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81.
Although being an important conservation tool in Africa, trophy hunting is known to influence risk perception in wildlife species, thus affecting the behaviour and fitness of most targeted species. We studied the effects of trophy hunting on the flight behaviour of impala (Aepyceros melampus), greater kudu (Tragelaphus strepsiceros) and sable (Hippotragus niger) in two closed ecosystems, Cawston Ranch (hunting area) and Stanley and Livingstone Private Game Reserve (tourist area), western Zimbabwe. Using standardized field procedures, we assessed the flight behavioural responses of the three species in two seasons: non‐hunting (December–March) and hunting (April–November) between March 2013 and November 2014. We tested the effect of habitat, group size, sex, season, start distance and alert distance on flight initiation distance using linear mixed models. Habitat, group size sex and alert distance did not have any effect on flight initiation distance for the three species. The three species were more alert and displayed longer flight initiation distances in the hunting area compared with the tourist area. Flight initiation distances for the three species were higher during the hunting season for the hunting area and low during the non‐hunting season. Flight distances of the three species did not differ between the hunting area and the tourist area. We concluded that trophy hunting increased perceived risk of wild ungulates in closed hunting areas, whereas ungulates in non‐hunting areas are less responsive and somehow habituated to human presence. Management plans should include minimum approach distances by tourists as well as establishing seasonal restrictions on special zones to promote species viability. Research aimed at integrating behavioural responses with physiological aspects of target species should be promoted to ensure that managers are able to deal with the behavioural trade‐offs of trophy hunting at local and regional scale.  相似文献   
82.
Alternative mating behaviour, personality traits and morphological characters are predicted to be correlated. Bolder, larger and more colourful males are expected to preferentially court females, while shy, small and drab‐coloured individuals are predicted to sneak copulations. We used males of Endler's guppy, Poecilia wingei, to test this association over a long temporal period (hence including ontogenetic changes) and under two social environments (male‐biased and female‐biased). We found that personality traits (exploration, boldness, activity) of P. wingei males were highly repeatable across long time spans, but they were not correlated (formed no behavioural syndrome). Male age and social environment had no effect on any personality trait, despite their effects on alternative mating behaviour. Young males with higher activity levels were more likely to attempt sneaking. In older fish, there was an association between orange coloration, courtship and boldness, but this was not observed in young males. Our results suggest that alternative mating behaviour is more flexible than personality traits and is independent of them. Non‐colour‐based morphological traits (gonopodium length, body length, caudal straps length, dorsal fin length) were not correlated with any particular mating behaviour.  相似文献   
83.
Moulton  T. P.  Burford  M. A. 《Hydrobiologia》1990,(1):401-408
The biology, and hence the mass culture, of Dunaliella viridis closely follows that of Dunaliella salina, which is successfully mass cultured for the production of -carotene. Both algae can grow at extremely high salinities and light intensities. They co-exist in the coastal salt lake, Hutt Lagoon, Western Australia. In contrast to D. salina, D. viridis does not accumulate large amounts of -carotene, producing only up to 0.7% of mixed carotenoids (lutein, zeaxathin, other oxygenated carotenoids and -carotene), compared to D. salina's ca 10% dry wt of mainly -carotene. However, in laboratory experiments, D. viridisgrew much faster and to much higher cell densities than D. salina, and attained levels of mixed carotenoids similar to those of D. salina (ca 13 mg L–1 carotenoid). Preliminary experiments in outdoor ponds were much less promising. Harvesting by chemical flocculation was as effective as with D. salina, but extraction of carotenoids directly into vegetable oil proved inefficient. When incorporated into feed, caretonoids derived from D. viridis pigmented hen eggs acceptably. Extrapolating from laboratory results, and using costing derived from D. salina technology, the cost of production of mixed oxygenated carotenoids from D. viridis was similar to that for the production of -carotene from D. salina, at ca $A500 kg–1.  相似文献   
84.
目的通过对人低分化胃癌细胞系SGC-7901状态和接种细胞数目的研究,建立良好的皮下接种胃癌的动物模型。方法采用腹腔注射SGC-7901细胞,使裸鼠形成腹水;光镜及电镜观察细胞状态;将购买的SGC-7901细胞以及形成腹水后的肿瘤细胞分别以1×108、1×107和1×106个进行裸鼠皮下接种,每组接种5只。观察其肿瘤形成时间、大小、状态及病理学变化。结果SGC-7901细胞接种裸鼠形成腹水后进行培养的肿瘤细胞增殖状态发生改变;购买的SGC-7901细胞以1×108及1×107接种裸鼠,在第21天肿瘤组织中央均出现出血和坏死;1×106的裸鼠第21天未见肉眼可见的肿瘤形成。腹水培养的肿瘤细胞,接种1×108的裸鼠在第21天肿瘤组织中央可见大面积的出血和坏死;接种1×107及1×106的裸鼠在第21天均未见出血和坏死,接种1×107的肿瘤组织体积较大。结论SGC-7901细胞接种裸鼠形成腹水后的细胞,更容易建立SGC-7901细胞皮下接种的胃癌动物模型,其中以接种细胞数为1×107的肿瘤生长较好,更适用于胃癌的实验研究。  相似文献   
85.
86.
