排序方式: 共有197条查询结果,搜索用时 0 毫秒
81.
82.
In the Pantanal wetlands of Central Brazil, the endangered hyacinth macaw (Anodorhynchus hyacinthinus), the largest psitacid in the world, makes its nest almost exclusively in natural hollows found in the manduvi tree (Sterculia apetala). The recruitment of manduvis greatly depends on the seed dispersal services provided by the toco toucan (Ramphastos toco), responsible for 83.3% of the seed dispersal. The toco toucan, however, is responsible for about 53% of the preyed eggs, resulting in a case of conflicting ecological pressures in which the reproduction of the hyacinth macaw is indirectly dependent on the seed dispersal services of its nest predator. The case illustrates the intricacies of biotic interactions in species-rich environments where species may be tied by indirect, subtle ecological links which conservationists should be aware of. 相似文献
83.
Elialdo Alves DE SOUZA Natlia Rodrigues FERREIRA-ELOY Camila da Silva GRASSMANN Ciro Antonio ROSOLEM Philip J. WHITE 《土壤圈》2019,29(4):534-539
<正>Dear Editor,Phosphorus(P) deficiency is the most limiting factor in tropical agriculture since most soils in this region are predominantly acids with high-energy P-binding compounds. Therefore, up to 90% of the P applied becomes fixed in soils, which raises environmental concerns and production costs(Syers et al., 2008). Thus,developing strategies to improve P use efficiency(PUE) 相似文献
84.
85.
Mauro Galetti Henrique C. Giacomini Christine S.S. Bernardo Ricardo S. Bovendorp Paulo Rubim Camila I. Donatti Rodrigo A. Begotti Rodrigo de A. Nobre Carlos A. Peres 《Biological conservation》2009,142(6):1229-1241
Large mammal faunas in tropical forest landscapes are widely affected by habitat fragmentation and hunting, yet the environmental determinants of their patterns of abundance remain poorly understood at large spatial scales. We analysed population abundance and biomass of 31 species of medium to large-bodied mammal species at 38 Atlantic forest sites (including three islands, 26 forest fragments and six continuous forest sites) as related to forest type, level of hunting pressure and forest fragment size using ANCOVAs. We also derived a novel measure of mammal conservation importance for each site based on a “Mammalian Conservation Priority index” (MPi) which incorporates information on species richness, population abundance, body size distribution, conservation status, and forest patch area. Mammal abundance was affected by hunting pressure, whereas mammalian biomass of which was largely driven by ungulates, was significantly influenced by both forest type and hunting pressure. The MPi index, when separated into its two main components (i.e. site forest area and species-based conservation index Ci), ordered sites along a gradient of management priorities that balances species-focused and habitat-focused conservation actions. Areas with the highest conservation priority were located in semi-deciduous forest fragments, followed by lowland forests. Many of these fragments, which are often embedded within large private landholdings including biofuel and citrus or coffee crops, cattle ranches and pulpwood plantations, could be used not only to comply with environmental legislation, but also enhance the prospects for biodiversity conservation, and reduce edge effects and hunting. 相似文献
86.
Etelvina M. C. G. Nunes Maria M. G. Pereira Amilton P. R. Costa Mara N. B. A. Araripe Rodrigo M. Calvet Carina M. Pereyra Maria L. X. Azevedo Raizza E. E. Pinheiro Verbena C. Alves Airton M. Conde Jnior Lidiane S. N. Ramos Joao B. Lopes Camila G. Marinho Mara C. S. Muratori 《International Aquatic Research》2019,11(1):73-83
The detection of mycotoxins in feeds and their ingredients in aquaculture gained prominence due to losses caused in production and animal health, mainly the occurrence of aflatoxin (AFB1). The aim of this study was to evaluate the effects of AFB1 on the performance of tambaqui fingerlings (Colossoma macropomum). Four hundred tambaqui were used. Four different treatments were evaluated: treatment T1, considered as the control treatment (CT) with 3.84 μg kg−1; treatment T2, treatment T3 and treatment T4 with 500, 1000 and 2000 μg kg−1 of AFB1, respectively. The AFB1 of the samples (muscle, liver and kidney) was detected by high-pressure liquid chromatography. Four fingerlings from each treatment for histological analysis were examined. Moreover, the performance parameters (weight gain, feed conversion and feed intake) were studied. The levels of toxins used in T2, T3 and T4 represent a reduction in the growth of 14%, 35% and 45%, respectively. The T3 and T4 showed the lowest weight gain (78%) and the worst feed conversion. Aflatoxin B1 in muscle (3.28 μg kg−1) and kidneys (8.8 μg kg−1) in the T3, as well as liver (4.4 μg kg−1) and kidney (4.08 μg kg−1) in T4, was detected. Histopathological changes in liver and kidney tissues of fingerlings were more pronounced in T3 and T4. Fingerlings that consume feed contaminated with AFB1 in concentrations higher than 500 μg kg−1 present decreases in growth, reduction in weight gain and feed intake with increased feed conversion. The consumption of feed contaminated with 1000 and 2000 μg kg−1 of AFB1 caused severe deterioration in the hepatic and renal tissues. 相似文献
87.
Camila Pegoraro Liliane Marcia Mertz Luciano Carlos da Maia Cesar Valmor Rombaldi Antonio Costa de Oliveira 《Journal of Crop Science and Biotechnology》2011,14(2):85-95
Abiotic and biotic stress conditions cause extensive losses to maize production, mainly due to protein dysfunction in these
conditions. In higher plants, the occurrence of heat-shock proteins (HSPs) in response to different environmental stresses
is a universal phenomenon and has been well documented. Many studies have demonstrated that most HSPs are involved in many
regulatory pathways, act as molecular chaperones for other cell proteins, and have strong cytoprotective effects. Although
many functional roles for HSPs are known, the mechanisms for these multiple functions are not entirely understood. Here we
reviewed the correlation among HSP genes/proteins and plant tolerance, especially maize, in different environmental stresses. Due to the low availability of
information regarding the expression of HSP genes in response to different stresses in maize, we decided to mine databases in order to generate new insights related
to this topic. 相似文献
88.
Márcio de Oliveira Marques Fábio Morotti Camila Bizarro da Silva Mario Ribeiro Júnior Rubens César Pinto da Silva Pietro Sampaio Baruselli Marcelo Marcondes Seneda 《Journal of veterinary science (Suw?n-si, Korea)》2015,16(3):367-371
This study was conducted to evaluate the influence of category (heifers, primiparous or multiparous cows) on pregnancy rates in a large scale resynchronization ovulation program. Nelore heifers (n = 903), primiparous lactating cows (n = 338) and multiparous lactating cows (n = 1,223) were synchronized using a conventional protocol of estradiol/P4-based fixed-time artificial insemination (FTAI). Thirty days after ultrasonography, females who failed the first FTAI were resynchronized with the same hormonal protocol prior to a second FTAI. The pregnancy status of each cohort was evaluated by ultrasonography 30 days after each FTAI. The average conception rate after the first FTAI and resynchronization was 80.5%. Heifers had a higher conception rate (85%) than primiparous (76%) or multiparous cows (78%; p = 0.0001). The conception rate after the first FTAI was similar among heifers (57%), primiparous cows (51%) and multiparous cows (56%; p = 0.193). After the second FTAI, heifers exhibited a higher conception rate (66%) than primiparous or multiparous cows (51%; p = 0.0001). These results demonstrate the feasibility of resynchronization in large beef herds for providing consistent pregnancy rates in a short period of time. We also demonstrated that ovulation resynchronization 30 days after FTAI is particularly effective for heifers, providing a conception rate of up to 66%. 相似文献
89.