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在4个温度(15、20、25、30℃)和3个食物浓度(1×104,1×105,5×105 cells ml-1)下研究了大型溞(Daphnia magna)淮河种群的动态和两性生殖,结果表明:(1)在实验初期,大型溞种群密度不断增加,达到最大值后种群密度呈现缓慢下降或趋于稳定的趋势.除15℃下最大瞬时增长率(1.36 d-1)出现在中食物浓度组外,20℃(1.51 d-1)、25℃(1.39 d-1)、30℃(0.69 d-1)下的最大瞬时增长率均出现在高食物浓度组.(2)相同温度下,食物浓度与大型溞最大种群密度间存在显著正相关(p<0.01).(3)相同食物浓度下,随温度升高,大型溞首次产幼溞时间(5~21d)和到达最大种群密度的时间(15~29d)缩短,首次抱卵时的体长(1.75~2.67 mm)减少.(4)在较低的温度和中食物浓度组下,大型溞产生了较多的休眠卵或卵鞍(15℃:(16.7±2.5) ind. 和20℃:(18.3±3.8) ind.);30℃下没有出现休眠卵或卵鞍.除15℃、中食物浓度组外,其它实验组均产生雄体.实验25d后,雄体密度与种群密度呈显著的相关性(30℃:p<0.05;15~25℃:p<0.01).(5)本研究结果暗示大型溞休眠卵的形成受温度、食物浓度和种群密度的共同影响,且较低的温度是大型溞休眠卵形成的主要诱因. 相似文献
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在20℃、25℃下,将大型溞和老年低额溞分别按7+3(B组),5+5(C组),3+7(D组)的组合进行混合培养,以及用单种培养(10+0(A组),0+10(E组))作为对照,研究了温度和种间竞争对大型溞种群动态和两性生殖的影响.实验结果表明:在混合培养时,大型溞对老年低额溞产生明显的竞争优势.20℃、25℃下,单种培养的老年低额溞最大种群密度分别为大型溞的2.31和1.97,而在混合培养下老年低额溞的种群密度明显低于大型溞,在实验25d后几乎全部死亡.25℃下两种溞的种群密度之间存在极显著的负相关性(C组:r=-0.508,n=30,P<0.01;D组:r=-0.483,n=30,P<0.01).在20℃、单种培养下,大型溞在首次产幼溞时即出现雄体,且种群密度与雄体密度呈显著的相关性(r=0.678,n=24,P<0.01).大型溞的最大雄体密度(106 ind.(200ml)~(-1))和最大雄体比例(36.8%)均出现在20℃、单种培养下.25℃下,大型溞在混合培养的B组和C组首次产幼溞时即出现雄体,且雄体在混合培养B组的比例达28.2%.大型溞在25℃、单种培养下没有产生卵鞍,在混合培养下总计产生66个卵鞍,其中空卵鞍占51.5%,而在20℃、混合培养下没有卵鞍产生.实验结果暗示:在较高的温度下,种间竞争刺激了大型溞雄体的产生和卵鞍的形成,高密度的雄体有助于大型溞孤雌生殖雌体向两性生殖雌体的转化. 相似文献
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研究了不同温度和食用藻密度对发头裸腹溞种群动态和两性生殖的影响.结果表明: 温度、食用藻密度对发头裸腹溞的种群密度、雄体密度和卵鞍数均有显著影响.高食用藻密度组的发头裸腹溞种群密度明显高于中、低食用藻密度组,其最大种群密度出现在20 ℃下的高食用藻密度组.在相同的温度下,发头裸腹溞的首次产幼溞数随食用藻密度的降低而减少,平均每个母溞首次产出的最大幼溞数出现在25 ℃下的高食用藻密度组.高食用藻密度组发头裸腹溞产生的雄体密度明显高于中、低食用藻密度组.发头裸腹溞的雄体密度与其种群密度之间存在极显著的相关性.发头裸腹溞所产的卵鞍数随食用藻密度的下降而下降,且25 ℃下发头裸腹溞所产的卵鞍数明显高于其他温度组.与温度相比,食用藻密度对发头裸腹溞的种群动态和两性生殖的影响更大. 相似文献
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研究了不同温度和食用藻密度对发头裸腹潘种群动态和两性生殖的影响.结果表明:温度、食用藻密度对发头裸腹溞的种群密度、雄体密度和卵鞍数均有显著影响.高食用藻密度组的发头裸腹潘种群密度明显高于中、低食用藻密度组,其最大种群密度出现在20℃下的高食用藻密度组.在相同的温度下,发头裸腹溞的首次产幼溞数随食用藻密度的降低而减少,平均每个母潘首次产出的最大幼潘数出现在25℃下的高食用藻密度组.高食用藻密度组发头裸腹潘产生的雄体密度明显高于中、低食用藻密度组.发头裸腹溞的雄体密度与其种群密度之间存在极显著的相关性.发头裸腹溞所产的卵鞍数随食用藻密度的下降而下降,且25℃下发头裸腹溞所产的卵鞍数明显高于其他温度组.与温度相比,食用藻密度对发头裸腹潘的种群动态和两性生殖的影响更大. 相似文献
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种群密度和培养体积对发头裸腹溞生长和繁殖的影响 总被引:1,自引:0,他引:1
