共查询到20条相似文献,搜索用时 46 毫秒
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亲本效应(parental effect)指亲代的表现型及其所经历的环境因素而非基因型对子代表现型差异和适应性的影响,对子代适合度的维持与提高具有重要生态学意义。为探究亲本效应对鱼类胚胎发育可塑性的影响,本研究选取卵生鱼类斑马鱼(Danio rerio)为实验对象,采用2×2双因素设计,测定了不同亲本繁殖温度(22、28℃)和不同胚胎孵化温度(22、28℃)及其交互作用对斑马鱼孵化表现(孵化率、胚胎死亡率、初孵仔鱼畸形率、孵化历时、初始孵化时间、结束孵化时间)的影响。结果表明:亲本繁殖和胚胎孵化温度交互作用对斑马鱼胚胎死亡率、初始孵化时间、结束孵化时间、孵化历时等均有显著影响(P<0.05),亲本繁殖与胚胎孵化温度相一致时胚胎的死亡率更低、孵化时间更短;斑马鱼孵化表现受亲本效应(代际发育可塑性)和子代发育环境(代内发育可塑性)的双重影响,亲本效应对早期生活史阶段鱼类表型特征的塑造有重要作用。 相似文献
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永宁河是长江上游右岸的一级支流,其干、支流上共建有20余座小型水坝。为探究梯级水电站对鱼类多样性的影响,在永宁河流域设置共42个采样点,覆盖干支流及各个水坝,分别于2018年7月、10月和2019年1月、4月进行了四次鱼类资源调查。调查期间通过刺网、地笼、电捕等方法共采集到鱼类69种7332尾,隶属于4目13科54属,其中有长江上游特有鱼类13种,列入《中国脊椎动物红色名录》濒危和易危鱼类3种,国家二级重点保护鱼类岩原鲤(Procypris rabaudi)1种。Pinkas相对重要性指数(IRI)值较大主要为宽鳍鱲(Zacco platypus)、鲫(Carassius auratus)乐山小鳔鮈(Microphysogobio kiatingensis)等小型鱼类,29种鱼类的IRI值小于10;平均全长<10cm的鱼类有24种3620尾,平均体重<50g的鱼类有47种6493尾,鱼类规格较小,小型化严重。永宁河干流下游种类最多,多样性最高,干流中游鱼类数量最多。受自然环境以及水坝等的影响,永宁河的鱼类分布具有明显的空间差异。水坝类型对鱼类多样性有显著影响;而季节对鱼类多样性影响不显著。无水坝阻隔河段鱼类多样性著高于低头坝和高头坝阻隔河段;夏季的短距离洄游鱼类种数显著高于冬季和春季,但由于数量较少对鱼类多样性的季节性变化影响不明显。各种结果表明水坝阻隔对永宁河鱼类多样性和时空分布存在明显影响,为保护受小型水电站影响河流的鱼类多样性,有必要修复重要鱼类栖息地,适当拆除部分小型水坝,并科学开展增殖放流。 相似文献
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目的:考察X射线对斑马鱼早期胚胎发育的影响,探讨其影响机制.方法:用X射线照射不同发育时段的斑马鱼胚胎,统计死亡率和畸形率;应用单细胞凝胶电泳(SCGE)技术检测X射线对胚胎DNA损伤的影响;采用DCFH-DA测定胚胎活性氧;总抗氧化能力(T-AOC)测定;结果:X射线照射对斑马鱼胚胎发育有明显的影响,能够导致胚胎发育畸形如围心腔水肿、脊柱扭曲、尾部弯曲等多种畸形甚至死亡;检测X射线对斑马鱼胚胎DNA损伤时,发现X射线照射对胚胎中的DNA能够产生明显的损伤,且DNA损伤程度随胚胎发育的进行而减弱;胚胎经X射线照射后活性氧的产生增加;胚胎总抗氧化能力随着胚胎发育的进行而逐渐增强;结论:X射线照射明显影响斑马鱼胚胎发育,并造成胚胎细胞DNA损伤,发育早期胚胎敏感性高;发育后期胚胎对X射线敏感性降低,可能与胚胎细胞抗氧化能力增强有关. 相似文献
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低pH对鱼类胚胎发育、鱼苗生长及鳃组织损伤影响的研究 总被引:15,自引:1,他引:14
本文研究了低pH水平对鱼类的胚胎,鱼苗和鱼种的影响以及鱼鳃的组织学观察。在硬水环境,pH≤4.5时,对泥鳅胚胎发育有严重影响。胚胎在低pH水平下,发育进程明显地迟缓。pH≤5.5时,泥鳅幼苗的生长受到抑制;在软水环境,pH≤4.5时,影响草鱼苗和幼鱼的存活率。低pH水平加上铝则对鱼类呈现出协同毒性。低pH使鱼鳃直接遭受严重的损害:出现大量的粘液、渗血、鳃上皮肿胀和脱落,组织增生和融合。 相似文献
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为了解翘嘴鳜miR-222的时空表达规律, 研究利用实时荧光定量PCR的方法检测miR-222在翘嘴鳜不同组织、胚胎发育及胚后发育中的相对表达丰度。研究结果显示, miR-222在肌肉相关的组织中表达较高, 特别是在成年翘嘴鳜的白肌中表达最高; 胚胎发育阶段结果显示, miR-222在胚胎发育的2细胞期就有表达, 而表达量在心动期达到最高。不同组织及不同发育阶段的差异性表达结果表明, miR-222很可能参与调控鳜鱼肌肉的生长发育。为研究合成代谢过程中miR-222在肌肉生长调控中的表达规律, 通过对翘嘴鳜幼鱼在饥饿一周后饱食一餐的实验处理下, 利用实时荧光定量的方法测定miR-222在骨骼肌中的相对表达变化。结果显示, miR-222的表达量在恢复喂食后的1h显著上升(P0.05), 表明miR-222很可能是调节鱼类骨骼肌生长过程中, 参与快速应答信号系统的一类miRNA。研究为miR-222在鱼类发育中的调控作用提供一些理论依据。
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Time dependency of molecular rate estimates and systematic overestimation of recent divergence times 总被引:20,自引:0,他引:20
Studies of molecular evolutionary rates have yielded a wide range of rate estimates for various genes and taxa. Recent studies based on population-level and pedigree data have produced remarkably high estimates of mutation rate, which strongly contrast with substitution rates inferred in phylogenetic (species-level) studies. Using Bayesian analysis with a relaxed-clock model, we estimated rates for three groups of mitochondrial data: avian protein-coding genes, primate protein-coding genes, and primate d-loop sequences. In all three cases, we found a measurable transition between the high, short-term (< 1-2 Myr) mutation rate and the low, long-term substitution rate. The relationship between the age of the calibration and the rate of change can be described by a vertically translated exponential decay curve, which may be used for