN: 1095-8290
    Source: JSTOR Life Sciences
    Source: JSTOR Ecology & Botany II
    Source: Academic Search Ultimate
    Source: PubMed Central
    Source: Alma/SFX Local Collection
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  • 10
    Language: English
    In: Forests, 2019-10-01, Vol.10 (10), p.913
    Description: Branch diameter is an important aspect of wood quality, as lumber grades can be determined based on the maximum diameter of branches. Crown and branch development can be influenced by the environment surrounding the trees, and silvicultural interventions, which reduce stand density and increase the growth of residual trees, could therefore alter branch properties. We evaluated maximum branch diameter within the crown of residual black spruce (Picea mariana (Mill.) B.S.P.) subjected to five types of silvicultural intervention-three partial-cutting and two clearcutting treatments-as well as trees within unmanaged control stands. We sampled a total of 41 stands and 223 trees. We collected 15 whorls from the live crown of each tree and measured the diameters of the largest branches. For all treatments, we observed a curvilinear relationship between maximum branch diameter and distance from the stem apex, and the largest branches were located in the lower third of the live crown. DBH before treatment and treatment were the variables that best explained maximum branch diameter in the lowest portion of the crown. A generalized additive model showed that maximum branch diameter in black spruce following silvicultural treatment will not differ significantly from trees of unmanaged control stands. Therefore, the studied partial cutting and clearcutting treatments do not have adverse effects on maximum branch diameter when compared to unmanaged control stands. However, DBH prior to treatment must be considered before any treatment is applied in forest management operations if maximum branch diameter is an important wood quality factor at the time of the final harvest of the stands.
    Subject(s): clearcutting ; Forestry ; Life Sciences & Biomedicine ; live crown ; maximum branch diameter ; partial cutting ; picea mariana (mill.) b.s.p ; Science & Technology ; silvicultural treatments
    ISSN: 1999-4907
    E-ISSN: 1999-4907
    Source: Web of Science - Science Citation Index Expanded - 2019〈img src="http://exlibris-pub.s3.amazonaws.com/fromwos-v2.jpg" /〉
    Source: DOAJ Directory of Open Access Journals - Not for CDI Discovery
    Source: ProQuest Central
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