Animal manure application as organic fertilizer does not only sustain agricultural productivity and increase soil organic carbon (SOC) stocks, but also affects soil nitrogen cycling and nitrous oxide (N2O) emissions. However, given that the sign and magnitude of manure effects on soil N2O emissions is uncertain, the net climatic impact of manure application in arable land is unknown. Here, we performed a global meta‐analysis using field experimental data published in peer‐reviewed journals prior to December 2015. In this meta‐analysis, we quantified the responses of N2O emissions to manure application relative to synthetic N fertilizer application from individual studies and analyzed manure characteristics, experimental duration, climate, and soil properties as explanatory factors. Manure application significantly increased N2O emissions by an average 32.7% (95% confidence interval: 5.1–58.2%) compared to application of synthetic N fertilizer alone. The significant stimulation of N2O emissions occurred following cattle and poultry manure applications, subsurface manure application, and raw manure application. Furthermore, the significant stimulatory effects on N2O emissions were also observed for warm temperate climate, acid soils (pH < 6.5), and soil texture classes of sandy loam and clay loam. Average direct N2O emission factors (EFs) of 1.87% and 0.24% were estimated for upland soils and rice paddy soils receiving manure application, respectively. Although manure application increased SOC stocks, our study suggested that the benefit of increasing SOC stocks as GHG sinks could be largely offset by stimulation of soil N2O emissions and aggravated by CH4 emissions if, particularly for rice paddy soils, the stimulation of CH4 emissions by manure application was taken into account.  相似文献   
87.
Female reproductive performance can be strongly affected by male care, so that breeding time, a trait expressed only by females, can be seen as one trait determined by both male and female genotypes. Animal model analyses of a 46‐year study of red‐billed gulls (Larus novaehollandiae scopulinus) revealed that laying date was not heritable in females (h2 = 0.001 ± 0.030), but significantly so in males (h2 = 0.134 ± 0.029). Heritability of breeding time in males probably reflects genetic variability in some other trait such as courtship feeding ability. In line with predictions of evolutionary models incorporating indirect genetic effects, the strong and consistent directional selection for advanced breeding time has not resulted in detectable selection response in males. Our results demonstrate that a female trait is largely determined by genetic characteristics of its mate, and hence, any evolutionary change in red‐billed gull breeding time depends critically on genetic variation in males.  相似文献   
88.
长期施肥对双季稻区红壤性水稻土质量的影响及其评价   总被引:3,自引:0,他引:3  
为量化27年连续施用化肥及其与猪粪、稻草配施处理对双季稻区土壤质量的影响,选择土壤容重、最大持水量、孔隙度、标准化平均质量直径、pH、阳离子交换量、有效养分、土壤有机质、微生物生物量碳、土壤酶和作物生产力等项目作为评价指标,并根据不同指标所具有的功能归纳为:抗物理退化的能力、养分供应和贮藏的能力、抗生物化学退化的能力、保持作物生产力的能力4项功能,以这4项功能为基础划分土壤质量指数(SQI).结果表明:SQI等级范围为0.544(CK)~0.729(施氮磷钾肥+稻草处理).与施氮磷钾肥(NPK)处理土壤相比,长期非均衡施肥的PK、NP、NK处理土壤质量发生了退化.土壤缺磷和缺钾是限制水稻生产力的主要因素,即使每年施用30 t·hm-2猪粪或4.2 t·hm-2稻草也不能达到满足高产水稻所需要的土壤磷、钾含量水平.长期施用石灰对红壤水稻土质量的提升效果不明显.在南方红壤水稻种植区,氮、磷、钾与有机肥配施是提升土壤质量的最佳措施.  相似文献   
89.
Shelly Volsche 《Anthrozo?s》2018,31(3):367-377
The American Pet Products Association reports a decade-long increase of pet spending, estimated to reach over $69 billion in 2017. In some cases, these owners apply traditional parenting practices while nurturing their pets. Relatedly, a growing number of pet owners identify themselves as “pet parents.” This study is the first known work to investigate how identity plays a role in the growing population of pet parents. While previous research into the pet parenting phenomenon has sought to quantify the demographics, spending, and frequency of this population, less work seeks to understand what pet parenting looks like in practice. Sampling a population of childfree pet parents, the current study utilized semi-structured interviews and identified two common themes in their daily practice of the identity: 1) Despite the use of parent–child terms and strategies, childfree pet parents are acutely aware of the differences between raising children and raising pets, and 2) pet parents ascribe agency to their pet, identifying individual pet wants and needs to fulfill. This may further inform future research on human–animal relationships by establishing a human identity that connects directly to pet practices in the United States, asking us to consider the lived experiences of this growing population and their pets including spending, lifestyle, and attachment concerns.  相似文献   
90.
B. K. Dutta  I. Isaac 《Plant and Soil》1979,53(1-2):99-103
Summary Organic (e.g. chitin, green manure, cellulose) amendments to soil induced quantitative and qualitative changes in the rhizosphere microflora of antirrhinum plants infected withVerticillium dahliae Kleb. Whereas reduction in disease severity occurred with chitin and green manure amendments, an increase in disease severity was observed with the application of cellulose. The reduction of the disease severity with chitin and green manure may be correlated with the increased population of actinomycetes in the antirrhinum rhizosphere.  相似文献   
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