correcting molecular date estimates. The phylogenetic substitution rates in mitochondria are approximately 0.5% per million years for avian protein-coding sequences and 1.5% per million years for primate protein-coding and d-loop sequences. Further analyses showed that purifying selection offers the most convincing explanation for the observed relationship between the estimated rate and the depth of the calibration. We rule out the possibility that it is a spurious result arising from sequence errors, and find it unlikely that the apparent decline in rates over time is caused by mutational saturation. Using a rate curve estimated from the d-loop data, several dates for last common ancestors were calculated: modern humans and Neandertals (354 ka; 222-705 ka), Neandertals (108 ka; 70-156 ka), and modern humans (76 ka; 47-110 ka). If the rate curve for a particular taxonomic group can be accurately estimated, it can be a useful tool for correcting divergence date estimates by taking the rate decay into account. Our results show that it is invalid to extrapolate molecular rates of change across different evolutionary timescales, which has important consequences for studies of populations, domestication, conservation genetics, and human evolution. 相似文献
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Predation rate and numerical response are basic to any investigation of predator–prey relationships and key components in the selection of predators for biological control. The density-dependent predation rate and numerical response of Aphidoletes aphidimyza (Rondani) (Diptera: Cecidomyiidae) to varying densities (5, 10, 20, 40, 60 and 80) of third-instar Aphis craccivora (Koch) (Hemiptera: Aphididae), were studied in laboratory conditions [23±1°C, 70 ± 5% relative humidity (RH), and a photoperiod of 16:8 h L:D. Predation rate data were analysed using the age-stage, two-sex consumption rate software. Net consumption rate (C0) increased by increasing prey density. The lowest and highest net consumption rates were 20.75 and 190.8 prey nymphs at densities of 5 and 80 A. craccivora. The transformation rate from prey population to predator offspring (Qp) increased by increasing prey density. The reproductive numerical response, in terms of eggs laid, increased curvilinearly with increasing prey density. Females laid 121.375 ± 4.301 eggs when exposed to the highest prey density (80) and 52.5 ± 1.544 eggs at lowest prey density (5). It can be concluded that different densities of A. craccivora influenced the reproductive performance of A. aphidimyza in terms of predation rate and numerical response. 相似文献
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《Animal : an international journal of animal bioscience》2023,17(3):100715
The reproductive performance of ewes and the survivability of lambs to weaning have a critical economic impact on sheep farming worldwide. Further, knowledge of major mortality causes allows an opportunity for improved flock management to evade financial losses. The maximum likelihood estimates for generalised linear mixed models and chi-square test methods were used to examine 971 mating records, 839 and 763 lambs born and weaned (singles or twins) from the Naivasha Sheep and Goats station in Kenya for the years 2011 to 2020 consisting of Dorper, Red Maasai (RedM), and Merino breeds. The RedM (P < 0.05) outperformed Dorper and Merino in weaning rate, whereas