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Disturbances, elevation, topography and spatial proximity drive vegetation patterns along an altitudinal gradient of a top biodiversity hotspot 总被引:1,自引:0,他引:1
Pedro V. Eisenlohr Luciana F. Alves Luís Carlos Bernacci Maíra C. G. Padgurschi Roseli B. Torres Eduardo M. B. Prata Flavio Antonio M. dos Santos Marco Antônio Assis Eliana Ramos André Luís C. Rochelle Fernando R. Martins Mariana C. R. Campos Fernando Pedroni Maryland Sanchez Larissa S. Pereira Simone A. Vieira José Ataliba M. A. Gomes Jorge Y. Tamashiro Marcos A. S. Scaranello Cora J. Caron Carlos Alfredo Joly 《Biodiversity and Conservation》2013,22(12):2767-2783
The correlation between vegetation patterns (species distribution and richness) and altitudinal variation has been widely reported for tropical forests, thereby providing theoretical basis for biodiversity conservation. However, this relationship may have been oversimplified, as many other factors may influence vegetation patterns, such as disturbances, topography and geographic distance. Considering these other factors, our primary question was: is there a vegetation pattern associated with substantial altitudinal variation (10–1,093 m a.s.l.) in the Atlantic Rainforest—a top hotspot for biodiversity conservation—and, if so, what are the main factors driving this pattern? We addressed this question by sampling 11 1-ha plots, applying multivariate methods, correlations and variance partitioning. The Restinga (forest on sandbanks along the coastal plains of Brazil) and a lowland area that was selectively logged 40 years ago were floristically isolated from the other plots. The maximum species richness (>200 spp. per hectare) occurred at approximately 350 m a.s.l. (submontane forest). Gaps, multiple stemmed trees, average elevation and the standard deviation of the slope significantly affected the vegetation pattern. Spatial proximity also influenced the vegetation pattern as a structuring environmental variable or via dispersal constraints. Our results clarify, for the first time, the key variables that drive species distribution and richness across a large altitudinal range within the Atlantic Rainforest. 相似文献
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Berta Lúcia Pereira Villagra Eduardo Pereira Cabral Gomes Robyn J. Burnham Sergio Romaniuc Neto 《Biodiversity and Conservation》2013,22(11):2505-2517
Climbing plant community composition and abundance was compared between the Alto da Serra de Paranapiacaba Biological Reserve (ASPRB) and the Nascentes de Paranapiacaba Municipal Natural Park (NPMNP), two protected areas in the largest Atlantic Forest remnant, southeastern Brazil. Climbing plants ≥1 cm in diameter were sampled in 52 quadrats of 10 × 20 m (1.04 ha). From these data we calculated the Shannon–Wiener diversity index, calculated abundance and importance values for families, performed a principal coordinate analysis, and created a similarity dendrogram (TWINSPAN). The composition and abundance of species between ASPRB and NPMNP differed significantly due to the successional state of the ASPRB forest, which was affected by more recent disturbance. There we found 34 species, while in the NPMNP, species richness was 72, with only 24 species in common. The two areas formed two groups corresponding to two distinct floristic subsets. These montane forests were characterized by a predominance of species of the Asteraceae. The high species richness, floristic composition, and community composition reflect the greater degree of conservation in the area of NPMNP. The high density and community composition of climbers in the more conserved area of rainforest may be due to the low intensity of disturbance. 相似文献
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Luis Alexandre Piteira Gomes Pedro Miguel Pedreirinho Salgado Eduardo Nuno Barata António Paulo Pereira Mira 《Ecological Research》2013,28(2):335-343
The alarm pheromones often released by animals under stressful situations seem to elicit behavioral changes in conspecifics, which in the appropriate context can be viewed as anti-predatory responses. However, the releasing of alarm pheromones associated with predatory events has not been demonstrated in mammals. In the current study with wild-caught Cabrera voles, we carried out experiments in the laboratory and in the field to assess the release of alarm pheromones in scent-marks during simulated predatory events and disclose their effects on conspecifics. We first conducted an assay wherein voles where let to scent-mark a clean substrate in the absence of disturbance (control) and under the simulation of predatory events. Contrarily to the control, no fecal boli were released and the area marked with urine was significantly larger during the predatory simulation. In a subsequent assay, we assessed the voles’ preference between urine-marks released under predatory simulation and in control conditions. Voles showed a significant preference by control substrates. Finally, a third assay was carried out in the vole’s habitat wherein the individual activity was monitored by radio-tracking before and after placement of urine-marks obtained during the conditions described above. The vole’s activity was only reduced near the urine-marks released during the simulated predatory events. The results suggest that: (1) during predatory attempts, Cabrera voles release an alarm pheromone in their urine-marks; (2) the putative alarm pheromone reduces the voles’ activity in the surroundings of the marked area; (3) the putative alarm pheromone persists in the field affecting conspecifics’ activity for several days. 相似文献
