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Sandra L. Almeyda Zambrano Eben N. Broadbent Sam Shanee Noga Shanee Anneke Deluycker Michael Steinberg Scott A. Ford Alma Hernndez Jaramillo Robin Fernandez‐Hilario Carolina Lagos Castillo Angelica M. Almeyda Zambrano 《American journal of primatology》2019,81(8)
Habitat loss is one of the main threats to wildlife. Therefore, knowledge of habitat use and preference is essential for the design of conservation strategies and identification of priority sites for the protection of endangered species. The yellow‐tailed woolly monkey (Lagothrix flavicauda Humboldt, 1812), categorized as Critically Endangered on the IUCN Red List, is endemic to montane forests in northern Peru where its habitat is greatly threatened. We assessed how habitat use and preference in L. flavicauda are linked to forest structure and composition. The study took place near La Esperanza, in the Amazonas region, Peru. Our objective was to identify characteristics of habitat most utilized by L. flavicauda to provide information that will be useful for the selection of priority sites for conservation measures. Using presence records collected from May 2013 to February 2014 for one group of L. flavicauda, we classified the study site into three different use zones: low‐use, medium‐use, and high‐use. We assessed forest structure and composition for all use zones using 0.1 ha Gentry vegetation transects. Results show high levels of variation in plant species composition across the three use zones. Plants used as food resources had considerably greater density, dominance, and ecological importance in high‐use zones. High‐use zones presented similar structure to medium‐ and low‐use zones; thus it remains difficult to assess the influence of forest structure on habitat preference. We recommend focusing conservation efforts on areas with a similar floristic composition to the high‐use zones recorded in this study and suggest utilizing key alimentation species for reforestation efforts. 相似文献
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The Ultrastructure of a Cyanophage Attack on Anabaena variabilis 总被引:2,自引:0,他引:2
Cyanophages multiplying on the nitrogen fixing blue-green alga Anabaena variabilis Kütz. were revealed by electron microscopy. Severe ultrastructural changes have been observed in the vegetative cells, whereas the heterocysts appeared resistant to the cyanophage. A lytic cycle was observed from adsorption to lysis. 相似文献
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Hans-Börje Jansson Angelica von Hofsten Claes von Mecklenburg 《Antonie van Leeuwenhoek》1984,50(4):321-327
The obligate endoparasitic fungus Meria coniospora lives its entire vegetative life within infected nematodes. Conidia of M. coniospora infect the nematode Panagrellus redivivus mainly in the mouth region. The infection, starting with adhesion of conidia to the nematode surface, growth of trophic hyphae, production of conidiophores and conidia, was followed using light, scanning and transmission electron microscopy.This work was supported by grants from the Swedish Natural Science Research Council. 相似文献
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Abstract— Antisera against the rat olfactory marker protein were prepared by injection of the homogeneous protein into a goat and a rabbit. When the antisera were tested by immunodiffusion against olfactory tissue extracts, many but not all mammalian species cross-reacted against these antisera. Immunoprecipitin titrations with the goat antiserum generally showed higher cross-reactivity against olfactory extracts from species more closely related to the rat. Human olfactory bulb extracts and non-mammalian olfactory tissue extracts did not cross-react with the antisera by either immunodiffusion tests or immunoprecipitin titrations, however, they did cross-react when tested by a competitive binding radioimmunoassay using tritium-labelled purified rat protein and the goat antibody. The olfactory marker protein which is an example of a brain protein specific to one cell, the olfactory chemoreceptor neuron, has a very wide species distribution, being present in rat, mouse, hamster, guinea-pig, sheep, cow, rabbit, pig, dog, man, frog and garfish. Therefore it presumably plays an important and unique role related to the function of this primary chemosensory neuron. 相似文献
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Katherine Heckman Amy Welty-Bernard Angelica Vazquez-Ortega Egbert Schwartz Jon Chorover Craig Rasmussen 《Biogeochemistry》2013,112(1-3):179-195