reproductive performance between the three breeds was not significantly different (P > 0.05) in litter size and multiple lambings per ewe lambing. On the one hand, Dorper significantly (P < 0.05) outperformed the other two breeds only in weaning weight per lamb born. In addition, among all the major causes of death, pneumonia appeared to be the one to which Dorper breeds were most susceptible (chi-square test, P < 0.05). According to the findings of this study, neither the Dorper nor the Merino sheep breeds were reproductively superior to the RedM in an extensive semi-arid production environment. In addition, Dorper's susceptibility to the leading causes of mortality, particularly pneumonia and sheep pox, were relatively high compared to other breeds and could be a precursor to massive economic losses for Dorper sheep producers. In contrast to the indigenous RedM breed, imported sheep breeds appeared to be more susceptible to major mortality-related under an extensive production system. Therefore, regardless of weaning weight, RedM breed production appears to be a more viable investment for small-scale farmers, particularly in semi-arid regions. 相似文献
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通过在人工气候箱内设定不同光周期和温度梯度单虫饲养观察个体发育史,研究了光周期和温度对虎斑蝶Danaus genutia幼期存活的影响,研究结果可为该高观赏价值蝶种的规模化养殖提供依据。结果表明,在长光照(L∶D=15∶9)条件下,17.5、20.0、22.5、25.0、27.5、30.0℃时虎斑蝶卵的孵化率分别为63.72%、71.67%、65.75%、75.00%、67.12%、59.56%,幼虫的存活率分别为85.67%、85.96%、91.19%、89.20%、80.86%、68.78%,蛹的存活率分别为82.76%、100.00%、96.00%、97.06%、100.00%、100.00%;在短光照(L∶D=9∶15)条件下,17.5、20.0、25.0、30.0℃时虎斑蝶卵的孵化率分别为86.36%、67.06%、75.00%、77.50%,幼虫的存活率分别为85.05%、84.59%、85.74%、80.78%,蛹的存活率分别为93.30%、94.12%、100.00%、100.00%。结果表明,17.5℃和30.0℃均不利于虎斑蝶幼期的存活,20.0~27.5℃是其幼期生长发育适宜的温度范围。长光照利于幼虫的存活,短光照利于卵的孵化和蛹的羽化;在17.5~30.0℃内,较高的温度利于蛹的羽化,而较低的温度利于卵的孵化和幼虫的存活;温度对虎斑蝶卵的孵化、幼虫的存活及蛹的羽化影响大于光周期;在养殖生产上,建议将幼期养殖温度控制在20.0~27.5℃,幼虫期饲养在长光照下为宜,卵和蛹期置于短光照下为宜。 相似文献
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Neutral red is a weakly cationic dye that is soluble in water, has a low toxicity for almost all classes of organisms, and has been used as a histological and vital stain since the early twentieth century. Estimating the volume of water cleared of indicator material by suspension feeding bivalves (clearance or filtration rate) was one of the earliest applications of neutral red; however, less than thirty studies have applied this methodology since it was first described in 1954. The feeding/clearance rate is used as a sensitive indicator of physiological stress and is therefore an early-warning tool that is suitable for monitoring the ecological status of water bodies. The aim of our study was to optimise a clearance index based on neutral red solution by addressing the effect of i) the acidifying pH; ii) the holding temperature before spectrophotometric reading; and the time iii) before and iv) after the acidification of solutions of neutral red used to carry out clearance assays. Furthermore, as a case study we fine-tuned the clearance assay for the edible estuarine bivalve, Cerastoderma edule. The results showed that there were no statistical differences as regards the absorbance of neutral red solutions holding at 4 or 20 °C or a solution acidified between the ranges of pH 4–5. However, the absorbance significantly decreased as the pH increased to pH 6. The time before acidification had no significant effect on absorbance. Once the neutral red