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Andréa Helena Vidal André Mariano Batista Ellen Cordeiro Bento da Silva Wilton Arruda Gomes Marina Arruda Pelinca Sildivane Valcácia Silva Maria Madalena Pessoa Guerra 《Small Ruminant Research》2013,109(1):47-51
The aim of this study was to evaluate the effect of different concentrations of soybean lecithin (SL) in extenders for sperm goat cryopreservation. Sexually mature male Saanen goats (n = 4) were used, and the ejaculates were obtained using an artificial vagina method. The semen samples were pooled and diluted in a skim milk-based extender (control group; CG) or Tris extender supplemented with SL at different concentrations (G1 = 0.04%, SL G2 = 0.08% SL and G3 = 0.16%) for a final concentration of 240 × 106 spermatozoa/mL. The semen samples were packed in straws (0.25 mL), frozen using an automated system and stored in liquid nitrogen (?196 °C). After thawing (37 °C/30 s), the samples were evaluated for sperm quality parameters, including sperm motility, membrane integrity, acrosome integrity and mitochondrial activity. No significant difference was observed among the experimental and control groups for all of the parameters (P > 0.05). However, even though the control group presented a significantly lower mitochondrial membrane potential compared to fresh semen (P < 0.05), the same did not occur for the extender supplemented with soybean lecithin, that is, it did not differ from fresh sperm (P > 0.05). The extender containing soybean lecithin at different concentrations preserved the sperm quality parameters in a manner similar to the conventional skim milk-based extender. Thus, it is concluded that an extender containing soybean lecithin as the lipoprotein source can be used for freezing goat semen. 相似文献
108.
Emanuele Lombardo Cristian Sabellico Jan Hájek Veronika Staňková Tomá? Filipsky Valentina Balducci Paolo De Vito Stefano Leone Eugenia I. Bavavea Ilaria Proietti Silvestri Giuliana Righi Paolo Luly Luciano Saso Paolo Bovicelli Jens Z. Pedersen Sandra Incerpi 《PloS one》2013,8(4)
Natural polyphenol compounds are often good antioxidants, but they also cause damage to cells through more or less specific interactions with proteins. To distinguish antioxidant activity from cytotoxic effects we have tested four structurally related hydroxyflavones (baicalein, mosloflavone, negletein, and 5,6-dihydroxyflavone) at very low and physiologically relevant levels, using two different cell lines, L-6 myoblasts and THP-1 monocytes. Measurements using intracellular fluorescent probes and electron paramagnetic resonance spectroscopy in combination with cytotoxicity assays showed strong antioxidant activities for baicalein and 5,6-dihydroxyflavone at picomolar concentrations, while 10 nM partially protected monocytes against the strong oxidative stress induced by 200 µM cumene hydroperoxide. Wide range dose-dependence curves were introduced to characterize and distinguish the mechanism and targets of different flavone antioxidants, and identify cytotoxic effects which only became detectable at micromolar concentrations. Analysis of these dose-dependence curves made it possible to exclude a protein-mediated antioxidant response, as well as a mechanism based on the simple stoichiometric scavenging of radicals. The results demonstrate that these flavones do not act on the same radicals as the flavonol quercetin. Considering the normal concentrations of all the endogenous antioxidants in cells, the addition of picomolar or nanomolar levels of these flavones should not be expected to produce any detectable increase in the total cellular antioxidant capacity. The significant intracellular antioxidant activity observed with 1 pM baicalein means that it must be scavenging radicals that for some reason are not eliminated by the endogenous antioxidants. The strong antioxidant effects found suggest these flavones, as well as quercetin and similar polyphenolic antioxidants, at physiologically relevant concentrations act as redox mediators to enable endogenous antioxidants to reach and scavenge different pools of otherwise inaccessible radicals. 相似文献
109.
Filumena Maria Gomes S. V. Subramanian Ana Maria de Ulh?a Escobar Maria Helena Valente Sandra Josefina Ferraz Ellero Grisi Alexandra Brentani Günther Fink 《PloS one》2013,8(6)