研究了不同培养密度(D1=100 ind·L-1,D2=150 ind·L-1,D3 =300 ind·L-1)和培养体积(V1 =50 mL,V2=100 mL,V3 =400 mL)对发头裸腹溞生长和生殖的影响.结果表明:在相同培养密度下,发头裸腹溞首次怀卵体长、雌体第一窝幼溞数和后代总数均随着培养体积的增大而减少,而雌体所产后代的性比(雄体∶雌体)随着培养体积的增大而增大.在相同培养体积下,雌体产出后代总数随着培养密度的增加而减少.雌体最大首次怀卵体长(0.95±0.10 mm)和最大后代总数(171.3±19.8 ind)均出现在D1V1组合,最大性比(0.54±0.05)出现在D3V2组合.培养密度和培养体积及其协同作用对发头裸腹溞雌体后代总数、后代性比均具有显著影响(P<0.001). 相似文献
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本文报道了南京玄武湖微型裸腹溞和短尾秀体溞的种群变动和生产量的研究结果,并分析了影响它们的生态因子。计算了种群的瞬时出生率(b),瞬时增长率(r)和瞬时死亡率(d)。观察了微型裸腹溞怀卵量的季节变化。微型裸腹溞生长季节平均生物量为87.51μg/L(干重),生产量为8292.36μg/L(干重),P/B系数为94.76;短尾秀体溞生长季节平均生物量为9.58μg/L(干重),生产量为480.02μg/L(干重),P/B系数为50.52。 相似文献
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研究了3种微生态制剂(复合微生态制剂Ⅰ、复合微生态制剂Ⅱ和芽孢杆菌)对大型溞的急、慢性毒性影响,分析比较了3种微生态制剂的安全使用剂量以及对大型溞生殖和种群增长的影响.试验结果表明,3种微生态制剂对大型溞死亡率影响均显著(P < 0.05),从安全浓度来看,对大型溞的毒性作用依次为:复合微生态制剂Ⅱ>复合微生态制剂Ⅰ>芽孢杆菌;在安全浓度范围内,3种微生态制剂对大型溞亲代(P)的生殖和种群增长均有明显的促进作用,表现在随微生态制剂浓度的升高,P代的净生殖率(R0)和内禀增长率(rm)均显著增加(P < 0.05),其中以复合微生态制剂Ⅰ的效果最好,R0最高值为对照组的7倍,rm最高值为对照组的1.7倍;3种微生态制剂对大型溞子一代(F1)和子二代(F2)的生殖和种群增长均没有促进作用. 相似文献
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稀有种具有典型的狭域分布和生境利用专化等特点,可能携带着物种致危机制的重要信息,厘清其稀有成因将有力促进生态学理论的进一步发展。盾额隆背溞是一种罕见枝角类,国内仅记述过4个样品。除少量分类学形态描述外,其关键性生物学及生态学特征迄今尚未被揭示。本研究在滇池流域枝角类系统调查中首次采集得到盾额隆背溞活体,通过扩繁取得丰富研究材料,并围绕其种群结构、种群繁殖力、种群动态参数等关键种群生态学特征开展研究,以初步了解其种群稀有成因。2022—2023两年的研究结果显示,盾额隆背溞为微小型枝角类(体长0.30~1.15 mm),初次性成熟体长约为0.52 mm。未在种群中检出雄性个体。2022年室外种群夏卵繁殖力为(2.2±1.4) eggs·ind-1(n=334, 最大值为8 eggs·ind-1),2023年为(4.8±2.8) eggs·ind-1 (n=94, 最大值为13 eggs·ind-1)。产冬卵时,卵鞍含卵2个。在生命表试验中,以小球藻培养的种群子一代(F1)、子二代(F2)最大繁殖龄期数分别为8和7个,总生殖率分别为30.3和9.4 eggs·ind-1,最长个体寿命分别为21和16 d,种群内禀增长率分别为0.37和0.36;以泥糜培养液培养的种群F1、F2最大繁殖龄期数均为8个,其总生殖率分别为40.3和36.1 eggs·ind-1,最长个体寿命分别为28 和27 d,内禀增长率分别为0.31和0.30。在合适环境下盾额隆背溞种群增长迅速,其瞬时增长率为每天0.39,在第10天种群数量已达起始的50倍,相对密度达510 ind·L-1,并进入平台期。在自然环境中其种群丰度极低,2022年在水体干枯期种群消失;在2023年的连续观察中,其种群在丰水期突然从观察区域完全消失。分析表明,盾额隆背溞具有相对较长寿命、较高繁殖力及较强的种群增长潜力,与众多常见种相比没有呈现明显的劣势,其在自然界中种群稀少可能并不是由其个体生物学及种群生态学基本特征受限所致,而是对环境选择压力应对具脆弱性所致。 相似文献
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Theory predicts that genetic diversity and genetic differentiation may strongly vary among populations of the same species depending on population turnover and local population sizes. Yet, despite the importance of these predictions for evolutionary and conservation issues, empirical studies comparing high‐turnover and low‐turnover populations of the same species are scarce. In this study, we used Daphnia