solution is acidified, the absorbance decreases over time, signifying that the absorbance should be read in the first 24 h. The concentration of neutral red used in the experiences should be sufficient to allow final concentrations of over 0.5 mg/L after the clearance period, since we observed that the sensitivity of this protocol decreased at low concentrations. In the case of C. edule, the optimum clearance conditions per individual were found to be 100 ml of 4 mg/L of neutral red dye during a 30 min period in dark conditions. A bioassay using a clearance index of C. edule based on this simple colorimetric technique would appear to be a potential tool for implementation in environmental monitoring programmes for water quality assessment in accordance with European directives. We trust that the new harmonised protocol will become a widely used and cost-effective means to monitor the clearance index as an indicator of physiological stress for bivalves. 相似文献
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On the interpretation of some planktonology equations 总被引:1,自引:0,他引:1
D. A. Voronov 《Oecologia》1991,88(2):303-304
Summary The concept of the mean value of a function is used to interpret some population-dynamics equations. The well-known formula for the per capita growth rate r gives a precise mean value for any (not only exponentially growing) populations. This result is used to derive the birth and death rate equations of Paloheimo (1974) with minimal initial limitations.Abbreviations
t
time
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N
number of animals
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E
number of eggs
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r
specific (i.e. per capita) population growth rate
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b
specific birth rate
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d
specific death rate
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D
duration of embryonic development 相似文献
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Nra P. Znkai 《International Review of Hydrobiology》1983,68(2):227-237
Filtering rates of three species of Daphnia were studied in situ by the 14C technique during the summer in a lake with a water temperature of 20-25°C (Lake Balaton, Hungary). The renewal time of gut contents proved to be 3-5 min in each of the three species whether fed on natural or artificial food. From May to September, filtering rates of D. cucullata, D. hyalina and D. galeata averaged 7.8, 10.3 and 9.2 ml ind.−1 day−1, respectively. Identically long individuals of all three species had almost the same filtering rates in spring, whereas in summer animals of identical weights had similar filtering rates regardless of species because of the length variability of the helmets. The grazing rate of adult filter-feeding crustaceans is suggested to be approximately 7 % per day. 相似文献
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StudiesonPaternofProducingTransgenicFishI.SeveralElementsRelatedtotheEstablishmentofTransgenicFishLIUChunqiao,ZHANGYongzhon... 相似文献
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利用闪光技术,测得若干高等植物叶片的光合单位为 1450~2050 Chl/CO_2。在含O_2 2%及CO_2浓度和光通量密度都饱和的条件下,测得叶片的连续光合速率为25~70μmol CO_2 m~(-2) s~(-1)。从上述数据及叶片叶绿素含量计算,得叶片光合单位的周转率已达80~160次/s。这样的周转速率与Emerson当初用改变闪光间暗间隔而测到的光合单位周转时间相似(即<10 ms/次,或>100次/s),从而证实了光合单位的周转与光合速率直接有关。这样的速率可称之为叶片光合的理论速率。 相似文献