Iron and aluminum (oxyhydr)oxides are ubiquitous in the soil environment and have the potential to strongly affect the properties of dissolved organic matter. We examined the effect of oxide surfaces on soluble nutrient dynamics and microbial community composition using an incubation of forest floor material in the presence of (1) goethite and quartz, (2) gibbsite and quartz, and (3) quartz surfaces. Forest floor material was incubated over a period of 154 days. Aqueous extracts of the incubations were harvested on days 5, 10, 20, 30, 60, 90, and 154, and concentrations of P, N, PO4 3?, NO2 ?, NO3 ?, and organic C were measured in the solutions. Microbial community composition was examined through pyrosequencing of bacterial and fungal small subunit ribosomal RNA genes on selected dates throughout the incubation. Results indicated that oxide surfaces exerted strong control on soluble nutrient dynamics and on the composition of the decomposer microbial community, while possibly having a small impact on system-level respiration. Goethite and gibbsite surfaces showed preferential adsorption of P-containing and high molar mass organic solutes, but not of N-containing compounds. On average, organic C concentrations were significantly lower in water extractable organic matter (WEOM) solutions from oxide treatments than from the control treatment (P = 0.0037). Microbial community composition varied both among treatments and with increasing time of incubation. Variation in bacterial and fungal community composition exhibited strong-to-moderate correlation with length of incubation, and several WEOM physiochemical characteristics including apparent (weight averaged) molar mass, pH and electrical conductivity. Additionally, variation in bacterial community composition among treatments was correlated with total P (r = 0.60, P < 0.0001), PO4 3? (r = 0.79, P < 0.0001), and organic C (r = 0.36, P = 0.015) concentrations; while variation in fungal communities was correlated with organic C concentrations (r = ?0.48, P = 0.0008) but not with phosphorus concentrations. The relatively small impact of oxide surfaces on system-level microbial respiration of organic matter despite their significant effects on microbial community composition and WEOM dynamics lends additional support to the theory of microbial functional redundancy. 相似文献
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Trees tolerate an extreme heatwave via sustained transpirational cooling and increased leaf thermal tolerance
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John E. Drake Mark G. Tjoelker Angelica Vårhammar Belinda E. Medlyn Peter B. Reich Andrea Leigh Sebastian Pfautsch Chris J. Blackman Rosana López Michael J. Aspinwall Kristine Y. Crous Remko A. Duursma Dushan Kumarathunge Martin G. De Kauwe Mingkai Jiang Adrienne B. Nicotra David T. Tissue Brendan Choat Owen K. Atkin Craig V. M. Barton 《Global Change Biology》2018,24(6):2390-2402
Heatwaves are likely to increase in frequency and intensity with climate change, which may impair tree function and forest C uptake. However, we have little information regarding the impact of extreme heatwaves on the physiological performance of large trees in the field. Here, we grew Eucalyptus parramattensis trees for 1 year with experimental warming (+3°C) in a field setting, until they were greater than 6 m tall. We withheld irrigation for 1 month to dry the surface soils and then implemented an extreme heatwave treatment of 4 consecutive days with air temperatures exceeding 43°C, while monitoring whole‐canopy exchange of CO2 and H2O, leaf temperatures, leaf thermal tolerance, and leaf and branch hydraulic status. The heatwave reduced midday canopy photosynthesis to near zero but transpiration persisted, maintaining canopy cooling. A standard photosynthetic model was unable to capture the observed decoupling between photosynthesis and transpiration at high temperatures, suggesting that climate models may underestimate a moderating feedback of vegetation on heatwave intensity. The heatwave also triggered a rapid increase in leaf thermal tolerance, such that leaf temperatures observed during the heatwave were maintained within the thermal limits of leaf function. All responses were equivalent for trees with a prior history of ambient and warmed (+3°C) temperatures, indicating that climate warming conferred no added tolerance of heatwaves expected in the future. This coordinated physiological response utilizing latent cooling and adjustment of thermal thresholds has implications for tree tolerance of future climate extremes as well as model predictions of future heatwave intensity at landscape and global scales. 相似文献