magna, a freshwater crustacean, as a model organism for such a comparison. In the southern/central part of its range, D. magna inhabits medium‐sized, stable ponds, whereas in the north, it occurs in small rock pools with strong population turnover. We found that these northern populations have a significantly lower genetic diversity and higher genetic differentiation compared to the southern/central populations. Total genetic diversity across populations was only about half and average within‐population diversity only about a third of that in southern/central populations. Moreover, an average southern population contains more genetic diversity than the whole metapopulation system in the north. We based our analyses both on silent sites and microsatellites. The similarity of our results despite the contrasting mutation rates of these markers suggests that the differences are caused by contemporary rather than by historical processes. Our findings show that variation in population turnover and population size may have a major impact on the genetic diversity and differentiation of populations, and hence may lead to differences in evolutionary processes like local adaptation, hybrid vigour and breeding system evolution in different parts of a species range. 相似文献
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环境因子对萼花臂尾轮虫休眠卵萌发率的影响 总被引:7,自引:2,他引:7
萼花臂尾轮虫(Brachiounus calyciflorus Pallas)休眠卵在不同萌发条件下累积萌发率的结果显示,保存在休眠卵形成的原液中,温度为20℃~30℃时萌发率均较高,30℃时用过滤湖水萌发时的萌发率最高(65%),保存在无机培养中的休虎卵,用曝气自来水萌发时最主,用湖水次之,无机液萌发效果较差;20℃和25℃时三种萌发液中的萌发率接近,母体投喂小球藻形成的休眠卵的累积萌发率高于投 相似文献
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在不利的环境条件下,枝角类中有一部分种类可以形成卵鞍(ephippium),内含休眠卵。本文应用扫描电镜和透射电镜对隆线溞的卵鞍进行了超微结构的研究。研究表明:卵鞍外面大部分略呈浅的蜂窝状,内面则排布着多数卵石状小突起。卵鞍分为内外两层,两层的超微结构截然不同;各层又可分为三小层。 相似文献
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Mikael T. Ekvall Yongcui Sha Tobias Palmér Giuseppe Bianco Johan Bäckman Kalle Åström Lars-Anders Hansson 《Freshwater Biology》2020,65(9):1509-1517
- Organisms in the wild are faced with multiple threats and a common response is a change in behaviour. To disentangle responses to several threats, we exposed two differently sized species of the freshwater invertebrate Daphnia to solar ultraviolet radiation (UVR) and predation from either moving pelagic or benthic ambush predators.
- Using an advanced nanotechnology-based method, we tracked the three-dimensional movements of those mm-sized animals at the individual level. Each behavioural trial was performed both under conditions resembling night (no UVR) and day (UVR) and we examined patterns of the depth distribution and swimming speed by Daphnia across three treatments: no predator (control); bottom-dwelling damselfly (Calopteryx sp.); and fish (stickleback, Pungitius pungitius) predators. We also quantified the actual predation rate by the two predators on the two Daphnia species, Daphnia manga and Daphnia pulex.
- We show that individual Daphnia are able to identify predators with different feeding habitats, rank multiple and simultaneously occurring risks and respond in accordance with the actual threat; complex responses that are generally associated with larger animals.
- In a broader context, our results highlight and quantify how a cocktail of everyday threats is perceived and handled by invertebrates, which advances our understanding of species distribution in space and time, and thereby of population dynamics and ecosystem function in natural ecosystems.
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Observations were done on the effect of inorganic substances on the gut evacuation process in Daphnia magna. Procedures which accelerate this process are described. 相似文献
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于2012年9月通过浮游动物添加实验,研究了大型溞(Daphnia magna)和隆腺溞(Daphnia carinata)对上海滴水湖浮游植物群落结构的影响.结果表明,实验组氨氮和可溶性活性磷浓度与空白组相比显著增加,大型溞组浮游植物密度较空白组降低了70.3%,隆腺溞组浮游植物密度较空白组降低了80.0%,叶绿素a浓度分别下降了80.4%和75.2%,叶绿素a与氨氮、可溶性活性磷呈显著相关性.浮游植物的群落结构较空白组也发生较大变化,硅藻、蓝藻和绿藻密度比例明显降低,隐藻、裸藻和甲藻在实验结束时没有检出,说明大型溞和隆线溞能有效控制水体中浮游植物密度,并能够对浮游植物群落结构产生影响.同时,附着藻类密度较空白组也有明显减少,说明大型溞和隆线溞对附着藻类也有一定的牧食作用. 相似文献
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《Electromagnetic biology and medicine》2013,32(1):30-39
This study investigates the effects of lifelong exposure to reversed geomagnetic and zero geomagnetic fields (the latter means absence of geomagnetic field) on the life history of Daphnia carinata King from Australia and Daphnia magna Straus from Europe. Considerable deviation in the geomagnetic field from the usual strength, leads to a decrease in daphnia size and life span. Reduced brood sizes and increased body length of neonates are observed in D. magna exposed to unusual magnetic background. The most apparent effects are induced by zero geomagnetic field in both species of Daphnia. A delay in the first reproduction in zero geomagnetic field is observed only in D. magna. No adaptive maternal effects to reversed geomagnetic field are found in a line of D. magna maintained in these magnetic conditions for eight generations. Integrally, the responses of D. magna to unusual geomagnetic conditions are more extensive than that in D. carinata. We suggest that the mechanism of the effects of geomagnetic field reversal on Daphnia may be related to differences in the pattern of distribution of the particles that have a magnetic moment, or to moving charged organic molecules owing to a change in combined outcome and orientation of the geomagnetic field and Earth's gravitational field. The possibility of modulation of self-oscillating processes with changes in geomagnetic field is also discussed. 相似文献
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Lynn Govaert Luc De Meester Sarah Rousseaux Steven A. J. Declerck Jelena H. Pantel 《Oikos》2021,130(10):1773-1787
There are currently few predictions about when evolutionary processes are likely to play an important role in structuring community features. Determining predictors that indicate when evolution is expected to impact ecological processes in natural landscapes can help researchers identify eco-evolutionary ‘hotspots', where eco-evolutionary interactions are more likely to occur. Using data collected from a survey in freshwater cladoceran communities, landscape population genetic data and phenotypic trait data measured in a common garden, we applied a Bayesian linear model to assess whether the impact of local trait evolution in the keystone species Daphnia magna on cladoceran community trait values could be predicted by population genetic properties (within-population genetic diversity, genetic distance among populations), ecological properties (Simpson's diversity, phenotypic divergence) or environmental divergence. We found that the impact of local trait evolution varied among communities. Moreover, community diversity and phenotypic divergence were found to be better predictors of the contribution of evolution to community trait values than environmental features or genetic properties of the evolving species. Our results thus indicate the importance of ecological context for the impact of evolution on community features. Our study also demonstrates one way to detect signatures of eco-evolutionary interactions in communities inhabiting heterogeneous landscapes using survey data of contemporary ecological and evolutionary structure. 相似文献